FDCAN availability on STM32H747I-DISCO board

[prashanth1]

Moved from this thread.

Thanks for the previous response — it helped me understand the configuration better.

Now I have a follow-up doubt:

In STM32CubeIDE, I can see multiple pin options for FDCAN1_RX and FDCAN1_TX in the pinout view. However, when I checked the STM32H747I-DISCO board, those selected pins (e.g., PB8, PB9, etc.) don’t seem to be accessible via any header pins or exposed GPIOs on the board.

So my question is:

Are there any accessible pins on the STM32H747I-DISCO board that I can actually use to connect FDCAN1 to an external CAN transceiver like the TJA1051T/3?

Would appreciate any guidance — especially if there's a known method to access these signals (e.g., via Arduino headers, PMOD, or solder points).

Thanks!

[mƎALLEm · Accepted solution]

Hello,

The only solution for FDCAN1 usage on this board is to use STMOD+ connector where PB8 (FDCAN1_Rx) and PB9 (FDCAN1_Tx) are available on pins 19 and 20. From the board's user manual UM2411:

From the board's schematic:

Unfortunately, FDCAN2 is not an alternative as all the pins are already used externally by some hardware.

Hope that answers your question.

[Andrew Neil]

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@mƎALLEm wrote:

Unfortunately, FDCAN2 is not an alternative as all the pins are already used externally by some hardware.

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@prashanth1 this is always the trouble on dev boards with many bundled "extras";  particularly displays - which can be very hungry on pins!

For better access to the chip itself, maybe look at a Nucleo board - they are far simpler, so don't use-up so many pins...

[mƎALLEm]

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@Andrew Neil wrote:

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 particularly displays - which can be very hungry on pins!

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Particularly for this board, it's mostly the external memory over FMC (SDRAM) which is consuming the IOs the most. The display in this board is driven over DSI interface (only 8-9 pins):

[prashanth1]

Hi @mƎALLEm ,

I just wanted to thank you for your detailed response to my question regarding FDCAN1 on the STM32H747I-DISCO board. Your advice was incredibly helpful, and I was able to successfully configure FDCAN1, and it is now fully working!

I really appreciate the time you took to assist me.

Thanks again!

Best regards,
@prashanth1

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Feel free to personalize it further if needed!

[Ozone]

As the name suggests, the discover boards are good for "discovery" and playing around.
They are more of a showcase.

For real-world applications, they are mostly unusable.
Better get a Nucleo board for that purpose.
Nucleo boards contain only absolutely necessary components, and route all other pins to easily accessible headers.
And besides, by omitting expensive components like displays they are reasonably cheap.