OpenCircuits - User contributions [en]

Programmable Chip EEG

2007-07-18T13:13:01Z

204.80.61.114: /* Description of How it Works */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring.

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the PIC18 which will, further process the signals, and provide an interface to a computer.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using EAGLE CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is digitised by a analog to digital converter. The a/d converter has aproxamitly 20 bits acuracy so the signal does not have to be conditioned or filtered as much.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the PIC18 useing great cows basic.
=== How You Can Help ===
#. get the tools

== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* EAGLE CAD is being used to create the first PCB surface mount is used to save space.
* Maxima a computer algebra system s used for graphing and math displays.
*SPI interface for a/d converters
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*GEDA tools may be a option for opening this design to a wider audience.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the UBW which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 20 bit ADC.

''(In 2007-02, some one claimed "We expect this project to require at least 20 bit ADC." -- why? Many people (*) do EKGs with only 10 bit converters.)''

* $12.00 The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS. It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]
* TI app note [http://focus.ti.com/docs/solution/folders/print/272.html "Biophysical Monitoring: Electrocardiogram (ECG) Front End"] has a simple circuit: 390 KOhm resistors in-line with each lead -- one end touches patient, the other end directly connected to the instrumentation amp input (or the right-leg drive amplifier output, which has no further protection). The inst. amp has 2 protection diodes on each input, directly to +power and -power. Also, 39 pF capacitor from each input to analog GND, and 200 pF between the 2 inputs. The TI publication "Information for Medical Applications" (2Q 2004) reprints that circuit, but leaves out the caps and the diodes.
* (*) [http://www.ieeta.pt/~escadas/ucecg/applications.htm Some people use 420 Hz sampling rate, 10 bits/sample.]
* [http://bsamig.uku.fi/pdf/QRSdet.pdf "High-Resolution QRS Detection Algorithm for Sparsely Sampled ECG Recordings"] by Timo Bragge et. al. 2004 recommends: "the sampling frequency of the ECG should be at least 500 Hz"
* [http://www.analog.com/library/analogDialogue/archives/29-3/low_power.html "Low-Power, Low-Voltage IC Choices for ECG System Requirements"] by Jon Firth and Paul Errico says "The multiplexed architecture, based on an old assumption that the converter is by far the most-expensive front-end component, is prevalent in today's electrophysiological measurement systems. However, with the proliferation of sigma-delta converter architectures, converter-per-channel is now a power- and cost-competitive alternative". It also gives a typical schematic for both architectures and suggests some parts.
* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]?

[[Category:Projects]]

User talk:DavidCary

2007-07-18T13:08:26Z

204.80.61.114: /* a talk through Wiki Howto */

Why don't you help finish my programmable chip eeg project and then use what you learned and the results to then create your own project. Programmers like to reuse working modulas instead of reinventing the wheel.

==a talk through Wiki Howto==
The pceeg has gone through a major revision streamlining its design and I am working on the father board a digital computing board for the project. I will be cleaning up the page.
Hi DavidCary
<br>Thank you very much you create this wiki to let us to share electronic projects.
<br>I want to merge the "[[RS232 Dev Board]]" and "[[RS232 RS485 USB Converter Board]]", so want to discuss to the author, Tkb, of "RS232 Dev Board". However, i cannot find out the talk page like i talk to you by this way. Can you point me how to do it?
<br>thanks
<br>[[User:Yan|yan]]

''If you have a question or comment specifically about the "RS232 Dev Board", please leave a comment on the [[RS232 Dev Board]] page or its "discussion" page.''
''You can click on "[[User talk:Tkb]]" to leave a note on Tkb's user talk page.''
''Since there are more people watching the "RS232 Dev Board" page than Tkb's page, you'll probably get a quicker response if you post to the "RS232 Dev Board" page than to Tkb's page.''
''--[[User:DavidCary|DavidCary]] 20:00, 29 December 2006 (PST)''

[[User:Chazegh|Chazegh]] created this "Open Circuits wiki".
I am flattered that you think I had something to do with it.
But since Chazegh seems to be too busy to spend much time here,
it's up to you and I (and whoever else we can recruit) to create content here.
--[[User:DavidCary|DavidCary]] 21:08, 29 December 2006 (PST)

5.7.2007 Joe Silva:
Hi David, great site! I've taken the liberty to remove some SPAM links from the pages. Yeah we sure do need an anti-valdalism bot. Also maybe not allow anonymous editing.

----

Aloha David,
Roger here, I'm still puzzeled as to how to create a new article. I uploaded an image file for the 723 regulator (my article subject). This went into an "Image File page" automatically, OK. I added it to the Voltage Regulators section of Components/Integrated Circuits, OK. But I couldn't figure out how to make a document like there is for LT1528 OO. I put the info I have into the discussion page for the image, but that is only a temporary solution.

How does one create a new article page that isn't a "talk" page for something else? Beside the info on the IC, I have a couple of documents that are in-depth on using the device. These should be near each other as well as near the info document above. How would I go about setting up a "723" sub-chapter of "Integrated Circuits"? I guess that's as clear as I can make the question.

I would also like to suggest a modification to the linkage. I'm reading the synopsis on the LT1528, I want to find oout more, so I click on the image, but instead of taking me to an in-depth article, it takes me to the image file page. There I have to look at the Links to find the article (which is only identified as LT1528). I'd like to be taken to the article instead of the image. Take me to the image only if there is no article. Of course this may be more difficult to make happen--I don't know how the site is structured. My web programming is very basic. Still, I think this makes sense from a user's POV.

Thanks in Advance,
[[User:RogerAF|RAF]] 17:26, 22 May 2007 (PDT)

Aloha, Roger.
You're doing great.

I agree that it would be nice if clicking on the picture of the LT1528 took you directly to the article about the LT1528.
I don't know how to fix it.

Do you see the "Help" link in the navigation bar on the left side of every page?
I think the page it brings up needs a few more tips.
But I want to keep it short and simple.
If I explained every detail, it would become a bloated 100-page document that nobody would read.

There are already far too many bloated 100-page documents about electronics.

I hope that you, dear reader, and other volunteers will make Open Circuits into a place where people can learn to do amazing things.
A place that avoids forcing people to learn 100 irrelevant details before learning the one thing they need to know before they get back to building their robot (or whatever).
A place that never makes people throw away good ideas, because we never confuse people into believing that it would be far more complicated and expensive to build than it really is.

p.s.:
Picking the name of a page is a bit of an art.
Since we want to refer to a page a lot, that's easier when the name is very short.
People new to wiki always pick names that are too long, or have too many capital letters.
Fortunately, it's very simple to rename pages.
You rename pages by clicking on the incorrectly-named "Move this page" button.
(I don't know how to fix that, either).
--[[User:DavidCary|DavidCary]] 10:15, 23 May 2007 (PDT)

=== making links ===

Speaking of linkage, making links is one of the most important parts of this wiki.

Whenever you find one article mentioning some other article, you can click on that word to get more detail.

If that word is not already clickable (underlined and colored), please make it clickable.
To make a word clickable, hit the "edit" button at the top of the page.
Then add double brackets <nowiki>"[["</nowiki> and <nowiki>"]]"</nowiki> around that word.
(Some people recommend only making the first mention of that word clickable).

The cheatsheet ( http://en.wikipedia.org/wiki/Wikipedia:Cheatsheet ) calls this an "internal link".

Here's the trick: you can add those brackets to any word, making it into a link.
Some of those links will go to pages that don't exist yet.

What happens when you click on one of those links to a page that doesn't exist yet?

I'm not going to tell you what happens.
Go find out for yourself.
You can practice in the [[meta:Sandbox]].

--[[User:DavidCary|DavidCary]] 10:15, 23 May 2007 (PDT)

----
Aloha David,
Roger again; I want to thank you for the info and hints. I'm catching on. I got my component description linked to the caption under the image on the Components/Voltage Regulators page. And I created a "New Article" which I then "moved" to the title of my article. And my article has a link to the description and that has a link to the article, so I'm getting the hang of it. I have several schematics and PC artwork images to upload and link to my article, plus a second article I want to publish (I didn't write it, but I've been unable to find it on the internet--I have a xeroxed copy from 1986 or so and that is the only existing one as far as I know). That article also has several images that go along with it. I wondered about the feasability of uploading a .pdf file (I made one of it) to this site. Would that work? Should I even try? I don't want to screw anything up, but wouldn't that be a lovely thing if we could upload .pdf files? Just a thought.

Again, Thanks very much, I've made some progress.

[[User:RogerAF|RAF]] 19:48, 23 May 2007 (PDT)

Aloha, Roger.
You are welcome.
Have you tried creating a link to an article that doesn't exist yet, just to see what happens when you click on that link? For example, the [[switching regulator]] page that I'm going to start in a few days.

I don't know about this article that you didn't write.
If the original author wants people to post it widely, and doesn't mind us editing it, then great, let's post it (and give correct attribution).
But some writers go a little crazy when they see that someone random stranger has copied their stuff and posted it to the internet.
(That's why there's that "DO NOT SUBMIT COPYRIGHTED WORK WITHOUT PERMISSION!" note at the bottom of each Edit page).

I wouldn't mind you posting a .pdf file (that you wrote) temporarily.
It's better than nothing.
But I would expect someone to eventually convert it to text-and-images.
That makes it much easier for the next person to improve the it.

Thank you again for adding useful information to Open Circuits.
I hope you won't mind people "improving" the things you post here.

--[[User:DavidCary|DavidCary]] 21:26, 23 May 2007 (PDT)

Aloha David,
Sorry for the delay, I had a loonng job and then our cable modem failed. At least they swapped us a new one free (hooray RoadRunner). But I want to explain the article: "The Many-Talented 723" by Glenn Prescott. I came across this as a xerox copy sometime around 1985. It was evidently published in a magazine for radio enthusiasts--there are some ads on the last page for radio gear. But the name of the magazine isn't on any of the pages. I Googled for the article and got no returns. I think it is a very good article as far as describing the IC and how to use it. It helped me when I was a beginner, so I want to share it. However, I don't want anyone to get into trouble over it. I just did another search on Google and all the returns refer to my mention of it here on Open Circuits. Like I said, this is a copy that I have, no clue as to the magazine that published it, no copyright date, no nothin'. But I will leave it to your judgement if it is a risk. I still have my own article to get uploaded along with images. I will concentrate on getting mine done before doing anything with the copied article.

[[User:RogerAF|RAF]] 20:27, 26 May 2007 (PDT)

Unless the author has given permission to publish it, I think a better idea would be to write your own article, citing the one you're talking about further details. Ideas are not copyright, but the expression of them (i.e. the text of the article) is, or so I understand. [[User:Autarch|Autarch]] 10:22, 13 June 2007 (PDT)

== spammers ==

I think I know how to dramatically reduce the amount of linkspam on the website i think if the administrators on this site protect pages that are frequently spammed such as [[Open Circuits talk:Community Portal]] that will reduce the amount of spam on this site because the spammers will not be able to edit those pages.--[[User:71.234.233.163|71.234.233.163]] 08:21, 2 June 2007 (PDT)

:I just signed up a few minutes ago and noticed that there seems to be a lot of linkspam being placed by unregistered users. I don't want to exclude folk, but would only allowing registered users to edit cut down some of the spam? [[User:Autarch|Autarch]] 09:53, 13 June 2007 (PDT)

::You are right.
::Certainly that is one way to cut down on spam, and perhaps I will be forced to do that soon.

Another way, as you can see from [[Special:Ipblocklist]], I've been banning a bunch of anonymous spammers.

:But is there another, better way to reduce spam?

:I want to avoid a problem I am starting to notice.
:Sometimes I see a tiny little typo or technopropisms or some other tiny little thing that I could easily fix
:( http://communitywiki.org/WhyWikiWorks ).
:But someone has built a huge barrier that prevents me from helping.
:We want a system in a way that makes it very easy for anyone to help us.
:Certainly too much spam is leaking through just now, but I don't want to go to the opposite extreme and make people go through a big complicated procedure in order to improve a schematic or fix a typo.
:--[[User:DavidCary|DavidCary]] 21:39, 21 June 2007 (PDT)

::That's a very noble way of thinking. I also like to be able to edit anonymously... There are enough sites you have to register for already. --SebDE

::I know how to greatly reducethe amount of spam without stopping anomyomus ips from editing you can install a spam filter [http://wiki.cotch.net/index.php/Spam_filter like the one at my website EvoWiki] we usually dont get much spam at EvoWiki because we have a spam filter.--[[User:71.234.233.163|71.234.233.163]] 15:01, 22 June 2007 (PDT)

:::Indeed, a black list based on words is the way to go here. BTW this seems to be an extension you need to install from [http://meta.wikimedia.org/wiki/SpamBlacklist_extension there]
:::And an easy way to monitor for spam can help, too. The spam cops around here might want to check out those [http://en.wikipedia.org/wiki/Wikipedia:Tools/Editing_tools wiki editing tools] ;) --SebDE
::::Bummer, they recently moved the BalckList Extension to the Extension namespace http://www.mediawiki.org/wiki/Extension:SpamBlacklist
::::Anyways, if you've problem with installing that or in doubt of maintaining - I run several mediawikis for private use and am quite advanced with regexes, although only very simple ones are needed for the BlackList.
::::--SebDE
:::::Well I just digged through the code of the Extension and spotted a spam filter option that is already there in the MediaWiki software. It would involve edititing the configuration for any new spam pattern, tough. --SebDE

'''Anonymous Edits?'''
Aloha from Honolulu David,
I just got an email saying my page had been edited by an anonymous user. I don't know who this is, there is nothing his/her page. I would not be complainig if the edits had improved things, but all they did was delete information. Perhaps it is their sense of humor.
I am glad there is the record of changes made, so I can try to recover what was removed. Just to let you know that apparently spammers are not all you have to worry about.

Roger
[[User:RogerAF|RAF]] 05:58, 9 July 2007 (PDT)

P. S.

I just finished replacing what had been rmoved. Again, I'm grateful for the changes records. I also left a note to whoever did it. I think possibly it was unintentional. I hope that's the case.

It occurred to me that perhaps editing should not be allowed by anonymous users. Perhaps there could be a special page that allowed anonimity, but require identification from anyone who wants to perform edits on pages that others have posted.

I don't know how you'd acomplish it. I'm just a bit po'd that this can happen. He could have easily deleted the whole page. I'm glad it was easy to repair, but I will be moving come the middle of August and I may not have email for a week or two, possibly longer. So if something like this happened then, I would not know for some time. Then it would be a problem. Forgive my rant, but see my point? I'll leave it at that and check back later.

[[User:RogerAF|RAF]] 06:23, 9 July 2007 (PDT)

I'm sorry that your page was damaged.
Certainly, blocking "ip users" would have stopped this particular problem.
But is there a better solution?
One that doesn't force people to go through a "identification process" before fixing a little typo?
--[[User:DavidCary|DavidCary]] 14:45, 9 July 2007 (PDT)
:Yes, there is, I already posted this. http://www.mediawiki.org/wiki/Extension:SpamBlacklist
:4 simple steps:
:* Create an article for spam phrases -- I'll pop up more often (even create an account) and help maintaining this list ;)
:* Protect this Article against anonymous edits
:* Install the Extension
:* Configure the extension to use the just created Article (in this example [[spam blacklist]]):
<pre>
require_once( "$IP/extensions/SpamBlacklist/SpamBlacklist.php" );
$wgSpamBlacklistFiles = array(
"DB: $wgDBname spam_blacklist",
);
</pre>
:If you've any questions you can contact me: ogcsisq02@sneakemail.com
:--SebDE

Programmable Chip EEG

2007-07-10T17:47:10Z

204.80.61.114: /* Parts used in the PCEEG: */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in 1168
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring.

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the PIC18 which will, further process the signals, and provide an interface to a computer & lcd display.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using EAGLE CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly]

=== How You Can Help ===
#. get the tools
== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* Eagle CAD could be used in the future after all the parts are surface mount & the analog sections are alalised. To autorout future designs.
* Express PCB is being used to create the first PCB but surface mount must be used to save hole count and space.
* Maxima a computer algebra system s used for graphing and matth displays.

*[[I2C]] interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*SPI interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*migrate from switcher cad to pcb express.
*migrate from pcb express to eagle cad after testing to further development.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the UBW which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 20 bit ADC.

''(In 2007-02, some one claimed "We expect this project to require at least 20 bit ADC." -- why? Many people (*) do EKGs with only 10 bit converters.)''

* $12.00 The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS. It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]
* TI app note [http://focus.ti.com/docs/solution/folders/print/272.html "Biophysical Monitoring: Electrocardiogram (ECG) Front End"] has a simple circuit: 390 KOhm resistors in-line with each lead -- one end touches patient, the other end directly connected to the instrumentation amp input (or the right-leg drive amplifier output, which has no further protection). The inst. amp has 2 protection diodes on each input, directly to +power and -power. Also, 39 pF capacitor from each input to analog GND, and 200 pF between the 2 inputs. The TI publication "Information for Medical Applications" (2Q 2004) reprints that circuit, but leaves out the caps and the diodes.
* (*) [http://www.ieeta.pt/~escadas/ucecg/applications.htm Some people use 420 Hz sampling rate, 10 bits/sample.]
* [http://bsamig.uku.fi/pdf/QRSdet.pdf "High-Resolution QRS Detection Algorithm for Sparsely Sampled ECG Recordings"] by Timo Bragge et. al. 2004 recommends: "the sampling frequency of the ECG should be at least 500 Hz"
* [http://www.analog.com/library/analogDialogue/archives/29-3/low_power.html "Low-Power, Low-Voltage IC Choices for ECG System Requirements"] by Jon Firth and Paul Errico says "The multiplexed architecture, based on an old assumption that the converter is by far the most-expensive front-end component, is prevalent in today's electrophysiological measurement systems. However, with the proliferation of sigma-delta converter architectures, converter-per-channel is now a power- and cost-competitive alternative". It also gives a typical schematic for both architectures and suggests some parts.
* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]?

[[Category:Projects]]

Programmable Chip EEG

2007-07-10T17:46:26Z

204.80.61.114: /* Parts used in the PCEEG: */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in 1168
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring.

