Flask server to receive commands via /switch endpoint and send them via USB to CircuitPlayground Express

command_sender.py

import serial
from flask import Flask, Response

# /dev/ttyACM0 is the USB interface to CPX on my Pi. It might be different for you,
# there are many resources on the web to help you find the correct interface.
SERIAL_PATH = '/dev/ttyACM0'

BAUDRATE = 115200
TIMEOUT = 0.01
SER = serial.Serial(SERIAL_PATH, baudrate=BAUDRATE, timeout=TIMEOUT)

app = Flask(__name__)

@app.route('/switch/<command>')
def switch(command):
    try:
        send_serial_cmd(command)
        return Response(status=200)
    except Exception:
        return Response(status=500)


def send_serial_cmd(command):
    out = bytes(command, 'utf-8') + b'\n'
    SER.write(out)
    SER.flush()


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000)