FDCAN 1 and FDCAN 2

[Jad]

Good morning, I am currently working on the nuclei H755 ziq. it says on the data sheet and on stm32ide that it has two FDCANS. however, I have only found in the schematics one tx and one rx port. how do I know if they are connected to FDCAN 1 or FDCAN 2? I have found on stm32 side that it was for fdcan 1 and the fdcan 2 on  PD15 and PD20. however, it is ,not written on the schematics. is it an error? 

[SofLit · Accepted solution]

Hello @Jad ,

PD0 and PD1 is for FDCAN1.

You can use FDCAN2 on this Nucleo board through PB12 for FDCAN_RX and PB13/PB6 for FDCAN_RX. But for PB13 you need to remove the jumper JP6 . 

PS there is no PD15 has no FDCAN function, and PD20 does not exist.

You need to refer to the product datasheet and what are the alternate functions available for the IOs and what are the possibilities available for you on this package.

Hope I answered your question

[Jad]

thanks for the response, it was clear. but I am wondering how I could have known that since it is not written in the data sheet.

[SofLit]

Which datasheet? I've already said that the information is in the product datasheet.

The board connectors just offer a possibility to use a function or another it don't force you to use it as it is. For example, for FDCAN1 there are other possibilities on PB8 and PB9 nothing prevents you to use them except if there is a hardwired connection on them.

[Jad]

 i am sorry for the missunderstandig, it is the first time I think about using the jumpers. I this information on the JP6, this does mean so that if I want to use them I have to remove JP6? and does the removal of the jumper has other consequences?

[SofLit]

Removing JP6 disconnects the RMII_TXD1 pin (Ethernet function) from PB13 and therefore from FDCAN pin. This prevents any disturbance on FDCAN pin.

If in next time you will use ETH, you need to fit JP6 back.

Hope it's clear now.

[Jad]

yes, thank you very much.