mapid/fifo_bridge.py

#!/usr/bin/env python3

import os
import sys
import time
import mapid
from serial.serialutil import SerialException


mapid.load_dotenv()
FIFO = os.environ.get("FIFO")


def main():
	global FIFO
	if len(sys.argv) == 2:
		FIFO = sys.argv[1]

	# Write PID
	FIFO_BRIDGE_PID_FILE = os.environ.get("FIFO_BRIDGE_PID_FILE")
	f = open(FIFO_BRIDGE_PID_FILE, "w")
	f.write(os.getpid())
	f.close()
	del f

	# Create MAPIDCP object to communicate with the Arduino
	m = mapid.MAPIDCP()

	# Create FIFO
	os.mkfifo(FIFO)
	time.sleep(0.2)
	print("Created FIFO " + FIFO, file=sys.stderr)

	f = open(FIFO, "r")
	print("Opened FIFO for reading", file=sys.stderr)

	# Show greeting on screen
	m.cls()
	m.line(1)
	m.echo("fifo_bridge.py")
	m.line(2)
	m.echo(FIFO)

	# Main loop: read commands from FIFO and execute it
	keep_going = True
	while keep_going:
		try:
			line = f.readline().strip("\n")
			m._cmd(line)
		except KeyboardInterrupt:
			keep_going = False
			print()
		except SerialException:
			keep_going = False
			print("Caught a SerialException. Exiting now...", file=sys.stderr)

	# Remove FIFO and PID files
	os.remove(FIFO)
	os.remove(FIFO_BRIDGE_PID_FILE)
	print("Removed FIFO.", file=sys.stderr)


if __name__ == "__main__":
	main()