SW-CAN 33.3K & 500K Question

Hello, I am inquiring as to if the AutoPi can communicate on both SWCAN 33.3kbps and the 500k bus on GM vehicles? I know that I have to send a wakeup command on one bus and then send the desired command on the second bus once its awake.


Hi @efilive

Yes both prototols should be supported by the AutoPi.

In our obd.send command there is an option to add the protocol as a parameter, this means that you could potentially setup some code to do the following:

obd.send 433#4455667788 protocol=4
obd.send 111#4455667788 protocol=9

This would allow you to do what you want.


Hello all,

Did you find the way to wake up ECUs in the GM cars? Autopi can wake up triggered by sms, but the CAN network will be offline after some time you left off the car. The only option I know at that moment to wake up all ECUs in the car Is by using the car remote. Anyhow, before sending wake up CAN messages, we have to wake up ECUs. ECUs needs to be wake for receiving CAN message. If I’m not wrong, in sleep mode of a CAN network, the voltage is 2.5V for each wire (CAN HIGH and CAN LOW) and each CAN node in the network will wake up when the voltage is modified (ex: 1,5V for CAN LOW and 3,5V for CAN HIGH. It’s just an example presumption of the voltage values). In that case, it’s not a good option for me to use an electronic workout to “physically Change the voltage level”.

Any hint on how to find out the wakeup solution of the CAN network it will be helpful. The voltage for the CAN wires should be controlled first by a Master node, which should be the ECU responsible for the reception of the keyfob information…then how can I wake up this ECU first? :smiley:

I think this is not only about GM, but also about any ECU wake up solution in a CAN network.

I’m not working with an AutiPi module at that moment talk because I don’t have one. I’m here because I want to buy one in the feature, so I hope to work with all of you on the same platform soon. I’m using linux and some USB to CAN analyzer for logging/sniffing and if there will be some ideas in here on what to test, I can help also because I’m interested in also!