mqtt_can.py

"""
A CAN bus gateway over MQTT
"""
import paho.mqtt.client
import logging
from dotenv import load_dotenv
import os

load_dotenv()

log = logging.getLogger(__name__)
log.setLevel(logging.INFO)

class CanMsg:
    def __init__(self, pkid, data, rtr=0):
        self.rtr = rtr
        self.pkid = pkid
        self.data = data

def on_connect(client, userdata, flags, rc, properties=None):
    log.info("on_connect rc %d", rc);
    client.subscribe("/heizung/burner/can/raw/recv/")

def on_message(client, userdata, msg):
    try:
        m = msg.payload.decode().split(";")
        log.debug("on_message %s : %s", msg.topic, str(m))
        canmsg = CanMsg(int(m[1], base=16), bytes.fromhex(m[2].strip("\x00")), int(m[0]))
        callback(canmsg)
    except Exception as E:
        log.exception("Exception on_message %s : %s", msg.topic, msg.payload)

def on_disconnect(client, userdata, rc):
    log.info("on_disconnect rc %d", rc);

def send_can(pkid, data, rtr=0):
    mqt = "/heizung/burner/can/raw/send"
    dstr = " ".join(["{0:x}".format(d) for d in data])
    mqm = "{rtr:x};{i:x};{d:s}".format(rtr=rtr, i=pkid, d=dstr)
    return client.publish(mqt, mqm, 1).wait_for_publish()

callback = None

client = paho.mqtt.client.Client(client_id="logamatic_mqtt_can_interface")
client.on_connect = on_connect
client.on_message = on_message
client.on_disconnect = on_disconnect

def start(deliver_callback):
    log.info("Start MQTT CAN receiver")
    global callback
    callback = deliver_callback
    rc = client.connect(os.getenv('MQTT_READ_HOST', 'localhost'))
    log.info("client.connect %d", rc)
    client.loop_start()

def stop():
    log.info("Stop MQTT CAN receiver")
    client.loop_stop()

def test_callback(msg):
    log.info("test_callback")
    log.info("id %d data %s", msg.pkid, msg.data.hex())

if __name__ == "__main__":
    logging.basicConfig()
    start(test_callback)