Troubleshooting communication with MC824H

[beestree]

Hi, I'm having trouble getting this to work with my MC824H.

My setup is as follows: I have an ESP8266 (Wemos D1 mini) with a Waveshare CAN transceiver connected to the TX/RX pins and the 3V3 and GND pins of the ESP. I've connected the CANH and CANL directly to the MC824H with an RJ11 connector. The ESP is powered by its usb port (this might be problematic, as they don't have common ground this way?)

I got this working, but now I can't get it to connect. The logs show that I get the exact messages I send reflected back.

My question is: Is this the correct way to set this up? Do I need a resistor to prevent reflections? And if so, why did this work previously?

[xCapeITA]

Hi @beestree have you got the right commands for mc824h?
I am seeking them but cannot find.
Plus I don't have any feedback from unit (but I can send commands). Do you connect it with resistor? Thanks

[ozitvogel]

It is working perfectly with the MC824H by connecting directly to the IBT4N 5*2 connector in UART TTL mode (just remove the the RJ11 to IBT4N adapter and connect with a DC/DC 30V -> 5V converter and a logic level shifter 3V3 <-> 5V. I did not test the RJ11 CAN approach as this probably requires an extra CAN/UART conversion component. All that said are you sure you did not invert CANH/CANL (@beestree) ? @xCapeITA same remark. With an UART setup you will obviously connect ESP’s TX to IBT4N’s RX and ESP’s RX to IBT4N’s TX…