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the PIC18 which will, further process the signals, and provide an interface to a computer & lcd display.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using EAGLE CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly]

=== How You Can Help ===
#. get the tools
== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* Eagle CAD could be used in the future after all the parts are surface mount & the analog sections are alalised. To autorout future designs.
* Express PCB is being used to create the first PCB but surface mount must be used to save hole count and space.
* Maxima a computer algebra system s used for graphing and matth displays.

*[[I2C]] interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*SPI interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*migrate from switcher cad to pcb express.
*migrate from pcb express to eagle cad after testing to further development.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly] which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 20 bit ADC.

''(In 2007-02, some one claimed "We expect this project to require at least 20 bit ADC." -- why? Many people (*) do EKGs with only 10 bit converters.)''

* $12.00 The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS. It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]
* TI app note [http://focus.ti.com/docs/solution/folders/print/272.html "Biophysical Monitoring: Electrocardiogram (ECG) Front End"] has a simple circuit: 390 KOhm resistors in-line with each lead -- one end touches patient, the other end directly connected to the instrumentation amp input (or the right-leg drive amplifier output, which has no further protection). The inst. amp has 2 protection diodes on each input, directly to +power and -power. Also, 39 pF capacitor from each input to analog GND, and 200 pF between the 2 inputs. The TI publication "Information for Medical Applications" (2Q 2004) reprints that circuit, but leaves out the caps and the diodes.
* (*) [http://www.ieeta.pt/~escadas/ucecg/applications.htm Some people use 420 Hz sampling rate, 10 bits/sample.]
* [http://bsamig.uku.fi/pdf/QRSdet.pdf "High-Resolution QRS Detection Algorithm for Sparsely Sampled ECG Recordings"] by Timo Bragge et. al. 2004 recommends: "the sampling frequency of the ECG should be at least 500 Hz"
* [http://www.analog.com/library/analogDialogue/archives/29-3/low_power.html "Low-Power, Low-Voltage IC Choices for ECG System Requirements"] by Jon Firth and Paul Errico says "The multiplexed architecture, based on an old assumption that the converter is by far the most-expensive front-end component, is prevalent in today's electrophysiological measurement systems. However, with the proliferation of sigma-delta converter architectures, converter-per-channel is now a power- and cost-competitive alternative". It also gives a typical schematic for both architectures and suggests some parts.
* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]?

[[Category:Projects]]

Programmable Chip EEG

2007-07-10T17:42:06Z

204.80.61.114: /* Open Source Circuit Design */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in 1168
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring.

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the PIC18 which will, further process the signals, and provide an interface to a computer & lcd display.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using EAGLE CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly]

=== How You Can Help ===
#. get the tools
== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* Eagle CAD could be used in the future after all the parts are surface mount & the analog sections are alalised. To autorout future designs.
* Express PCB is being used to create the first PCB but surface mount must be used to save hole count and space.
* Maxima a computer algebra system s used for graphing and matth displays.

*[[I2C]] interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*SPI interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*migrate from switcher cad to pcb express.
*migrate from pcb express to eagle cad after testing to further development.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal
* The [http://opencircuits.com/Digitally_Programmable_Potentiometers Digitally Programmable Potentiometers AD5204] 4-Channel Digitally Controlled Potentiometer is used to make calibration of this device easier. (Historically, a weak point of homebrew designs has been their sensitivity to component value; tolerance and drift have made them require constant tweaking for good results.)

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly] which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 20 bit ADC.

''(In 2007-02, some one claimed "We expect this project to require at least 20 bit ADC." -- why? Many people (*) do EKGs with only 10 bit converters.)''

* $12.00 The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS. It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]
* TI app note [http://focus.ti.com/docs/solution/folders/print/272.html "Biophysical Monitoring: Electrocardiogram (ECG) Front End"] has a simple circuit: 390 KOhm resistors in-line with each lead -- one end touches patient, the other end directly connected to the instrumentation amp input (or the right-leg drive amplifier output, which has no further protection). The inst. amp has 2 protection diodes on each input, directly to +power and -power. Also, 39 pF capacitor from each input to analog GND, and 200 pF between the 2 inputs. The TI publication "Information for Medical Applications" (2Q 2004) reprints that circuit, but leaves out the caps and the diodes.
* (*) [http://www.ieeta.pt/~escadas/ucecg/applications.htm Some people use 420 Hz sampling rate, 10 bits/sample.]
* [http://bsamig.uku.fi/pdf/QRSdet.pdf "High-Resolution QRS Detection Algorithm for Sparsely Sampled ECG Recordings"] by Timo Bragge et. al. 2004 recommends: "the sampling frequency of the ECG should be at least 500 Hz"
* [http://www.analog.com/library/analogDialogue/archives/29-3/low_power.html "Low-Power, Low-Voltage IC Choices for ECG System Requirements"] by Jon Firth and Paul Errico says "The multiplexed architecture, based on an old assumption that the converter is by far the most-expensive front-end component, is prevalent in today's electrophysiological measurement systems. However, with the proliferation of sigma-delta converter architectures, converter-per-channel is now a power- and cost-competitive alternative". It also gives a typical schematic for both architectures and suggests some parts.
* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]?

[[Category:Projects]]

Programmable Chip EEG

2007-07-10T17:23:02Z

204.80.61.114: /* A/D Converters */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in 1168
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring.

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the PIC18 which will, further process the signals, and provide an interface to a computer & lcd display.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using EAGLE CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly]

=== How You Can Help ===
#. get the tools
== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* Eagle CAD could be used in the future after all the parts are surface mount & the analog sections are alalised. To autorout future designs.
* Express PCB is being used to create the first PCB but surface mount must be used to save hole count and space.
* Maxima a computer algebra system s used for graphing and matth displays.

*[[I2C]] interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*SPI interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*migrate from switcher cad to pcb express.
*migrate from pcb express to eagle cad after testing to further development.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal
* The [http://opencircuits.com/Digitally_Programmable_Potentiometers Digitally Programmable Potentiometers AD5204] 4-Channel Digitally Controlled Potentiometer is used to make calibration of this device easier. (Historically, a weak point of homebrew designs has been their sensitivity to component value; tolerance and drift have made them require constant tweaking for good results.)

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly] which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://www.thinkcycle.org/ Think Cycle]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 20 bit ADC.

