Thanks @felmue, I have now got the card powered by following your observations : connecting 5v to VIN, GND to GND, TX to RXD, RX to TXD I don't need to trigger PWK to get the modem operational. The modem don't connect to the network, but that's another problem..

@funkyfab said in USB driver for Raspberry Pi: I'll answer myself ;-) I copied the /lib/udev/rules.d/69-libmtp.rules to /etc/udev/rules.d, added the line ATTR{idVendor}=="0403", ATTR{idProduct}=="6001", GOTO="libmtp_rules_end" That prevents the M5 devices to be recognized as MTP devices. Then they're recognized as Serial ports, and Arduino IDE can access them. So we don't need the driver, just a change in udev configuration. Oh cool, thats for working out how to do this. I can continue my plans of adding an RPI to my project bench to programme the M5Stacks and Sticks. Thanks you.