spawn_serial.py

import threading
import serial
import queue
import time

# make thread-safe queue for data logging/writing
global_dataMsgQ = queue.Queue()

# make a thread-safe queue to inform different threads when it's time to stop
global_stopQ = queue.Queue()


def serial_read_function(serial_port_obj, dataMsgQ, stopQ):
    while True:
        # check if we should stop
        try:
            stopQ.get_nowait()
            serial_port_obj.close()
            break
        except queue.Empty:
            pass

        # read serial port
        aline = serial_port_obj.readline()

        # if there's no data before the serial object timeout,
        # then it's reasonable for aline to sometimes be empty
        if len(aline) > 0:
            dataMsgQ.put((serial_port_obj.name, aline))
# end serial_read_function


def spawn_serial_thread(port_name='/dev/ttyUSB0', baud_rate=151200,
                        timeout=0.1):
    # make serial port
    serial_port_obj = serial.Serial(port_name, baud_rate, timeout=timeout)

    thread_obj = threading.Thread(
        target=serial_read_function,
        args=(serial_port_obj, global_dataMsgQ, global_stopQ)
    )
    thread_obj.start()
    return (serial_port_obj, thread_obj)
# end spawn_serial_thread


def data_writer_function(fpath, dataMsgQ, stopQ):
    with open(fpath, "w") as f:
        while True:
            # check if we should stop
            try:
                stopQ.get_nowait()
                break
            except queue.Empty:
                pass

            # check for messages to write
            try:
                ser_name, data = dataMsgQ.get_nowait()
                # you'll want to fix this, I have no idea what the data format is or should be
                f.write(data)
            except queue.Empty:
                pass
        # end while(True)
    # end with open(fpath)
# end data_writer_function


def spawn_data_writer_thread(fpath):
    thread_obj = threading.Thread(
        target=data_writer_function,
        args=(fpath, global_dataMsgQ, global_stopQ)
    )
    thread_obj.start()
    return thread_obj
# end spawn_data_writer_thread


def main():
    # make two serial ports and threads
    s1, t1 = spawn_serial_thread('COM1', 115200, 0.1)
    s2, t2 = spawn_serial_thread('COM2', 115200, 0.1)

    # make data writing thread
    data_writer_thread = spawn_data_writer_thread('log_fpath_goes_here.csv')

    # wait 10 seconds
    time.sleep(10.0)

    # close up shop
    # put a bunch of things on the queue to make sure all threads stop
    for ix in range(10):
        global_stopQ.put(None)

    # wait for all threads to cleanly exit
    thread_list = [t1, t2, data_writer_thread]
    while(any([t.isAlive() for t in thread_list])):
        time.sleep(0.05)
# end main