Difference between revisions of "Modulation Plugin"
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*http://focus.ti.com/docs/prod/folders/print/ts5a1066.html | *http://focus.ti.com/docs/prod/folders/print/ts5a1066.html | ||
*call sample | *call sample | ||
+ | {|border="1" cellspacing="0" cellpadding="5" | ||
+ | |+ Table 3.1 IC Requirements | ||
+ | ! Part No. !! Description | ||
+ | ! Min Temp !! Max Temp !! Min Volt !! Max Volt !! Typ Cur !! Max Cur | ||
+ | |-valign="top" | ||
+ | | [http://ww1.microchip.com/downloads/en/DeviceDoc/70116F.pdf dsPIC30F5011-30I/PT] || uP | ||
+ | | -40<sup>o</sup>C || 85<sup>o</sup>C | ||
+ | | 2.5V <sup>[1]</sup>|| 5.5V | ||
+ | | 145mA || 217mA | ||
+ | |- | ||
+ | | [http://datasheets.maxim-ic.com/en/ds/MAX3222-MAX3241.pdf MAX3232ESE] || RS232 driver | ||
+ | | -40<sup>o</sup>C || 85<sup>o</sup>C | ||
+ | | 3.0V || 5.5V | ||
+ | | 0.3mA || 1.0mA | ||
+ | |- | ||
+ | | [http://www.national.com/ds.cgi/DS/DS3695.pdf DS3695N] || RS485 driver | ||
+ | | -40<sup>o</sup>C || 85<sup>o</sup>C | ||
+ | | 4.75V || 5.25V | ||
+ | | 42mA || 60mA | ||
+ | |- | ||
+ | | [http://focus.ti.com/lit/ds/symlink/dac6574.pdf DAC6574IDGS] || 10-bit Quad-DAC I<sup>2</sup>C | ||
+ | | -40<sup>o</sup>C || 105<sup>o</sup>C | ||
+ | | 2.7V || 5.5V | ||
+ | | 0.6mA || 0.9mA | ||
+ | |- | ||
+ | | [http://www.semiconductors.philips.com/acrobat/datasheets/74HC_HCT14_3.pdf 74HC14D] || Quad-Schmitt Trigger | ||
+ | | -40<sup>o</sup>C || 125<sup>o</sup>C | ||
+ | | 2.0V || 6.0V | ||
+ | | || 0.02mA | ||
+ | |- | ||
+ | | '''Overall''' || | ||
+ | | '''-40<sup>o</sup>C''' || '''85<sup>o</sup>C''' | ||
+ | | '''4.75V''' || '''5.25V''' | ||
+ | | || '''<300mA <sup>[2]</sup>''' | ||
+ | |- | ||
+ | | [http://ww1.microchip.com/downloads/en/DeviceDoc/70165E.pdf dsPIC33FJ128GP306-I/PT] || uP | ||
+ | | -40<sup>o</sup>C || 85<sup>o</sup>C | ||
+ | | 3.0V <sup>[1]</sup>|| 3.6V | ||
+ | | 74mA || 250mA | ||
+ | |- | ||
+ | | [http://www.analog.com/UploadedFiles/Data_Sheets/ADM3485E.pdf ADM3485EARZ] || RS485 driver | ||
+ | | -40<sup>o</sup>C || 85<sup>o</sup>C | ||
+ | | 3.0V || 3.6V | ||
+ | | 1.1mA || 2.2mA | ||
+ | |- | ||
+ | | [http://ww1.microchip.com/downloads/en/DeviceDoc/21203N.pdf 24LC256-I/SN] || 256kBits I2C EEPROM | ||
+ | | -40<sup>o</sup>C || 85<sup>o</sup>C | ||
+ | | 2.5V || 5.5V | ||
+ | | 400uA || 3mA | ||
+ | |- | ||
+ | | [http://www.national.com/ds.cgi/LM/LM3940.pdf LM3940IMP-3.3] || 5V-3.3V Regulator | ||
+ | | -40<sup>o</sup>C || 125<sup>o</sup>C | ||
+ | | 5.0V || 7.5V | ||
+ | | 10mA || 250mA | ||
+ | |- | ||
+ | |} | ||
+ | |||
===op-amp buffer=== | ===op-amp buffer=== |
Revision as of 02:18, 9 July 2008
Contents
ToDos
- make sure each components freq. response, to make sure the highest freq.
- place DAC into this module board together, then only 4 wires(Vcc, I2C clk, Gnd & I2C data) from host.
- understand all components
- call sample
- draw circuit and PCB and grounding problem
- test by real circuit and firmware
Objectives
- The modulation module is used to deliver a digital output signal with the following characteristics:
- Square wave
- Variable frequency (>1kHz)
- Variable amplitude (0V - 2.5V)
- interface to MCU which do the control
Q: Is square wave where the "Lo" time is always at "GND" OK?
