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Kititas
Associate
Jun 17, 2025 3:39 AM UTC
Solved

Can't find pins to connect to FDCAN peripheral on STM32U5G9J-DK2

I try to create vehicle GUI on STM32U5G9J-DK2, but I can't find CAN pin to send data out from board to another node in CAN bus.

Kititas_0-1750131314659.png

 

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mƎALLEm
mƎALLEmBest answer
ST Technical Moderator
Jun 17, 2025 10:41 AM UTC

Hello,

Doing the exercise with CubeMx, these are the only available pins for that product package:

mALLEm_1-1750156698103.png

Unfortunately there is no possibility to use FDCAN in that board as some CAN pins are connected to some external hardware while other usable pins (like PD0 and PD1 as LCD inputs) are not exposed on CN1 connector.

 

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4 replies

Ozone
Ozone
Principal
Jun 17, 2025 5:45 AM UTC

> I try to create vehicle GUI on STM32U5G9J-DK2, but I can't find CAN pin to send data out from board to another node in CAN bus.

You mean, none of the connector pins is labelled "CAN" ?

You need the consult the datasheet of the STM32U5G9J, and check what GPIOs can be configured as CAN. Crosscheck with the schematics of your board.
And most probably make and attach the CAN transceiver circuitry yourself.

KititasAuthor
Associate
Jun 17, 2025 6:09 AM UTC

There are CAN pins, but they are used for LCD screen. There is one FDCAN rx pin left for use, but I can't find available CAN tx pin. I just want to ask if there is a way I can connect CAN pin out from this board, in case I'm missing something.

Ozone
Ozone
Principal
Jun 17, 2025 6:49 AM UTC

I don't know this specific one, but made similiar experiences with other Discovery board.

If you don't use the LCD display and there is no interfering circuitry connected, you might be able to use these pins.

But a lot of ST's Discovery boards are cluttered with features and peripherals "undesirable" for many application. Especially boards with displays or external memory make most of the available GPIOs unusable for other applications.
The Nucleo board series is much better in this regard, only the bare minimum of peripherals comes onboard.

If CAN is unusable with your board, you still have the option of an external standalone CAN controller, like e.g. the MCP2515 (with SPI interface).

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