Difference between nominal and data bit time FDCAN parameters

CTabo.1 · ‎2024-03-26

Hello,
I am developing a CAN bus application.

I am new to the FDCAN peripheral and I haven't understood the difference between nominal bit time parameters and data bit time parameters.

Which of these two groups of parameters should I configure to obtain the desired baud-rate and sample point?

Regards,
Carlo

SofLit · ‎2024-03-26

It depends on what mode you configured for your FDCAN peripheral.

Did you configure it in Classical mode? i.e. CAN2.0 of CANFD?

For Classical CAN, only Nominal bit time is taken the data bit time is discarded.

For CANFD configuration, you can have tow bitrates on a CAN frame: bitrate for the arbitration phase and another bitrate for the data phase.

refer to this link.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

View solution in original post

SofLit · ‎2024-03-26

It depends on what mode you configured for your FDCAN peripheral.

Did you configure it in Classical mode? i.e. CAN2.0 of CANFD?

For Classical CAN, only Nominal bit time is taken the data bit time is discarded.

For CANFD configuration, you can have tow bitrates on a CAN frame: bitrate for the arbitration phase and another bitrate for the data phase.

refer to this link.

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

CTabo.1 · ‎2024-03-26

Thank you very much.

Yes, have configured the peripheral in classical mode.
So I just have to configure the nominal bit time parameters, while leaving the data bit time parameters at their default values. Isn't it?

I have always worked with CAN 2.0A, and I don't know the FDCAN extended features.

Regards,
Carlo

SofLit · ‎2024-03-26

Yes, have configured the peripheral in classical mode.
So I just have to configure the nominal bit time parameters, while leaving the data bit time parameters at their default values. Isn't it?

Yes it is. keep them at default values. They are discarded by the CAN cell.

I have always worked with CAN 2.0A, and I don't know the FDCAN extended features.

It's time to start ;)

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

CTabo.1 · ‎2024-03-26

It's time to start ;)

Yes you are right! :grinning_face_with_sweat: