Project Update 12/2023

I have successfully completed assembly of revision 2 thanks to a sponsorship from PCB way. I have used JLC PCB for all my PCB prototyping over the years up till this point, however, I was pleasantly surprised at the equivalent quality, turn around time, and cost of boards offered by PCB way. Their sales reps were very nice to communicate with and answered all question I had regarding the ordering process. 

After soldering all components onto the board and a thorough cleaning, I performed continuity checks before first power up and everything measured good. For the first time ever on an electronics project involving a microcontroller, I was actually able to flash the bootloader and source code successfully upon first try with no major issues. 

Currently, the only existing issue is that the onboard 32KHz crystal that is for the SAMD21 does not appear to be functioning, therefore when the board config in Arduino IDE is set to use an external oscillator, the chip for some reason does not work properly and I can't read data from the serial port. 

When internal oscillator is selected when uploading the code, the microcontroller works properly and I can retrieve the power monitoring statistics over serial com port. 

I suspect the 32KHz crystal is not functioning either due to being overheated during to solder reflow process, or I do not have the correct load capacitance chosen for the crystal. 

I derived the necessary load capacitance from Adafruits schematic of the Metro M0 board, which uses nearly an identical SAMD chip and layout. The chosen crystal load capacitor in that design is 22pF.

I will have to either replace the crystal of capacitors to see if I can get the clock to be stable and SAMD chip to function properly.