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• PCBs arrived

  jonathanburjb1 • 07/24/2018 at 05:22 • 0 comments

  I got in my PCBs from china, and all my components from digi-key, and got to work assembling the first prototype. In addition, I got my acrylic for the enclosure, and leather for the strap, but did not get to work on that quite yet.

  After assembling, I uploaded the code, which did not work first try. I then developed some sample code to alternate blinking the LEDs. On a similar note I will mention that using test points on the PCB to upload code was not such a good idea. The intent was to make more room, but when rev 2 gets worked on, I should change that over to some kind of actual connector. The connection between the programmer and the test points was very finicky, so much so that it took a couple tries to successfully get code on the ATTTINY. 

  Here is a video I took of the test code in action (three of the LEDs are out as a result of prolonged exposure to the soldering iron):

  Another short coming of rev. 1 was the switch I put on for power saving. I connected the pull up resistor as well as the switch to GND, leaving the LEDs on all the time, and thus giving no power reductions. The watch will only operate for just over a day without the switch, by way of some simplistic estimated calculations. So, don't go making this yet.

  Yet another potential problem. The pull ups for the i2c bus are underneath either the battery or the ATTINY. This may lead to some major communication issues between the RTC and the ATTINY. This is all a mechanical issue with the layout of the PCB. 

  With almost all of the watch messed up, I conclude this disappointing post. I will keep fiddling with this prototype, trying to get rev 2 to a suitable point. Keep an eye on the project logs, and wait for second revision of the PCB to be released.

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