Q: If not, is a switch between "Lo is GND" vs. "Lo is negative Hi" OK? Or does "Lo" need to be independently controlled with another ADC?
Q: Will people be connecting a speaker directly to the output, requiring a relatively high-power output op amp such as the LM386N-3 ?
Software Solution
- Timer Interrupt controlling I2C 10-bit DAC can only achieve frequency response of about 1kHz
- 5byte/cmd
- 8bit/byte
- baudrate = 400kHz
- This yields 10kHz (0.1ms)
- As OS context switch is 10ms, set timer to 1ms (1kHz), so that 0.9ms can be used to process other tasks
- Due to higher freq. response requirement, so using hardware to implement the clock
Hardware Solution
Circuit
+-----+ +--------+ +--------+ I2C Bus | | | Analog | | Op-Amp | ------------+-----| DAC |------------| Switch |---------| |---------Output | | | +--------+ +--------+ | +-----+ | | | | +--------------+ | | | Programmable | | +-----| Clock |-------+ +--------------+
This architecture allows the square wave to run at a very high frequency, even with a slow I2C and a slow DAC.
Circuit Simulation by Paul Falstad's Web
- Import the following
$ 1 5.0E-6 16.817414165184545 64 5.0 50 w 128 256 144 256 0 w 16 256 64 256 0 g 16 352 16 368 0 v 64 64 112 64 0 0 40.0 2.5 0.0 0.0 0.5 w 112 128 144 128 0 w 64 128 16 128 0 w 16 128 16 256 0 v 64 256 128 256 0 2 1000.0 1.65 1.65 0.0 0.5 a 336 144 464 144 1 3.3 0.0 w 336 160 336 192 0 w 464 192 464 144 0 w 464 144 512 144 0 r 592 144 592 256 0 1000.0 g 592 352 592 368 0 w 512 144 592 144 0 w 336 192 352 192 0 w 432 192 464 192 0 v 64 128 112 128 0 1 1.0 1.25 1.25 0.0 0.5 w 16 256 16 288 0 w 16 288 16 352 0 w 592 256 592 352 0 g 272 352 272 368 0 w 272 128 336 128 0 w 176 256 176 144 0 r 272 224 272 288 0 1000.0 w 272 128 272 224 0 w 272 288 272 352 0 159 144 128 208 128 0 r 208 128 256 128 0 1000.0 w 256 128 272 128 0 w 144 256 176 256 0 r 336 224 336 288 0 1000.0 g 336 352 336 368 0 w 336 288 336 352 0 w 336 192 336 224 0 r 352 192 432 192 0 1000.0 o 4 64 0 34 2.5 7.8125E-4 0 -1 o 0 64 0 35 5.0 9.765625E-5 1 -1 o 11 64 0 34 2.5 0.0015625 2 -1
Components Inside Circuit
DAC chip
- datasheet -- http://focus.ti.com/lit/ds/symlink/dac6574.pdf
clk chip
- datasheet -- http://focus.ti.com/docs/prod/folders/print/cdc706.html
- call sample first, later to buy at -- http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-21381-5-ND
analog switch
Part No. | Description | Min Temp | Max Temp | Min Volt | Max Volt | Typ Cur | Max Cur |
---|---|---|---|---|---|---|---|
dsPIC30F5011-30I/PT | uP | -40oC | 85oC | 2.5V [1] | 5.5V | 145mA | 217mA |
MAX3232ESE | RS232 driver | -40oC | 85oC | 3.0V | 5.5V | 0.3mA | 1.0mA |
DS3695N | RS485 driver | -40oC | 85oC | 4.75V | 5.25V | 42mA | 60mA |
DAC6574IDGS | 10-bit Quad-DAC I2C | -40oC | 105oC | 2.7V | 5.5V | 0.6mA | 0.9mA |
74HC14D | Quad-Schmitt Trigger | -40oC | 125oC | 2.0V | 6.0V | 0.02mA | |
Overall | -40oC | 85oC | 4.75V | 5.25V | <300mA [2] | ||
dsPIC33FJ128GP306-I/PT | uP | -40oC | 85oC | 3.0V [1] | 3.6V | 74mA | 250mA |
ADM3485EARZ | RS485 driver | -40oC | 85oC | 3.0V | 3.6V | 1.1mA | 2.2mA |
24LC256-I/SN | 256kBits I2C EEPROM | -40oC | 85oC | 2.5V | 5.5V | 400uA | 3mA |
LM3940IMP-3.3 | 5V-3.3V Regulator | -40oC | 125oC | 5.0V | 7.5V | 10mA | 250mA |
op-amp buffer
- OPA340