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coredump-ch / nixie-counter

"People present" counter for SpaceAPI, using nixie tubes.
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Power supply for blue pill #1

Closed dbrgn closed 4 years ago

dbrgn commented 4 years ago

It would be nice if we could avoid having to power the blue pill through USB.

Maybe re-use the adjustable regulator board from the iC880A backplane project.

dbrgn commented 4 years ago

Argh, it gets a bit complicated.

I first added a 3.3V 800mA LDO for the Blue Pill and the ESP8266, but then realized that the 5V output of the Blue Pill (required for the logic level of the BCD chips) does not work when not plugged in via USB.

I then replaced the LDO with a 5V version, in order to power the Blue Pill through that LDO directly. The issue now is that the regulator on the Blue Pill will only output 300 mA. For the ESP8266, it is recommended to be able to provide at least 300 mA continuously, but it would have to share that with the Blue Pill.

It's all less than ideal... We could of course add two LDOs, one for 5V and one for 3.3V, both powered by the 12V PSU.

Alternatively, we drop the blue pill completely (it is overkill) and use something like an ESP8266, ESP32 or PADI IoT Stamp (RTL8710), but with the firmware written in C instead of Rust.

What do you think, @rnestler?

dbrgn commented 4 years ago

For the record, I'll simply add a second LDO.