VERY interesting, and a cute choice of project!
Unfortunately, it also confirmed for me that the ez430's protocol of choice is SimpliciTI, not Zigbee or XBee, and thus not available to me. Oh well, thanks for filling that in.

Correction: "868-MHz Access Point has a 0 Ohm resistor next to the antenna and the 915-MHz version doesn't."

I can't find the way to select frequency :S

Amen

@reemrevnivek<br />
I believe 433 is also legal (or can be) in the US - very common for garage door openers.<br />

One big issue is that the Gumstix was operating at a frequency much faster than the watch could handle, so I had to slow the Gumstix's communications down so the watch could pick it up. That solved my problems. I believe the watch has a max clock speed of 25MHz? So it won't be able to handle communications faster than that.

Now I'm trying to get it working with my Beaglebone...

Yes, this is true. Check TI's official wiki, which says under the development software heading:

Although there are many other compiler and integrated development environments for MSP430 including the Rowley Crossworks, MSPGCC and MSPGCC4, the two main options supporting the eZ430-Chronos are IAR Embedded Workbench KickStart and Code Composer Studio. Both IAR and CCS have free code-limited versions supporting the Chronos. The projects for Chronos are delivered in both full source and pre-compiled library options to avoid any code size restrictions.

It's nice that they provided 'pre-compiled library options' for users of the free versions, but it's really rather pointless for hacking on because it means you can't modify the core. Further, 'the two main options' actually means there's no support in the code for other compilers. One other issue not mentioned there is the use of a proprietary BlueRobin binary blob in the firmware, which takes up a lot of space and isn't open.

There is, however, mspgcc, which is not code size limited. Note: this isn't mspgcc4, that page says 'mspgcc4 is no longer supported. All contributions have been incorporated into mspgcc, which has newer versions of all components'.

mspgcc can be used to build the Openchronos-ng and Openchronos projects, which are much better IMO. Based on a comparison of the project commits-per-month stats at Ohloh (Openchronos stats, Openchronos-ng stats), I'd recommend using the Openchronos-ng project going forward. It's under active development, and once you get the development environment set up it's very easy to add your own apps, called 'modules', to the watch.

It's not as easy to use or as open as an Arduino or Beagleboard. If I were in your shoes, I'd add a link to openchronos-ng, mspgcc, and a tutorial on setting that up. I'd avoid adding links to the code-limited compilers and default projects; that just leads to would-be hackers buying this watch and running the stock firmware because they can't change it.

Did you confirm that Sir ?

Which is the most convoluted definition of '30m waterproof' possible. But that's standard for watches and other devices.

I can say that I've had this watch for about a year now and have worn it swimming, running in the rain, and in the shower dozens of times without damage. Occasionally, I'll notice that I'm getting condensation within the watch, so I take it apart, let it dry, and re-seat the O-ring behind the metal back plate with a bit of dielectric grease.

Watch water proofness codes are, as the Wikipedia article says, not intended to actually mean they're waterproof to a given depth:

An indication of the test pressure in terms of water depth does not mean a water resistant watch was designed for repeated long-term use in such water depths. For example, a watch marked 30 metres water resistant cannot be expected to withstand activity for longer time periods in a swimming pool, let alone continue to function at 30 meters under water. This is because the test is conducted only once using static pressure on a sample of newly-manufactured watches.

but it seems that everything you get nowadays is 30m. I buy cheap Timex Ironman watches (and this one, for doing neat stuff like running openchronos-ng apps) and use them in the water. Haven't lost any to water intrusion yet, but I wouldn't be in danger (ie, no scuba diving) or in financial trouble if I did.