AURIX™ Forum Discussions

[User15955]

Hi,

Is there any Application Note/sample code for Aurix TC39x available for CAN auto Baud rate detection?
In AURIXTC3XX_um_part2_V1.2.0.pdf, there is mentioned about "Restricted Operation Mode", which can be used to detect Baud rate.


Thank you.
Naveen

[NeMa_4793301]

Hi Naveen. You should update your User Manual - 1.5 is the latest 🙂

40.3.2.1.5 Restricted Operation Mode
The Restricted Operation Mode can be used in applications that adapt themselves to different CAN bit rates. In this case the application tests different bit rates and leaves the Restricted Operation Mode after it has received a valid frame.

I'm not exactly sure what Bosch meant here, but I don't think it's as fancy as auto baud rate detection. There are simply too many knobs in CAN timing for an auto baud rate to complete in a reasonable time frame.

If you could fix a number of the parameters, then it wouldn't be so hard - for example, if you knew the sampling point, and the SJW, you could use Restricted Operation Mode to try out 125K, 500K, and 1Mbit for a few milliseconds, and see which one worked.

In any case, there is no sample code available.

[User15955]

UC_wrangler wrote:
Hi Naveen. You should update your User Manual - 1.5 is the latest 🙂


I'm not exactly sure what Bosch meant here, but I don't think it's as fancy as auto baud rate detection. There are simply too many knobs in CAN timing for an auto baud rate to complete in a reasonable time frame.

If you could fix a number of the parameters, then it wouldn't be so hard - for example, if you knew the sampling point, and the SJW, you could use Restricted Operation Mode to try out 125K, 500K, and 1Mbit for a few milliseconds, and see which one worked.

In any case, there is no sample code available.

ok. The approach you mentioned is also J1939-16 spec. Thank you.

[NeMa_4793301]

Thanks for the pointer - I'll check that out.