Rx Errors on CAN when more than 2 devices are used

[misbahrex]

We are noticing Rx Errors (logged through watch -n 0.1 ifconfig) when the number of devices on our CAN bus increases to more than 2 or 3. The data is being sent at 500Kbps @ 50Hz. While these same devices (10 of them) work well on other systems (that doesn’t uses the Jetson Orin).
Is there a limitation as to how many devices or frequency the Orin can work reliably at ?
Unfortunately, the errors are causing some of our devices to fall off (as a fail-safe) the bus, which we cannot afford to. We can hardly keep all of them running for more than 2-3 mins.
I’m open to lowering the bit-rate if that’s the issue. Any suggestions are helpful.

[KevinFFF]

Hi misbahlabs,

Are you using the devkit or custom board for Orin NX?
What’s your Jetpack version in use?

@misbahrex

when the number of devices on our CAN bus increases to more than 2 or 3.

Could you share the block diagram of your connections for more than 2 CAN devices?

Moreover, do you use the exact same commands to setup all the CAN devices?
Please share the steps how you configure the CAN device and also the dmesg for further check.

[misbahrex]

Hi Kevin,
Thank you for getting back.

@KevinFFF

Are you using the devkit or custom board for Orin NX?
What’s your Jetpack version in use?

I’m using the devKit and Jetpack 35.2

@KevinFFF

Could you share the block diagram of your connections for more than 2 CAN devices?

Please find attached block diagram with notes for reference.

The commands are different to each of the CAN devices but in the same format and size.
The data is being sent a 50Hz (20ms). It is initiated by the Jetson-Orin and the controllers respond after receiving the commands.
We see Rx Errors on ifconfig (on the Jetson Orin’s side) after a few seconds and they ramp up quickly .

I did come across this note in configuring clock frequency documentation, that tells we need to switch on PLLAON for better accuracy when using CAN. The PLLAON being disabled be the cause of our issue?

You may want to enable PLLAON to achieve a higher clock rate or more accuracy in certain use cases like CAN and PWM. You can do this by first adding PLLAON as a possible parent of a clock, then setting the parent of the clock to PLLAON.

[KevinFFF]

@misbahrex

Please find attached block diagram with notes for reference.

Why your CAN devices are connected one by one rather than connecting them on the same CAN-H and CAN-L as the following link showed?
Connecting multiple microcontrollers to a CAN bus - Electrical Engineering Stack Exchange

@misbahrex

The commands are different to each of the CAN devices but in the same format and size.

Could you share the exact command you used for each CAN device?

@misbahrex

I did come across this note in configuring clock frequency documentation, that tells we need to switch on PLLAON for better accuracy when using CAN. The PLLAON being disabled be the cause of our issue?

PLLAON seems valid for T194 platform and not relating to your case (Orin NX).