Daniel HeCommit 13a81ae
First prototype. Based on the reference design provided by Arribada. RF traces are calculated with JLC2313 stackup. PCB manufactured by JLCPCB.
Assembled board weighs less than 2g.
What worked:
- Microcontroller
- Power regulators / switch
What didn't work:
- Solar charging
- SPI flash
Apparantly, the "optional" MPPC function on the solar charger IC was not so optional after all.
I also messed up the symbol for the flash chip. The datasheet listed the BGA balls bottom-up, I assumed it was top-down.
Discussions
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Hi Daniel, this is an interesting project - thanks for logging it! I feel for you ref the BGA diagram - I do that sort of thing all the time. What solar cells are you using?
Are you sure? yes | no
I ordered some custom cells trimmed to the same dimensions as the PCB so they can be directly soldered to the back in the final product. Specs are ~1.8V open circuit, ~20mA short (best case scenario).
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Oh nice, looking forward to seeing them. Where did you order custom cells from?
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