openinverter forum

Hi
I just received the package of the mini inverter and ESP32 CAN interface.
I connected CAN H to CAN H and CAN L to CAN L and powered 12v on the boards
Nothing else connected.
I am receiving the message " Communication problem between ESP and STM "
I tried changing the speed to 250 and back to 500 . Nothing
Should I connect a resistor on the boards ? The resistance on the can circuit is 37kΩ and voltage when powered 0.2V DC
I didnt downloaded anything on the boards . I used them immediatelly out of the box
Do I miss something on the procedure ?

Yes you need termination resistors on the CAN network each end needs 120ohm, so total 60ohm when nothing is powered on.

The ESP module has a solder jumper for termination

What johu said above was perhaps obvious to most, but it was something I didn’t know when starting out - you can only measure for the appropriate resistance in CAN lines when they are powered down. And the correct resistance is 60ohms - that means you have the appropriate number of 120 ohm resistors on the line.