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

[Oliver Hartkopp <socketcan@hartkopp.net>]

Hi Jacob,

On 30.08.22 14:59, Jacob Kroon wrote:

> On 8/29/22 15:53, Oliver Hartkopp wrote:

>> Regarding your problem:
>> "BUG! echo_skb 0 is occupied" should never show up but I wonder if you 
>> probably have another CAN specific problem with your setup.
>>
>> Did you set up a CAN network with at least two CAN nodes, identical 
>> bitrate settings and 2x120 Ohms (== 60 Ohms) termination between CAN_L 
>> and CAN_H?
>>
> 
> I have double checked that both endpoints of the network are terminated 
> with 120Ohm resistors, and when I check CAN_H/CAN_L in an oscilloscope 
> they look ok, and within the spec. voltage levels.

https://www.compulab.com/wp-content/uploads/2011/08/CM-iTC-Reference-Guide.pdf

"it is necessary to add transceiver
hardware (see the SB-iTC reference schematic)"

I assume you have a transceiver, right? ;-)

What is the other endpoint? The EG20T and another (automotive) ECU?

>> 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.

Best,
Oliver