How to upload files to MicroPython over USB/serial

In this post we will investigate how to connect to a wireless network on boot

First, install ampy - a tool to modify the MicroPython filesystem over a serial connection.

sudo pip3 install adafruit-ampy

Now prepare your script - we’ll use main.py in this example.

Upload the file to the board:

ampy -p /dev/ttyUSB* put main.py

This only takes about 2-4 seconds. In case ampy is still running after 10 seconds, you might need to

• Stop ampy (Ctrl+C), reset the board using the RESET button and retry the command
• Stop ampy (Ctrl+C). Detach USB and ensure the board is powered off (and not powered externally). Re-Attach USB and retry the command.
• In case that doesn’t help, try re-flashing your board with the most recent version of MicroPython. See How to flash MicroPython to your ESP32 board in 30 seconds. This will also clear the internal filesystem and hence remove any file that might cause failure to boot properly.