Editing Watch display

The display is perhaps the most critical part of a wrist computer such as the [[uWatch]] and the [[Open Source Watch]].

The [http://www.calcwatch.com/history.htm history of the uWatch] mentions the 53mm x 20mm compact 16x2 line LCD that convinced David L. Jones that the uWatch project was actually doable with off-the-shelf components.
If you are doing low-level programming of the uWatch, such as making "custom characters", you might want to look at [http://www.electusdistribution.com.au/products_uploaded/QP-5519-2.pdf the datasheet] (via [http://www.calcwatch.com/forum/viewtopic.php?id=37 "Moon Phases"]).

Alas, that original display pulls about 2 mA, more power than anything else on the uWatch -- even the CPU uses less power (at 250 KHz). That's the main reason the current uWatch cannot [http://www.calcwatch.com/forum/viewtopic.php?id=42 run the display continuously] (like a standard watch), but much be explicitly "turned on" every time you want to read the time.

The current uWatch2 rough draft seems likely to use the
[http://www.newhavendisplay.com/index.php?main_page=product_info&cPath=3_113&products_id=1824&zenid=goih7iect56osjf64srb498qi4 Newhaven NHD-C12832A1Z-FSW-FBW-3V3] 128x32 Pixels display.
Which uses less than 100uA which would enable a continuous display watch. The "white LED backlight" uses 30 mA at 3.0 V but is still very usable at much lower currents.

There's some discussion of some of the screens considered for the first iteration of the Open Source Watch at http://oswatch.org/details_screen.php .

Proposed displays:
Limited to less than 10 mW of power when updating the time once a second (FIXME: reduce this limit and prune higher-power displays when this list gets too long):
In no particular order:

* [http://www.newhavendisplay.com/index.php?main_page=product_info&cPath=3_113&products_id=1824&zenid=goih7iect56osjf64srb498qi4 Newhaven NHD-C12832A1Z-FSW-FBW-3V3]: 128x32 pixel display, white LED backlight, 41.4mm x 24.3mm (current top runner)
* [http://www.newhavendisplay.com/index.php?main_page=product_info&cPath=21_96&products_id=2072 Newhaven NHD-12864WX-T1TFH# Graphic LCD]: 128x64 pixel display, white LED backlight, 38.0mm x 26.4mm. Power: 3.3 V at 0.18 mA typical (when 32 mA backlight is off)
* [http://www.crystalfontz.com/products/12864ap/index.html CFAX12864AP1 Graphic LCD]: discontinued, apparently replaced by CFAX12864T1.
* [http://www.crystalfontz.com/product/CFAX12864T1WFH.html CFAX12864T1-WFH Graphic LCD]: 128x64 display with EL backlight. Power: 3.3 V at 0.18 mA typical; (the EL backlight version seems to require less power than the [http://www.crystalfontz.com/product/CFAX12864T1TFH.html white LED backlight version]; but how much power is that exactly?).
* [https://www.crystalfontz.com/product/cfax12864t1tfh-graphic-lcd-128x64-display#datasheets CFAX12864T1-TFH Graphic LCD]: 128x64 graphic LCD display with white LED backlight. Power: 3.3 V at 0.18 mA (when 3.5 V at 32 mA backlight is off)
* [http://www.avesodisplays.com/products/index.html card display]: 6 digit, 7 segment display module designed to fit inside a credit card. lightest-weight display of those on this list; adequate for 4-function calculator watch. Doesn't seem to show enough information for a scientific calculator.
* [http://www.sparkfun.com/commerce/categories.php?c=76 Sparkfun LCD displays]: the color graphics LCD cell phone displays look relatively low power and are extremely well documented -- some of them are under $20.
** [https://www.sparkfun.com/products/10168 Graphic LCD 84x48 - Nokia 5110]: power: the datasheet says 2.7 V to 3.3 V at 0.24 mA typical; but the [https://learn.sparkfun.com/tutorials/graphic-lcd-hookup-guide "Graphic LCD Hookup Guide" tutorial] says 2.7 to 3.3V at 7 mA (?) (when the 3 V at 100 mA white backlight LEDs are off) ... [https://learn.adafruit.com/nokia-5110-3310-monochrome-lcd Adafruit: Nokia 5110/3310 Monochrome LCD tutorial]
** [https://www.sparkfun.com/products/11676 Serial Miniature OLED Module - 1.5" (μOLED-128-G2-GFX)] : 128 x 128 resolution, 65K colors, 1.5". Power: 5 V at 60 mA typical when on, 0.1 mA when all pixels black (?). Includes microSD socket.
** [https://www.sparkfun.com/products/11377 Serial Miniature LCD Module - 1.44" (uLCD-144-G2 GFX)] : 128 x 128 resolution, 65K colors. Power: 5 V at 40 mA typical when on, 0.5 mA when all pixels black (?). Includes microSD socket.
** [https://www.sparkfun.com/products/256 Basic 20x4 Character LCD - Black on Green 5V] : Power: 5 V at 1.5 mA typical (when the 4 V at 250 mA LED backlight is off)
** [https://www.sparkfun.com/products/13192 SHARP Memory Display Breakout - Silver Monochrome (1.3", 96x96)] : Power: 12 uW (?) 2.7 V to 3.3 V updated at 1 Hz. Apparently several libraries: [https://github.com/olikraus/u8glib U8glib: A graphics library with support for many different monochrome displays]; [https://github.com/pabigot/bsp430/blob/next/src/boosterpack/sharp96/u8g_bsp430.c]; [https://github.com/adafruit/Adafruit_SHARP_Memory_Display]; ...
* ...
* [https://www.adafruit.com/products/1673 Adafruit LCDs & displays] has a huge list; a few of them are low-power enough for an always-on wristwatch display (have I missed any?):
** [https://www.adafruit.com/products/1393 "SHARP Memory Display Breakout - 1.3" 96x96 Silver Monochrome"] : Power: 12 uW (4 uA at 3.3 V with 1 Hz data refresh)
** [https://www.adafruit.com/products/250 Graphic ST7565 Positive LCD (128x64) with RGB backlight + extras - ST7565] : Power: 3.0 V at 1 mA (when the 5.0 V at 120 mA backlight is off) (What exactly is the difference between this and the [https://www.adafruit.com/products/438 "Graphic ST7565 Negative LCD (128x64) with RGB backlight + extras - ST7565"]?)
** [https://www.adafruit.com/products/398 "RGB backlight positive LCD 16x2 + extras - black on RGB"] and [https://www.adafruit.com/products/399 "RGB backlight negative LCD 16x2 + extras - RGB on black"]. Is this really 2.7 V to 4.5 V at 0.3 mA ? (When R, G, and B LEDs are turned off).
* ...
* ... ''Have you seen a display that would work on a wrist calculator? Please add it to the list here!'' ...

Some threads discussing diplays:
[http://www.calcwatch.com/forum/viewtopic.php?id=7 "Hardware Stuff » Why not a smaller LCD..."],