''(In 2007-02, some one claimed "We expect this project to require at least 20 bit ADC." -- why? Many people (*) do EKGs with only 10 bit converters.)''

* $12.00 The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS. It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]
* TI app note [http://focus.ti.com/docs/solution/folders/print/272.html "Biophysical Monitoring: Electrocardiogram (ECG) Front End"] has a simple circuit: 390 KOhm resistors in-line with each lead -- one end touches patient, the other end directly connected to the instrumentation amp input (or the right-leg drive amplifier output, which has no further protection). The inst. amp has 2 protection diodes on each input, directly to +power and -power. Also, 39 pF capacitor from each input to analog GND, and 200 pF between the 2 inputs. The TI publication "Information for Medical Applications" (2Q 2004) reprints that circuit, but leaves out the caps and the diodes.
* (*) [http://www.ieeta.pt/~escadas/ucecg/applications.htm Some people use 420 Hz sampling rate, 10 bits/sample.]
* [http://bsamig.uku.fi/pdf/QRSdet.pdf "High-Resolution QRS Detection Algorithm for Sparsely Sampled ECG Recordings"] by Timo Bragge et. al. 2004 recommends: "the sampling frequency of the ECG should be at least 500 Hz"
* [http://www.analog.com/library/analogDialogue/archives/29-3/low_power.html "Low-Power, Low-Voltage IC Choices for ECG System Requirements"] by Jon Firth and Paul Errico says "The multiplexed architecture, based on an old assumption that the converter is by far the most-expensive front-end component, is prevalent in today's electrophysiological measurement systems. However, with the proliferation of sigma-delta converter architectures, converter-per-channel is now a power- and cost-competitive alternative". It also gives a typical schematic for both architectures and suggests some parts.
* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]?

[[Category:Projects]]

Programmable Chip EEG

2007-07-10T17:20:09Z

204.80.61.114: /* ESD Protection in 1168 and Max3235E */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in 1168
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring.

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the PIC18 which will, further process the signals, and provide an interface to a computer & lcd display.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using EAGLE CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly]

=== How You Can Help ===
#. get the tools
== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* Eagle CAD could be used in the future after all the parts are surface mount & the analog sections are alalised. To autorout future designs.
* Express PCB is being used to create the first PCB but surface mount must be used to save hole count and space.
* Maxima a computer algebra system s used for graphing and matth displays.

*[[I2C]] interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*SPI interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*migrate from switcher cad to pcb express.
*migrate from pcb express to eagle cad after testing to further development.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal
* The [http://opencircuits.com/Digitally_Programmable_Potentiometers Digitally Programmable Potentiometers AD5204] 4-Channel Digitally Controlled Potentiometer is used to make calibration of this device easier. (Historically, a weak point of homebrew designs has been their sensitivity to component value; tolerance and drift have made them require constant tweaking for good results.)

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly] which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://www.thinkcycle.org/ Think Cycle]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 12 bit ADC.

''(In 2007-02, some pundit made this project seem unnecessarily complicated by claiming "We expect this project to require at least 20 bit ADC." -- why? Many people (*) do EKGs with only 10 bit converters.)''

* $12.00 The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS. It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

What low-cost ADC are available with at least 12 bits?

* $2.50 MCP3301 has 1 ADC input (13 bits)
* $3.50 MCP3302 has 2 ADC input (13 bits)
* $3.50 MCP3204 has 4 ADC input (12 bits)
* $4 MCP3208 has 8 ADC input (12 bits)
* $8 dsPIC30F 2011 microcontroller has 8 ADC inputs (12 bits). See [[dsPIC30F 5011 Development Board]] for details.
* $6 CY8C27443 Cypress PSoC microcontroller has 4 ADC inputs (14 bits) -- but what is the sampling rate? Also has 4 DAC outputs (9 bits).

* $56 biosemi used analog devices AD7716: four independent, simultaneous 22 bit ADCs.
* [http://www.maxim-ic.com/appnotes.cfm/an_pk/885 the Maxim MAX1460 includes a 16-bit ADC, 12-bit DAC], a programmable gain amp (PGA), temp sensor, and 16-bit processor. (Alas, its program is in unchangeable ROM).
* Analog Devices AduC812: 200kHz 12-bit ADC, 12-bit DAC, and flash-based 8051 MCU core.

''I am astonished to discover that (a few) microcontrollers include 12 bit or more ADCs. Are there others?''

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]
* TI app note [http://focus.ti.com/docs/solution/folders/print/272.html "Biophysical Monitoring: Electrocardiogram (ECG) Front End"] has a simple circuit: 390 KOhm resistors in-line with each lead -- one end touches patient, the other end directly connected to the instrumentation amp input (or the right-leg drive amplifier output, which has no further protection). The inst. amp has 2 protection diodes on each input, directly to +power and -power. Also, 39 pF capacitor from each input to analog GND, and 200 pF between the 2 inputs. The TI publication "Information for Medical Applications" (2Q 2004) reprints that circuit, but leaves out the caps and the diodes.
* (*) [http://www.ieeta.pt/~escadas/ucecg/applications.htm Some people use 420 Hz sampling rate, 10 bits/sample.]
* [http://bsamig.uku.fi/pdf/QRSdet.pdf "High-Resolution QRS Detection Algorithm for Sparsely Sampled ECG Recordings"] by Timo Bragge et. al. 2004 recommends: "the sampling frequency of the ECG should be at least 500 Hz"
* [http://www.analog.com/library/analogDialogue/archives/29-3/low_power.html "Low-Power, Low-Voltage IC Choices for ECG System Requirements"] by Jon Firth and Paul Errico says "The multiplexed architecture, based on an old assumption that the converter is by far the most-expensive front-end component, is prevalent in today's electrophysiological measurement systems. However, with the proliferation of sigma-delta converter architectures, converter-per-channel is now a power- and cost-competitive alternative". It also gives a typical schematic for both architectures and suggests some parts.
* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]?

[[Category:Projects]]

Programmable Chip EEG

2007-07-10T17:19:20Z

204.80.61.114: /* Status */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in 1168
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring.

