Can I use the xmodem protocol with PySerial?

Question

I have a working connection with my serial device via PySerial, but I also want to transfer files via the xmodem protocol as part of my program.

Which would be the most platform-neutral way to do this? Worst case, I could close() my serial.Serial object in Python and use subprocess to call upon /usr/bin/sb, but that seems inelegant.

I'm currently on Ubuntu 9.10 and am using a USB-TTY adapter.

Any ideas?

Answer 1

There is xmodem module on PyPi. It takes two functions in constructor for reading and writing data, implement them to work with your opened serial port. Below is simple sample of its usage:

import serial
try:
    from cStringIO import StringIO
except:
    from StringIO import StringIO
from xmodem import XMODEM, CRC
from time import sleep

def readUntil(char = None):
    def serialPortReader():
        while True:
            tmp = port.read(1)
            if not tmp or (char and char == tmp):
                break
            yield tmp
    return ''.join(serialPortReader())

def getc(size, timeout=1):
    return port.read(size)

def putc(data, timeout=1):
    port.write(data)
    sleep(0.001) # give device time to send ACK


port = serial.Serial(port='COM5',parity=serial.PARITY_NONE,bytesize=serial.EIGHTBITS,stopbits=serial.STOPBITS_ONE,timeout=0,xonxoff=0,rtscts=0,dsrdtr=0,baudrate=115200)
port.write("command that loads data via xmodem\r\n")
sleep(0.02) # give device time to handle command
readUntil(CRC)
buffer = StringIO('data to send')
XMODEM(getc, putc).send(buffer, quiet = 1)
buffer.close()
readUntil()