Pi Pico: read/write data over usb cable

Question

How can I read/write data to my Raspberry Pi Pico using Python/MicroPython over the USB connection?

(I have seen a lot of question across the internet on this with few answers, so I thought I share it here to make it easy to find)

Asked By: basil_man

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Source

Answer 1

Directions:

Use Thonney to put micropython code on to the Pi Pico. Save it as ‘main.py’.
Unplug Pi Pico USB.
Plug Pi Pico USB back in. (DON’T hold do the boot button)
Run the PC Python code to send and receive data between the PC and Pi Pico.

Code for the Pi Pico:

read data from sys.stdin

write data using print

poll is used to check if data is in the buffer

import select
import sys
import time

# Set up the poll object
poll_obj = select.poll()
poll_obj.register(sys.stdin, select.POLLIN)

# Loop indefinitely
while True:
    # Wait for input on stdin
    poll_results = poll_obj.poll(1) # the '1' is how long it will wait for message before looping again (in microseconds)
    if poll_results:
        # Read the data from stdin (read data coming from PC)
        data = sys.stdin.readline().strip()
        # Write the data to the input file 
        sys.stdout.write("received data: " + data + "r")
    else:
        # do something if no message received (like feed a watchdog timer)
        continue

Code for PC:

import serial


def main():
    s = serial.Serial(port="COM3", parity=serial.PARITY_EVEN, stopbits=serial.STOPBITS_ONE, timeout=1)
    s.flush()

    s.write("datar".encode())
    mes = s.read_until().strip()
    print(mes.decode())


if __name__ == "__main__":
    main()

‘serial’ is PySerial

Answered By: basil_man

Pi Pico: read/write data over usb cable

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