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VPras
VPras
Associate III
November 22, 2019
Question

bit timing issue in CANFD

  • November 22, 2019
  • 3 replies
  • 1296 views

Hi,

i have STM32H7 Nucleo board, i'm trying to implement CAN-FD. so i was trying to send some data over CAN-FD to CAN-Analyser. For bit timing calculation i'm using STM32H743I-EVAL example as reference .

fdcan_ker_ck - 20Mhz, Time_quantum- 50ns, Propagation_segment- 23 tq, Phase_segment_1- 8 tq, Phase_segment_2- 8 tq, Synchronization_Jump_width - 8 tq, Bit_length - 2 us, Bit_rate- 0.5 MBit/s.

this i used it for both nominal and data..But when i use it can analyser the bit timing doesn't match.i used these following documents for reference but still couldn't solve it

https://www.can-cia.org/fileadmin/resources/documents/proceedings/2013_hartwich_v2.pdf

https://www.stmicroelectronics.com.cn/content/ccc/resource/training/technical/product_training/group0/8b/ec/0c/16/9d/fa/49/59/STM32G4-Peripheral-Flexible_Datarate_Controller_Area_Network_FDCAN/files/STM32G4-Peripheral-Flexible_Datarate_Controller_Area_Network_FDCAN.pdf/_jcr_content/translations/en.STM32G4-Peripheral-Flexible_Datarate_Controller_Area_Network_FDCAN.pdf

Thanks,

Vimal

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3 replies

VPras
VPrasAuthor
Associate III
November 25, 2019

Hi,

I'm getting some data in analyser but couldn't able to decode the data, this is because of bit timing issue or anything else. i'm attaching the screenshot, please have a look into it.

0690X00000AsOEUQA3.png

Auto-retransmission is happening because my Nucleo-board is not getting any acknowledgement

Thanks,

Vimal

VPras
VPrasAuthor
Associate III
November 29, 2019

Hi,

Issue solved, there is issue with the crystal oscillator.Now it works fine with internal oscillator.

thanks,

Vimal

VAgga
VAgga
Associate III
March 8, 2021

Hi VPras,

I am also facing the same issue. Bit timings are not matching when i see it in the oscilloscope. I am using NUCLEO-H743ZI board provided by ST partner.

Should i change the crystal oscillator on the board? Board is provided by ST partner, then how can this be the issue of the crystal oscillator?

Any help would be highly appreciated.

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