Reading data with BRS on fdcan line

[CANZT-FD]

I am using STM32H5RE23T6.

I implemented the function of receiving data from the FDCAN line.

When I select FDCAN mode without BRS, it works without any problems.

When I select with BRS mode.
I set the arbitration phase to 1mbps.
I set the data phase to 8 mbps.

I cannot receive 8Mbps data in BRS mode.

I set the data phase speed to 2Mbps. I can receive data in BRS mode, but I cannot receive data at 8Mbps.

I have 2 reasons for this.

Firstly, the can transceiver may not support this speed.
The can transceiver I use is TCAN334D.
It says up to 1 Mbps in the datasheet, but I was able to get 2Mbps as well.

My other reason is
HAL_FDCAN_ConfigTxDelayCompensation and HAL_FDCAN_EnableTxDelayCompensation

We can send data up to 8Mbps using the functions, I saw on the forum that it says so in this link.

But I don't know how to do it. Can anyone explain in more detail?

[SofLit]

Hello,

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@CANZT-FD wrote:

Firstly, the can transceiver may not support this speed.
The can transceiver I use is TCAN334D.
It says up to 1 Mbps in the datasheet, but I was able to get 2Mbps as well.

No, the TCAN334D datasheet says that it could reach 5Mb/s:

So that's normal you didn't get it worked at 8Mb/s but worked at 2Mb/s.

Replace the transceiver: example: MCP2561FD or MCP2562FD to reach 8Mb/s.

Meanwhile, read this article: STM32 FDCAN running at 8 Mb/s on NUCLEO boards: Same bitrates you are using

Hope I answered your question.

[CANZT-FD]

Thanks for your answer.

The speed up to 5Mbps is written for TCAN33..G series, I am using the D series. so it may not support 5Mbps speed..

I can change the transceiver. I can use MCP series, but I am wondering if it can be fixed with the functions written here..

https://community.st.com/t5/stm32-mcus-products/stm32h7-fdcan-8-mbit-s-setup-docum-unclear-sync-seg/td-p/79992

[CANZT-FD]

If it could support up to 5 Mbps speed. It should have supported 4Mbps speed, but it does not work at 4Mbps.

[CANZT-FD]

uint32_t TdcOffset = 5;
HAL_FDCAN_ConfigTxDelayCompensation(&hfdcan1, TdcOffset, 0) ;

HAL_FDCAN_EnableTxDelayCompensation(&hfdcan1);

I can't decide whether it can be solved with the above functions or whether the problem is hardware related.

[CANZT-FD]

Thanks for your answer.

The speed up to 5Mbps is written for TCAN33..G series, I am using the D series. so it may not support 5Mbps speed..

I can change the transceiver. I can use MCP series, but I am wondering if it can be fixed with the functions written here..

https://community.st.com/t5/stm32-mcus-products/stm32h7-fdcan-8-mbit-s-setup-docum-unclear-sync-seg/td-p/79992

[SofLit · Accepted solution]

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Ok but D suffix was not listed in their table:

Enable the delay compensation but the most important thing is to use a transceiver that can reach 8Mb/s.

And it worked at 2Mb/s because the chip manufacturer has a margin and that could not work for all the conditions. 

Hope that answers your question.