ESP32 Forum

Hello,

I've been able to read the MS-CAN (95kbps) in my GM car using the next hardware combinations powered from a laptop's USB port:

-ESP32 devkitc V4 module + SN65HVD230 transceiver

-Arduino Uno + CAN board with controller MCP2515 (+TJA1050 transceiver)

I was also successful reading the LS-CAN (33.3kbps) with the Arduino Uno, by connecting CAN_L to ground and CAN_H to the single-wire bus.

However, when using the ESP32, no data is received, and what's worse, when CAN_L is connected to ground, the speedometer and headunit display (GID screen) get turned off! Why? Edit: I found out disconnecting the TX connection between uC and transceiver stops the problem.

I'm using Sandeep Mistry's Arduino-CAN library, but since it's unmaintained, I have mister0wl's fork which has support for the newer ESP32 chips, that allow configuring lower baud rates (<50kbps)

I was thinking about using the MCP2515 + SN65HVD230, but I'm not sure there are libraries out there that accept this combo along with low baud rates.

Has anyone been lucky doing this with the ESP32?

EDIT: I would like to use the TWAI driver and no 3rd party libraries. Can somebody help me setup the driver for this custom baudrate?

Thanks

Perhaps I'm oversimplifying, but isn't it "just" augmenting with another timing configuration? Valid values for brp, tseg_1, test_2, sjw, and triple_sampling for the bitrates you're after should be documented somewhere.

I have also accessed the GM low speed bus.. .33.3kbps? I believe I did this with same library as you on ESP32, however my other main project uses the 500kbps CAN bus and I am having big problems finding ESP32 Devkit V1's that work... the older ones I have work fine but the newer ones.. only 1 out of 9 work on GM CAN.

They will work if I wire them together and send messages, but only 1 works on the GM CAN network. Wonder if your problem is related. All of my other ESP32 versions work fine *Devkit v4, NodeMCU, etc).

I wonder whether it's possible at all to use the standard CAN controller together with a single-wire CAN transceiver…

DrMickeyLauer wrote: ↑

Tue Nov 07, 2023 9:33 am

I wonder whether it's possible at all to use the standard CAN controller together with a single-wire CAN transceiver…

Not sure how to do that.. the ESP32 uses RX and TX to the external CAN transceiver.

I guess this is no problem. I have checked data sheets of some single wire CAN transceivers and it looks like it's only the physical layer that's different. From the controller side, it's still RXD/TXD.