Eon Smart Watch – 13/5/14

Its been a long time since I last did an update about this but today was a great day for progress! I gave it a bit of a rest because my design was a bit dodgy and I forgot to bring out the SWO pin (PB3) but after more in depth research, it turns out you don’t need this! Another minor problem is that I routed a ground plane under the switching regulator so the ground is pretty noisy but otherwise, most seems ok! I’ve started to redevelop the program completely as I originally programmed it for an STM32F0 yet the chip I’ve used on these PCB’s is an STM32F1. As stupid as it is, it turns out they have nearly completely different standard libraries! The F1 is much much simpler than the F0 and doesn’t have as many features (unfortunately, one of the features I’ll miss most is the RTC calendar feature!). Regardless, today I got it to work from the battery displaying the correct time, wahoo!

My atrocious analog clock face and scrawny arm. Not the easiest to read when static but you can see its roughly 7:04. The second hand rotates normally!

On the side view, you can see how large it is! The final Mk1 version won’t be this thick, its only for easy access underneath the LCD.

The main revisions now will probably be changing the IC from STM32F1 to STM32F0 as not having a calendar feature is a bit fatal for a watch and implementing it in software is somewhat unnecessary if another chip of around the same price provides the feature in hardware. The new series of STM32 chips are really great and some of the F0 series come in TSSOP packages which I find a ton easier to solder than QFP.


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