Hey everyone!
I've been dealing with an issue for a while involving two CAN modules: a mini MCP2515 module and a regular CAN BUS Shield (both based on the MCP2515).
I’m using this library:
I’ve been testing the "send" and "receive" examples — one on an Arduino Nano with the MCP2515 module, and the other on an Arduino UNO with the CAN BUS Shield.
When I send commands from an ELM327 to either module (both using the same library and connected to the same CAN wiring), they both seem to receive data from the ELM327 just fine and print it over Serial. But when I try to have one board run "send" and the other "receive", they don’t communicate with each other at all.
What’s weird is that when I use two regular CAN BUS Shields (with the same library), they do communicate perfectly. But if I swap one for the MCP2515 module, neither of them receives anything!
I’ve tried messing with the 120Ω termination resistors — adding, removing, swapping — but still no luck.
As for the ELM327, I use it with my car, and for some ECUs to respond, I have to remove its built-in 120Ω resistor (R121). Still, communication works even with only one termination resistor on either module and ELM327(both the Shield and the MCP2515 have removable resistors for testing).
I also tried switching setups: uploading "send" on the Nano + MCP2515 and "receive" on the UNO + CAN Shield, and vice versa. No results either way.
So my question is: why is this happening?
Any ideas would be really appreciated!
Thanks in advance,
Julio