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Wrist watch project

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I've now got the first batch of the 250 SPI B/W small LCD displays that I ordered, but I'm not quite sure what to do with them. The obvious thought is a booster pack, but since this is quite a small display I'm thinking maybe I could make a watch kit with it. I might also make some booster packs eventually.


The display data sheet is here. It is SPI-based, but it uses a 9-bit SPI interface. The first bit is decides whether it's a write to the display memory or a config-command. As far as I understand, the USCI-chips don't support 9 bits, while the USI ones do. I've made a bitbanging driver for it so far, and it works ok. I guess with an HW-driver it'll be updating faster. I'll see if maybe it can be tweaked onto the USCI peripheral by sending 2 bytes.


The features are:


- small (34 x 30 mm physical size. Viewing area 28x19)

- 3-line SPI 9-bit (Driver Sitronix ST7579-G2)

- low power

- backlight

- black and white LCD

- approx 3 USD cost


I made a watch with the earlier LCD display (i2c-version) I was using. Here's a picture. The SPI-display is slightly smaller, but the display quality is similar (slightly better on the SPI display). I will have 250 of these, so if anyone is interested in this display for projects, let me know. I'm planning on making some packs that are finished soldered and can be sold in the shop, but it's relatively easy to solder these displays onto a board for your own projects also.




So I'm planning on making a watch-board for the new display. It'll have the display soldered onto one side. The other side will have space for example for a MSP430G2452. The design will be open source. Any suggestions to peripherals and buttons? I could put an accelerometer there, for example to detect taps on the display. I guess I could also put a radio in it???


Edit: Have changed the picture file to a newer version.





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It's printed on shapeways.com. I made a quick 3d model and sent it there for printing. The quality is much nicer than my own home 3d-printer, which I wasn't able to get sufficiently good looks to want to wear on my hand. On the other hand, this would always be a geek-watch I guess, so maybe style isn't what I should be looking for.

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  • 2 weeks later...

Wow that looks really nice. I was thinking of doing something similar with some nokia 1201 displays I have around the place.


You may be able to utilize capacitive buttons, Not sure how well they would work on a watch.


If you want an idea for a new revision a buzzer would add a handful of functionality, feed back for alarms, timers, button presses etc.

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Yes, good idea. Have ordered a first board version to test it out. Several issues I would like to improve, but need to test it a bit first. Like battery mount. Not sure what best low cost option is. Considering a small rechargable battery. The board has solder points, so I can attach a buzzer. It also works as a breakout board for the display.


Cap touch buttons would be nice due to price, but not sure where to put them. How low power would they be?

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The case is a difficult one. I could 3d-print it as before, but it would make a kit more expensive. Yet, having a nice looking case for the watch makes the project much nicer.


I've been wondering since greeg's post how one might be able to do a cap touch button for it. Maybe I could make the top of the case a PCB, with a hole in it that shows the display? So that I can have cap-touch buttons around the screen. I wonder how thin these buttons could be and still work. Might be worth making a drawing of how it'd look at least.


I could also use flexible PCB I guess.

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Hmm I haven't done much with cap buttons except for buy a cap-touch booster pack. But they might operate through the fabricated case. As for power consumption it shouldn't add much more to a MSP running as an RTC.


Here is alot of information on the pinosc feature which would be the easiest way to add cap sensing to your watch: http://processors.wiki.ti.com/index.php/MSP430_Low_Cost_PinOsc_Capacitive_Touch_Overview


It will knock out 1 of your timers but you can use a 2nd timekeeping timer for interval measurement and for timekeeping.


Note there are some useful PDFs at the end of that wiki page.



Just out of curiosity how much did shapeways actually cost? I've been looking for awhile but have never finished a model to try it out.

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  • 3 weeks later...

I assume you have seen the Chronos CC430 watch evaluator. I think your screen is much superior to the segmented screen on the Chronos, but maybe you could retrofit? The CC430 is a pretty good chip, and the Chronos watch design is pretty nice apart from the display. In any case, I would check it out.

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Yes, I've seen it. Have done quite a few projects on it. It's really what inspired me to make my own. And you are right that there are several things that are good about the Chronos:


- battery-life is better on the type of segmented LCD the Chronos has

- many sensors

- nice physical design

- price is very low. They sold it at TI-deals for 25 USD, and it's hard to beat that price.


It's a very good platform for doing fun projects.

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That watch looks nice...


If there's a way to include a vibrating alarm, it cold be a nice plus.


Also, some kind of cyclical beeper would be nice. I've actually bought my Chronus just to have something to softly beep each 5 minutes (or something else programmable) a given number of times. Think in exercise routines, kitchen tasks, meditation... the list of things that need to be repeated every x minutes and just need a soft reminder...


Also if you take a look at the OpenChronos FW, you could adapt the astronomical version to show moon phases graphically...



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  • 1 month later...

One of my favorite watches ever was a casio tough solar. If TI, or you , put solar panels around the bezel..wow. A chronos that never died. Plus, it cost as much as the Chronos does regularly.


A vibrating alarm is REALLY power hungry. a louder speaker would be nice though... NFC would be nice too... There i go again, dreaming...

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