Re: CM-ITC, pch_can/c_can_pci, sendto() returning ENOBUFS

[Oliver Hartkopp <socketcan@hartkopp.net>]

Hi Jacob,

On 01.09.22 11:38, Jacob Kroon wrote:
> On 8/30/22 21:15, Oliver Hartkopp wrote:

>> I assume you have a transceiver, right? ;-)
>>
> 
> Yes,, all nodes are using a TJA1050 transceiver
> (https://www.nxp.com/docs/en/data-sheet/TJA1050.pdf)

Good!

>> What is the other endpoint? The EG20T and another (automotive) ECU?
> 
> Currently I have 4 nodes in the network, EG20T is in one end.
> 

Ok, that's a good base for testing.

>>>> Do you have another CAN node which can be attached to the EG20T 
>>>> setup (e.g. some ECU or an USB CAN adapter)?
>>>
>>> Yes I do have a CAN analyser from Microchip. I guess I can record all 
>>> traffic with the analyzer, and compare it to what I see with "candump 
>>> can0" on the host. Or do you have some other suggestion ?
>>
>> Yes, please add the CAN analyzer from Microchip too!
>>
>> The problem with only two nodes is that you have to be very precise 
>> with bitrate settings and sampling points so that the receiving node 
>> needs to properly set the ACK to acknowlege the CAN frame.
>>
>> I had been working with a MSCAN system some time ago and that wasn't 
>> able to talk to a commercial CAN tool until I added another node (from 
>> another CAN tool provider).
>>
>> Maybe you can make the other node talk to the Microchip CAN analyzer 
>> and let the EG20T receive that traffic first.
>>
> 
> I used "candump can0 -l" on the EG20T host to capture the traffic, and 
> then connected an CAN USB analyzer to the network and used that to 
> capture the traffic. One thing sticks out. This is the log from the CAN 
> USB analyzer:
> 
>> ...
>> 505.7052;RX;0x464;3;0x01;0x01;0x00;;;;;;
>> 505.7052;RX;0x464;3;0x00;0x00;0x00;;;;;;
>> 505.7063;RX;0x65;64;;;;;;;;;

What should this be?

A length of 64 and no data ??

This is no valid CAN frame.

>> 505.7662;RX;0x440;3;0x32;0x20;0xFA;;;;;;
(..)

> 
> Note the third message from the top. This is what "candump" on the host 
> logs:
> 
>> ...
>> (1662022485.638794) can0 464#010100
>> (1662022485.638940) can0 464#000000
>> (1662022485.699405) can0 440#3220FA

The correct CAN frames are displayed correctly.

>> ...
> 
> It fails to see the 3rd message from the previous log. What would that 
> indicate ? The CAN analyzer sees the message, but the EG20T doesn't.

Don't know if this is an error on the CAN bus. You can also print error 
messages of detected CAN bus problems with adding an error message filter.

See 'candump -h' :

candump -l any,0:0,#FFFFFFFF
          (log error frames and also all data frames)


Best regards,
Oliver