I tried the example "FDCAN_Com_polling" on STM32H743I-EVAL, it worked like it should be.
Then I separated the example code into TX part and RX part, made one of my STM32H743I-EVAL board as TX and another as RX, but the RX did not work, it never received anything and the HAL_FDCAN_GetRxFifoFillLevel always get 0.
All jumpers and SBs on the EVAL board were removed or connected following the instructions on the EVAL's reference manual, and I checked the waveform on the RX side and it seems correct.
The filter setting should be good as well because the TX side can receive its own loop back frame by using the same filter settings.
Any hint what went wrong or which part should check next?
Thanks in advance.