How to set FDCAN peripheral in STM32H7 NUCLEO Board

[Vergnani_ElEn]

Hi,

I’m trying to configure the FDCAN peripheral on a NUCLEO-STM32H72ZG board, but even though it works perfectly in loopback mode, it doesn’t work when I switch to normal mode. Even in external loopback, when I check with the oscilloscope I don’t see any activity on the TX pin (no signal transitions).

The same issue occurs on this board also with GPIOs.

I tried the same setup on a NUCLEO-STM32F303RE board (using CAN instead of FDCAN), and everything works perfectly there.

[mƎALLEm · Accepted solution]

Hello,

You said:

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@Vergnani_ElEn wrote:

Hi,

I’m trying to configure the FDCAN peripheral on a NUCLEO-STM32H72ZG board, but even though it works perfectly in loopback mode.... Even in external loopback, when I check with the oscilloscope I don’t see any activity on the TX pin

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Do you mean that it does work in Internal Loopback mode but it doesn't in External Loopback?

If it works in Internal loopback it should work in External Loopback mode.

For Normal mode you need to establish a complete CAN bus where you are using a transceiver to connect the MCU to the bus and at at least another CAN node that should see your node on that bus to acknowledge the frames sent from your CAN node. This is the minimum hardware requirement to establish a CAN bus:

CAN is not UART or SPI to monitor the traffic in "open bus" mode.

Related knowledge base articles:

STM32 FDCAN running at 8 Mb/s on NUCLEO boards

How to use FDCAN to create a simple communication with a basic filter

Using CAN (bxCAN) in Normal mode with STM32 microcontrollers (Part 1)

Using CAN (bxCAN) in Normal mode with STM32 microcontrollers (Part 2)