FDCAN Bus Configuration Issue: Error at Higher Bit Rates

[Dev_k]

Hello Everybody,

MCU: STM32H750XB (STM32H750DK Discovery Kit)
FDCAN Clock : 40MHz

I'm experiencing an issue with my FDCAN bus configuration where the node enters Error state and issue persists with any data rate higher than the nominal rate of 500 kbps.
But it works under Nominal Bit Rate: 500 kbps Data Bit Rate: 500 kbps.

Questions

• Is there a known limitation with running data bit rates higher than nominal bit rates on the STM32H750?
• Are there specific timing parameters I should adjust for higher data bit rates considering the FDCAN clock as 40 MHz?

Below,I have attached the main.c and IOC files for your reference.

Regards,
Dev

[SofLit]

Hello what "Higher bitrate" you are considering?

Please refer to this article: 

STM32 FDCAN running at 8 Mb/s on NUCLEO boards

Also to this article: FAQ: Fixing STM32 FDCAN communication disruptions - APB bus, kernel, and time quanta clocks

[SofLit]

And here you are setting the bitrate to 400kb/s not to 500kb/s

[Dev_k]

I have already went through with these articles but didn't help me any particular way.

If i am trying any bit rates higher than 500kbps for both nominal and data bit rate i am not receiving any data on FDCAN bus but If am setting it 500kbps or less it's working fine.

I am trying to configure my STM32H750dk in bit rate mentioned below:

Nominal Bit Rate 500 kbps and for this I want Data Bit Rates to be set as 1Mbps,2Mbps,5Mbps and 8Mbps 
Nominal Bit Rate 1Mbps and for this i want Data Bit Rates to be set as 1Mbps,2Mbps , 5Mbps and 8Mbps respectively.


And also is there any way to get the tested timing parameters for both Nominal and Data(Time Seg1,Time Seg2,Prescaler,SJW).

I was using KVASER calculator to calculate these timings


Regards,
Dev

[Dev_k]

where can i see this info that what my baud rate is other than kvaser calculator

[SofLit]

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@Dev_k wrote:

I have already went through with these articles but didn't help me any particular way.

---

Sorry but how? There is an example on H7  at 8Mb/s! you can inspire from it.

At this stage need to start with Loopback mode and check if you get the same behavior before going ahead with Normal mode. 

+ Avoid any internal RC clock source such as HSI CSI etc for CAN/FDCAN configuration: refer to this article.

[Dev_k]

Yes,
I'll check out the loopback mode and then go to normal mode.
I'll get back ASAP.

Regards,
Dev