I've been using ESP32s and ESP8266 for a few years now and I thought I'd give these little boards a shot, they were cheaper for Bluetooth/WiFi combo, and I don't need all the bells and whistles of a full ESP32.

I have my firmware all debugged and working, it's been stable for a few months now. All it does is read a temperature from an Inkbird Bluetooth temperature sensor and log that info into a spreadsheet online for me via WiFi.

Up until this point I had the board connected via usb cable to my PC. Well I got a new PC and wanted to save a usb port so I moved it to a usb cable with an Apple AC wall adapter (5V 500mA). The board now never powers on.

Does anyone know what's happening here? It seems to not like booting unless it has a serial connection with the PC??? It doesn't like to power on if the PC is off either even though the usb port has power still.

I thought maybe this weird usb C port doesn't like 5V. So, I got it 3.3V via a breadboard power adapter rig. Nothing...

  • Does anyone know what's happening here? ... no ... you are the only one in a position to know ... we can guess that your code has a bug ... possibly something to do with waiting for a serial port connection
    – jsotola
    Feb 24, 2023 at 17:55
  • Well there you have it. That's exactly what was happening! Thank you! Feb 24, 2023 at 22:49
  • next time, if you have a question, please include all info ... do not withhold important things like the code
    – jsotola
    Feb 25, 2023 at 1:21

1 Answer 1


Your program could be busy, waiting for the com port to open.

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