Hello @sujeong and welcome to the ST community,
FDCAN pins are available as the following on the board:
FDCAN1_Rx / PD0 available on CN15 pin 33
FDCAN1_Tx / PA12 available on ARDUINO® Uno V3 (CN4) pin 4 or PH2 available on CN3 pin 38.
FDCAN3_Rx / PE12 on CN15 pin 1
FDCAN3_Tx / PE11 on CN15 pin 23
FDCAN2_Rx is overlapping with the serial wire debug pin SWO pin.
How to check that?: need to refer to the datasheet of the product, find the FDCAN pins you need to use and finally check on wihch board that pin is available by referring to the user manual of the board: UM3417 especially the sections: 8.5 ARDUINO® Uno V3 V3 connectors (CN4, CN5, CN13, CN14) and 8.6 ST morpho connectors (CN2, CN3, CN15, CN16)
You need to add a CAN or FDCAN transceiver (depending on the mode) externally to that board to connect it to a CAN bus.
Hope that helps.
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