Question

Is it possible to achieve full-duplex communication using PySerial? Specifically, would it be possible to monitor the port continuously for input and write whenever needed? I imagine it should be possible using threads (and serial interfaces are full duplex no?). If not, what would be the best approach to monitoring a serial port when not transmitting? A timeout?

Edit: Here’s my attempt at it. This code is targeting TI’s CC2540 Bluetooth LE chip. On sending the GATT init message I expect a reply (detailing the operating parameters of the chip)…I’m getting nothing though

import serial
import threading
from time import sleep

serial_port = serial.Serial()

GAP_DeviceInit  = \
                "\x01\x00\xfe\x26\x08\x03\x00\x00\x00\x00\x00\x00\x00\x00\
                \x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
                \x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00"

def read():
    while True:
        data = serial_port.read(9999);
        if len(data) > 0:
            print 'Got:', data

        sleep(0.5)
        print 'not blocked'

def main():
    serial_port.baudrate = 57600
    serial_port.port = '/dev/ttyACM0'
    serial_port.timeout = 0
    if serial_port.isOpen(): serial_port.close()
    serial_port.open()
    t1 = threading.Thread(target=read, args=())
    while True:
        try:
            command = raw_input('Enter a command to send to the Keyfob: \n\t')
            if (command == "1"):
                serial_port.write(message)
        except KeyboardInterrupt:
            break
    serial_port.close()

Answer 1

Yes serial port hardware is full duplex. Yes, you can use threads to do Rx and Tx at the same time. Alternatively, you can use a single thread loop that does reads with a short timeout and alternates between reading and writing.