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the PIC18 which will, further process the signals, and provide an interface to a computer & lcd display.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using EAGLE CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168 and Max3235E ==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 and Max3235E datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly]

=== How You Can Help ===
#. get the tools
== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* Eagle CAD could be used in the future after all the parts are surface mount & the analog sections are alalised. To autorout future designs.
* Express PCB is being used to create the first PCB but surface mount must be used to save hole count and space.
* Maxima a computer algebra system s used for graphing and matth displays.

*[[I2C]] interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*SPI interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*migrate from switcher cad to pcb express.
*migrate from pcb express to eagle cad after testing to further development.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal
* The [http://opencircuits.com/Digitally_Programmable_Potentiometers Digitally Programmable Potentiometers AD5204] 4-Channel Digitally Controlled Potentiometer is used to make calibration of this device easier. (Historically, a weak point of homebrew designs has been their sensitivity to component value; tolerance and drift have made them require constant tweaking for good results.)

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly] which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://www.thinkcycle.org/ Think Cycle]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 12 bit ADC.

''(In 2007-02, some pundit made this project seem unnecessarily complicated by claiming "We expect this project to require at least 20 bit ADC." -- why? Many people (*) do EKGs with only 10 bit converters.)''

* $12.00 The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS. It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

What low-cost ADC are available with at least 12 bits?

* $2.50 MCP3301 has 1 ADC input (13 bits)
* $3.50 MCP3302 has 2 ADC input (13 bits)
* $3.50 MCP3204 has 4 ADC input (12 bits)
* $4 MCP3208 has 8 ADC input (12 bits)
* $8 dsPIC30F 2011 microcontroller has 8 ADC inputs (12 bits). See [[dsPIC30F 5011 Development Board]] for details.
* $6 CY8C27443 Cypress PSoC microcontroller has 4 ADC inputs (14 bits) -- but what is the sampling rate? Also has 4 DAC outputs (9 bits).

* $56 biosemi used analog devices AD7716: four independent, simultaneous 22 bit ADCs.
* [http://www.maxim-ic.com/appnotes.cfm/an_pk/885 the Maxim MAX1460 includes a 16-bit ADC, 12-bit DAC], a programmable gain amp (PGA), temp sensor, and 16-bit processor. (Alas, its program is in unchangeable ROM).
* Analog Devices AduC812: 200kHz 12-bit ADC, 12-bit DAC, and flash-based 8051 MCU core.

''I am astonished to discover that (a few) microcontrollers include 12 bit or more ADCs. Are there others?''

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]
* TI app note [http://focus.ti.com/docs/solution/folders/print/272.html "Biophysical Monitoring: Electrocardiogram (ECG) Front End"] has a simple circuit: 390 KOhm resistors in-line with each lead -- one end touches patient, the other end directly connected to the instrumentation amp input (or the right-leg drive amplifier output, which has no further protection). The inst. amp has 2 protection diodes on each input, directly to +power and -power. Also, 39 pF capacitor from each input to analog GND, and 200 pF between the 2 inputs. The TI publication "Information for Medical Applications" (2Q 2004) reprints that circuit, but leaves out the caps and the diodes.
* (*) [http://www.ieeta.pt/~escadas/ucecg/applications.htm Some people use 420 Hz sampling rate, 10 bits/sample.]
* [http://bsamig.uku.fi/pdf/QRSdet.pdf "High-Resolution QRS Detection Algorithm for Sparsely Sampled ECG Recordings"] by Timo Bragge et. al. 2004 recommends: "the sampling frequency of the ECG should be at least 500 Hz"
* [http://www.analog.com/library/analogDialogue/archives/29-3/low_power.html "Low-Power, Low-Voltage IC Choices for ECG System Requirements"] by Jon Firth and Paul Errico says "The multiplexed architecture, based on an old assumption that the converter is by far the most-expensive front-end component, is prevalent in today's electrophysiological measurement systems. However, with the proliferation of sigma-delta converter architectures, converter-per-channel is now a power- and cost-competitive alternative". It also gives a typical schematic for both architectures and suggests some parts.
* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]?

[[Category:Projects]]

Programmable Chip EEG

2007-07-10T17:02:21Z

204.80.61.114: /* PCEEG, What it is and why it can be the best */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in 1168
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 datasheet.

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit, for example, 60Hz noise from nearby A/C power wiring.

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the PIC18 which will, further process the signals, and provide an interface to a computer & lcd display.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using LT switcher CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168 and Max3235E ==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 and Max3235E datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly]

=== How You Can Help ===
#. get the tools
== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* Eagle CAD could be used in the future after all the parts are surface mount & the analog sections are alalised. To autorout future designs.
* Express PCB is being used to create the first PCB but surface mount must be used to save hole count and space.
* Maxima a computer algebra system s used for graphing and matth displays.

*[[I2C]] interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*SPI interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*migrate from switcher cad to pcb express.
*migrate from pcb express to eagle cad after testing to further development.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal
* The [http://opencircuits.com/Digitally_Programmable_Potentiometers Digitally Programmable Potentiometers AD5204] 4-Channel Digitally Controlled Potentiometer is used to make calibration of this device easier. (Historically, a weak point of homebrew designs has been their sensitivity to component value; tolerance and drift have made them require constant tweaking for good results.)

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly] which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://www.thinkcycle.org/ Think Cycle]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 12 bit ADC.

''(In 2007-02, some pundit made this project seem unnecessarily complicated by claiming "We expect this project to require at least 20 bit ADC." -- why? Many people (*) do EKGs with only 10 bit converters.)''

* $12.00 The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS. It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

What low-cost ADC are available with at least 12 bits?

* $2.50 MCP3301 has 1 ADC input (13 bits)
* $3.50 MCP3302 has 2 ADC input (13 bits)
* $3.50 MCP3204 has 4 ADC input (12 bits)
* $4 MCP3208 has 8 ADC input (12 bits)
* $8 dsPIC30F 2011 microcontroller has 8 ADC inputs (12 bits). See [[dsPIC30F 5011 Development Board]] for details.
* $6 CY8C27443 Cypress PSoC microcontroller has 4 ADC inputs (14 bits) -- but what is the sampling rate? Also has 4 DAC outputs (9 bits).

