can_demo.py

#!/usr/bin/env python
"""
General CAN functions using Kvaser canlib
"""
from __future__ import print_function

import logging
from sys import exit

# kvaser canlib
from canlib import *


def setup(port_id, bitrate=canBITRATE_250K):
    """Setup kvaser CAN given port_id which may be device channel or serial number"""
    cl = canlib()
    channels = cl.getNumberOfChannels()

    logging.info("Kvaser canlib version: %s, %d channels available" %
                 (cl.getVersion(), channels))

    chans = {}
    for ch in range(0, channels):
        try:
            info = (ch,
                    int(cl.getChannelData_Serial(ch)),
                    cl.getChannelData_Name(ch),
                    cl.getChannelData_EAN(ch))

            chans[ch] = info  # key on channel number
            if info[1] >= channels:
                chans[info[1]] = info  # key on serial number
        except (canError) as ex:
            print(ex)

    try:
        ch = chans[port_id][0]
    except KeyError:
        print('A valid port number is required for --port option:')
        for k in chans.items():
            print('%d: %s' % k)
        print()
        exit()

    chan = cl.openChannel(ch, canOPEN_ACCEPT_VIRTUAL | canOPEN_REQUIRE_EXTENDED)
    chan.ioCtl_set_timer_scale(100)  # microseconds per tick
    chan.timer_scale = 100
    chan.setBusOutputControl(canDRIVER_NORMAL)
    chan.setBusParams(bitrate)
    chan.busOn()

    return chan, cl


error_flags = (canMSG_ERROR_FRAME | canMSG_NERR |
               canMSGERR_HW_OVERRUN | canMSGERR_SW_OVERRUN)


def flags_str(flags):
    fl = []
    if flags & canMSG_RTR: # 	1	Message is a remote request
        fl.append('RTR|')
    if flags & canMSG_STD:	#2	Message has a standard (11-bit) identifier
        fl.append('STD')
    if flags & canMSG_EXT:	#4	Message has a extended (29-bit) identifier
        fl.append('EXT')
    if flags & canMSG_WAKEUP:	#8	Message is a WAKEUP message (SWC hardware.)
        fl.append('WAKE')
    if flags & canMSG_ERROR_FRAME:	#32	Message represents an error frame.
        fl.append('ERR')

#The following flags can be returned from canRead() et al, but cannot be passed to canWrite():
    if flags & canMSG_NERR:  # 16	NERR was active during the message (TJA1054 etc. hardware. See Note 4 below.)/tr>
        fl.append('NERR')
    if flags & canMSG_TXACK	:  # 64	Message is a TX ACK (meaning that the message was really sent)/tr>
        fl.append('TXACK')
    if flags & canMSG_TXRQ:	 # 128	Message is a TX REQ (meaning that the message was transferred to the CAN controller)/tr>
        fl.append('TXRQ')
    if flags & canMSGERR_HW_OVERRUN:	 # 512	Hardware buffer overrun.
        fl.append('HWOVR')
    if flags & canMSGERR_SW_OVERRUN:	 # 1024	Software buffer overrun.
        fl.append('SWOVR')

    return '|'.join(fl)


def add_options(p):
    '''Add CAN related options to an optparse instance'''
    p.add_option('-b', '--bus', type='int', default=1,
                 help='CAN bus index 1 or 2. Default=%default')
    p.add_option('-p', '--port', type='int', default=0,
                 help='CAN channel #, typically 0 or 1, or device serial')
    p.add_option('-F', '--fake', action='store_true',
        help='Send packets direct to localhost MQTT broker instead of serial port')


if __name__ == '__main__':
    from collections import defaultdict
    from optparse import OptionParser
    import random
    import time
    
    def parse_options():
        p = OptionParser()

        add_options(p)
        p.add_option('-l', '--loglevel', type='int', default=3,
                     help='Logging level. Default=%default')
        opts, args = p.parse_args()

        level = {1: logging.ERROR, 2: logging.WARNING, 3: logging.INFO,
                 4: logging.DEBUG}.get(opts.loglevel, logging.DEBUG)
        opts.loglevel = level

        return opts, args

    
    opts, args = parse_options()
    logging.basicConfig(level=opts.loglevel)

    busname = 'CAN-%d' % opts.bus

    ch, lib = setup(opts.port)

    num_messages = 100
    if args[0].startswith('w'):  # 
        max_std = 2047
        logging.info('Generating %d packets to %s (port#%d)' % (num_messages, ch.getChannelData_Name(), opts.port))
        sent = []
        for i in range(num_messages):
            msg = []
            for m in range(random.randint(1, 8)):
                msg.append(random.randint(0, 255))
            id = random.randint(0, max_std)
            sent.append(id)
            print(id, msg)
            ch.write(id, msg)   
        print(sent)
    else:
        msgs_received = defaultdict(list)
        logging.info('Receiving %d packets from %s (port#%d)' % (num_messages, ch.getChannelData_Name(), opts.port))
        for i in range(num_messages):
            try:
                msg = ch.read(5000)  # Ohhh, timeout seems to be in milliseconds, should be float seconds!
            except canNoMsg as e:
                logging.warning('No messages received for 5 seconds')
                continue
            except Exception as e:
                logging.error(str(e))
                continue
                    
            # print("%d rx id: %08X msg: %s" % (i, id, [x for x in msg]))
            msgs_received[msg[0]].append(msg)

        ml = msgs_received.items()
        ml.sort()
        for k, v in ml:
            print('Rx ID: %08X' % k)
            for msg in v:
                print("dlc: %08X msg: %s" % (msg[2], [x for x in msg[1]]))