STM32H743: What is the purpose of pins FDCANn_TXFD/RXFD

[GS1]

Posted on March 01, 2018 at 14:39

We are currently setting up a project using STM32H743 and need to implement CAN / CAN-FD. When activating FDCAN1 or 2 in Cube as Mode 'FD', two additional checkboxes can be activated: Enable_FDCAN_TXFD and Enable_FDCAN_RXFD. When activating these, two additional RX/TX Pins are activated on the chip. What is the purpose of these Pins? Do we need to enable them to have CAN-FD work properly? I could not find any declaration of this. 

Thank you for any help.

Gabriele

[Imen.D]

Posted on April 11, 2018 at 18:23

Hello

Suchy.Gabriele

,

Each FDCAN instance has 4 signals:

CANn_RXFD/ CANn_TXFD are both outputs pins and they are used only for debug to show that the peripheral is in FDCAN mode.

CANn_RX/ CANn_TX are used for CAN communicationas FDCAN Pins or classical CAN.

Best Regards,

Imen

[Yan Rosh]

Posted on May 24, 2018 at 09:21

Hello,

Sorry to reopen an old thready, but I just wanted to make sure what do you meant by debug outputs...

We can use these pins to monitor the communication with a scope without probing the 'real' TX/RX lines?

Are there any other functionality these pins provide?

Can we use CANFD without these pins enabled?

Thanks in advance,

Yan

[Imen.D]

Posted on May 24, 2018 at 09:50

Hello

yan.rosh

,

CANn_RXFD/ CANn_TXFD are used only for debug and their usage is optional.

We can use CANFD without these pins enabled.

With Regards,

Imen

[Stefan Meier]

Posted on May 31, 2018 at 12:37

This should really be mentioned in some documentation of the MCU.