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I am looking for a wrist-wearable development platform solution with the following specs:

  • Some kind of a display that you can see in the dark as well as in bright sunlight.
  • Hardware buttons (as opposed to touch-screen).
  • User-programmable on the CPU level (ideally in C).
  • ANT+
  • WiFi
  • Low-power
  • Low-cost
  • CPU does not have to be awfully fast, 100MHz would be plenty
  • Somewhat documented interface with working examples
  • It would be nice if the board could run Linux
  • It would be nice if it also had a GPS chip
  • Something that can be mass-produced at some point to turn into a commercial product.

The best I've been able to find on the market is so far Motorola's MotoACTV which becomes an OK development platform once you root it, but it has a few problems:

  • Definitely not low-power. With display on, and WiFi/GPS/Ant+ sensors off, it lasts maybe only 8 hours. With GPS on only 3.
  • To interface with display and buttons you pretty much have to go through Android as bypassing it creates some serious hurdles - mostly due to the lack of documentation/examples.
  • ANT+ interface is a beast to get working as you have to reverse engineer a lot due to the lack of documentation. I have made some progress there, but have not yet been able to actually obtain the signal.
  • With GPS you are stuck with the Motorola driver which has some serious issues - sometimes it takes 30 minutes to get the signal, then the signal is often not very accurate. I have made an effort to bypass it and write my own, made some progress, but this is another uphill reverse-engineering battle again to due the lack of documentation/examples.
  • Even if I get everything to work perfectly, this is not a viable commercial development platform.

Ti has Chronos EZ-430 which is sort of in the area, but it is lacking some capabilities. It might be possible to instrument it with WiFi/Ant+, but if so, I lack the hardware expertise.

Any ideas on how to build my "dream" gadget would be appreciated - either pre-made product, or a list of parts/instructions how to put them together including the box/wrist-band to make it wrist-wearable.

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    I'm not familiar enough with this kind of hardware, but have you looked at all at what Adafruit offers? They have quite a few products that might be a fit. Of course its something you'd have to build yourself.
    – user1691
    Jun 15 '16 at 21:46
  • There are a lot of raw components on the market, and I am sure with enough hardware experience you can easily tell which ones you will need for this project and how to connect them. What I am looking for is some specific hardware expertise - what exactly to get and what to connect to what. Jun 16 '16 at 1:50
  • I don't think this is the place to find how-to guides, though.
    – user1691
    Jun 16 '16 at 13:34
  • Did you every find something? ESP32 would probably do it, except for the GPS. You can buy a wrist mounted M5stack ESp32 with display for under $115 Oct 19 '19 at 12:06
  • Sorry, typo. That ought to have said under $15 Mar 18 at 13:57
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$14.95 will get you this:

enter image description here

It has a plug & play Grove connector, so you can easily add on GPS for a further $12.

If you can live without GPS, or can solder, then I also recommend LilyGo.

They have a slim wristband, like an activity tracker for about $20:

enter image description here

and a wristwatch with a larger screen for about $25:

enter image description here

All three of these are ESP32 based, so have WiFi and BlueTooth, and are fully programmable.

If, like me, you are allergic to soldering, the M5stack has a Grove connector which allows plug & play of 300+ sensors, motors, etc

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