* $56 biosemi used analog devices AD7716: four independent, simultaneous 22 bit ADCs.
* [http://www.maxim-ic.com/appnotes.cfm/an_pk/885 the Maxim MAX1460 includes a 16-bit ADC, 12-bit DAC], a programmable gain amp (PGA), temp sensor, and 16-bit processor. (Alas, its program is in unchangeable ROM).
* Analog Devices AduC812: 200kHz 12-bit ADC, 12-bit DAC, and flash-based 8051 MCU core.

''I am astonished to discover that (a few) microcontrollers include 12 bit or more ADCs. Are there others?''

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]
* TI app note [http://focus.ti.com/docs/solution/folders/print/272.html "Biophysical Monitoring: Electrocardiogram (ECG) Front End"] has a simple circuit: 390 KOhm resistors in-line with each lead -- one end touches patient, the other end directly connected to the instrumentation amp input (or the right-leg drive amplifier output, which has no further protection). The inst. amp has 2 protection diodes on each input, directly to +power and -power. Also, 39 pF capacitor from each input to analog GND, and 200 pF between the 2 inputs. The TI publication "Information for Medical Applications" (2Q 2004) reprints that circuit, but leaves out the caps and the diodes.
* (*) [http://www.ieeta.pt/~escadas/ucecg/applications.htm Some people use 420 Hz sampling rate, 10 bits/sample.]
* [http://bsamig.uku.fi/pdf/QRSdet.pdf "High-Resolution QRS Detection Algorithm for Sparsely Sampled ECG Recordings"] by Timo Bragge et. al. 2004 recommends: "the sampling frequency of the ECG should be at least 500 Hz"
* [http://www.analog.com/library/analogDialogue/archives/29-3/low_power.html "Low-Power, Low-Voltage IC Choices for ECG System Requirements"] by Jon Firth and Paul Errico says "The multiplexed architecture, based on an old assumption that the converter is by far the most-expensive front-end component, is prevalent in today's electrophysiological measurement systems. However, with the proliferation of sigma-delta converter architectures, converter-per-channel is now a power- and cost-competitive alternative". It also gives a typical schematic for both architectures and suggests some parts.
* Is there a [http://www.electronicproducts.com/ShowPage1.asp?SECTION=&PRIMID=&FileName=medtelconf3%2Ejul2004%2Ehtml&ReturnLink=%2FSearch1%2Easp%3FManufacturer%3D%26Keyword%3Dimplantables%26Slot%3D0%26StartNum%3D1%26stype%3D%26year%3D10&MonthYear=Jul+2004 Medical Electronics Forum]?

[[Category:Projects]]

Programmable Chip EEG

2007-06-25T12:23:10Z

204.80.61.114: /* Hardware Overview */

== The Programmable Chip EEG ==
Welcome to the PCEEG Wiki, where everyone can add to this EEG brain-computer interface!

== PCEEG, What it is and why it can be the best ==
* The [http://pceeg.sourceforge.net The Programmable Chip EEG] gets its name because its hardware and software can be adjusted digitaly from a home pc.

* The hardware can be adjusted by [http://opencircuits.com/Programmable_Potentiometers Digitally Programmable Potentiometers]. They are used to set the Gain, and frequency responce.
This is usefull to calibrate multiple analog boards for different EEG tests.

* [http://pceeg.sourceforge.net The Programmable Chip EEG] is a Modular Multi-channel electroencephalograph.

* This can be used for a brain-computer interface with biofeedback using a flex sensor or servo to detect fingure movements.

* The [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, and has internal protection circuitry for the user.

* Several matched [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signals.

* ESD Protection in 1168 and Max3235E
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 and Max3235E datasheet.

* The [http://opencircuits.com/Digitally_Programmable_Potentiometers Digitally Programmable Potentiometers AD5204] 4-Channel Digitally Controlled Potentiometer is used to make calibration of this device easier. (Historically, a weak point of homebrew designs has been their sensitivity to component value; tolerance and drift have made them require constant tweaking for good results.)

* To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

* The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly] which will, further process the signals, and provide an interface to a computer & lcd display.

== Status ==
We currently have a (preliminary?) [[circuit design]] and a (prelimary) [[PCB layout]].
We are using LT switcher CAD to draw the scematic.

== Hardware Overview ==
Here is a diagram of how the analog signal processing boards and the microprocessor board will come together.
[[Image:Pceeg.jpg]]
Here is how the analog signal prossesing board will come together.
[[Image:newpceeghddesign.png]]

Great cows basic and a 18 series pic would work well and be quick to implement. Also that allows for a complete open source system...

==ESD Protection in 1168 and Max3235E ==
Chips have been chosen that fallow the human body model of esd protection this can be seen in the 1168 and Max3235E datasheet.

== Description of How it Works ==
The daughter signal prossesing board is responcible for filtering and digitising the signals from the body, then the signals are passed to the control board that is the motherboard. The motherboard then can pass the signal to a larger computer.

The differential analog signal is amplified by the instramentation amplifier. Then the signal is amplified and conditioned by high pass and low pass filters.

The common mode signal is inverted summed and sent back to the body to decrese common mode signal thsi is done by the driver right leg circuit.

Band reject filters may be added soon in the future.

Then the analog signals are simultaniously digitized and the digital values can be clocked to the controler motherboard.

The controler board that is the mother board of the system and the signal prossesing daughter boards plug into is the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly]

=== How You Can Help ===
#. get the tools
== Software Tools ==
* We are using LT switcher CAD to draw the scematic. This also is a SPICE Simulator used to analize the amplifier design.
* Eagle CAD could be used in the future after all the parts are surface mount & the analog sections are alalised. To autorout future designs.
* Express PCB is being used to create the first PCB but surface mount must be used to save hole count and space.
* Maxima a computer algebra system s used for graphing and matth displays.

*[[I2C]] interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*SPI interface diagram for programmable resistors and a/d converters 12 or more bits with low cost.
*linear switcher cad schematic drawing from PCEEG technology applied to the Open EEG design with improvements.
*migrate from switcher cad to pcb express.
*migrate from pcb express to eagle cad after testing to further development.

