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eZ430 Development Tool Overview Slide 15

Even though the eZ430 programmer is included with the Chronos, TI also added a functionality to wirelessly update the firmware on the Chronos. This allows the user to update the watch without taking it apart. Every MSP430 device has a section of memory that is called the BSL:, or boot strap loaded, memory. Inside of that BSL memory, there is a small RF protocol stack. So once the user goes into that memory, it switches over the application to execute out of the BSL, it starts looking for a receiver that has a valid firmware, and once it finds one, it downloads, installs and erases whatever was running on it before. There are many advantages to using the RF BSL, or wireless update feature, most importantly because it is really fast. Compared to using the eZ430 programmer, it is approximately ten times faster. As an example, downloading a full application wirelessly on the Chronos will only take about ten to fifteen seconds. If the user had to use the complier to download it, because it has to compile and write the Flash over the two-wire interface, it can take anywhere between a minute or two. Additionally, one of the biggest advantages is that the user does not have to disassemble the watch. The downside to this is that there is no debug capability. The pre-compiled binary or hex file is wirelessly downloaded to the watch and the only way to debug is testing how it runs in the application. If it does not work the user would have to go back to the compiler, modify the code and repeat the process. If the user is utilizing the emulator, on the other hand, hardware break points can be used to modify things in real time to try and debug the application. Another downside is that it is a bit of a power hog. Keeping the RF transceiver on full blast for ten to fifteen seconds will consume a good amount of power since RF is the highest source of the power drain on the watch overall. Finally, as mentioned earlier, the first production units did not have the RF BSL built in, but it can be added.

PTM Published on: 2011-07-05