== Parts used in the PCEEG: ==
* [http://opencircuits.com/LT1168 LT1168 Programmable-Gain Precision Instrumentation Amplifier] is used to amplify the weak electric signals coming from the brain through electrodes attached to the scalp, etc.
* Several [http://opencircuits.com/LT1114 LT1114 Low Power Precision OP-Amps] are used for amplification and filtering of the signal
* The [http://opencircuits.com/Digitally_Programmable_Potentiometers Digitally Programmable Potentiometers AD5204] 4-Channel Digitally Controlled Potentiometer is used to make calibration of this device easier. (Historically, a weak point of homebrew designs has been their sensitivity to component value; tolerance and drift have made them require constant tweaking for good results.)

To reduce noise in the readout of the analog part of this circuit, a common-mode feedback is passed back into the body by the driver right leg circuit. Band reject filter may also be used (to reject, for example, 60Hz noise from nearby A/C power wiring).

The analog signal prossesing board will digitise the signal and pass the data to the control board. The control board is based on the [http://en.wikipedia.org/wiki/AVR_Butterfly AVR Butterfly] which will, further process the signals, and provide an interface to a computer & lcd display.

== News ==
The design is switching to EAGLE CAD, because the auto-router is excellent for open-source productivity. It will allow the design to evolve faster and with less work with a wider selection of [[PCB Manufacturers]].

Here is a picture of the PCEEG being done in [http://www.cadsoft.de/freeware.htm EagleCAD].
[[Image:Eagle_sample.GIF]]
The eagle cad file is here [[Media:PCEEGHD.zip]]

The ideas and monkey to robot arm interface by [http://www.answers.com/topic/miguel-nicolelis Miguel Nicolelis]is very inspiring. He used implanted electrodes to monitor and allow monkeys to control a robot arm as if it was their own. Could the PCEEG do the same with its electrodes on the scalp. Only the future will show.

== Open Source Circuit Design ==
* [http://opencircuits.com/Programmable_Chip_EEG Open Source Circuit Design ]
* [http://www.thinkcycle.org/ Think Cycle]
* [http://pceegbci.blog.com/ The Programmable Chip EEG Open Source Circuit Design BLog]

== Open source (public) results! ==
PHP will be used to create a database of users and what they sample and choose to share with the open source community.

The database will give statistical analysis on users recordings.

Also the extension of SETI called BIONIC could be used as a distributed library creation of artifacts and data mining.

Please contribute and make the PCEEG a great tool for researching brain computer interfaces.

== A/D Converters ==

The programmable chip EEG needs an A/D converter to convert the analog signal (at the output of the instrumentation amplifier) into digital bits.
We expect this project to require at least 20 bit ADC.

The ads1255 by ti is a great a2d converter it has programmable gain and digital low pass filtering with 24 bits of resolution 30KSPS.

It is a 20-SSOP so it might be able to be soldered by a hotplate or hot air rework tool.

Many Atmel and other microcontrollers have a built-in ADC, but those are at most 10 bit ADC, so that ADC is useless to us -- we are forced to use an external ADC.

What low-cost ADC are available with at least 12 bits?

* $2.50 MCP3301 has 1 ADC input (13 bits)
* $3.50 MCP3302 has 2 ADC input (13 bits)
* $3.50 MCP3204 has 4 ADC input (12 bits)
* $4 MCP3208 has 8 ADC input (12 bits)
* $8 dsPIC30F 2011 microcontroller has 8 ADC inputs (12 bits). See [[dsPIC30F 5011 Development Board]] for details.
* $6 CY8C27443 Cypress PSoC microcontroller has 4 ADC inputs (14 bits) -- but what is the sampling rate? Also has 4 DAC outputs (9 bits).

* biosemi used analog devices AD7716 22 bit

The newest system is a dc amplifier without a high-pass, and all the low-pass filtering is digital

== The Goal ==
Eventually, kits could be sold, if there were interest.
More info is available at the PCEEG SourceForge home page at [http://pceeg.sourceforge.net/ PCEEG sourceforge.net].

----
== See also: ==
* [http://wiki.asiaquake.org/openeeg/published/ The OpenEEG wiki]
* [http://pceegbci.blog.com/ The Open EEG Brain Computer Interface BLog]
* [http://www.larryheadinstitute.com/eeg-training.html EEG Training Seminars]
* [http://pceeg.wikia.com/wiki/Main_Page wiki cities on pceeg]
* [http://pceeg.sourceforge.net pceeg.sourceforge.net]
* [http://www.answers.com/topic/miguel-nicolelis miguel nicolelis]
* [http://maxima.sourceforge.net/ Maxima - a computer algebra system]
* [http://www.scienceprog.com/ digital high pass filters and other circuits]
* [http://hcvl.hci.iastate.edu/cgi-bin/openEyes.cgi human and computer vision lab]
* [[PCB Manufacturers]] such as [http://www.batchpcb.com/index.php www.batchpcb.com]
* [http://vulliard.dyndns.org/~vulliard/ eeg biofeedback "mind machine"]
* [http://freenet-homepage.de/moosec/projekte/simpleeeg/index-Dateien/Page431.htm monolith eeg]
* [http://mindhacks.com/blog/2007/01/meg_scanning_the_bra.html yet another pundit disrespects the EEG]
* [http://www.pololu.com/laser_cutting.html lazer cutting for box & solder paste stencil]
* [http://www.amazon.com/Build-Your-Printed-Circuit-Board/dp/007142783X?tag2=zottmann1-20 Build Your Own Printed Circuit Board]
* [http://www.stencilsunlimited.com/solder_products.php solder paste for surface mount that can be stored at room temperature]
* The thread [http://forum.microchip.com/tm.aspx?m=114626 "amplifying biomedical signals: 150 uA with 16 bit resolution?"] has several op-amp suggestions, and mentions that "a good, low-noise, low-cost, isolated EMG/EEG amplifier is one of the most demanding analog electronics designs."
* [http://www.e-dsp.com/how-to-build-your-own-heart-monitoring-device-a-simple-ecg/ How to build your own ECG device]
* [http://www.alertfocus.com/evidence/music17.php neurofeedback helps musicians improve their musical performances by 13 to 17 per cent.]
* [http://health.groups.yahoo.com/group/biofeedback/ "the World's largest Biofeedback and Neurofeedback Discussion Group"]

[[Category:Projects]]