CAN Protocol Trigger for Logic Analyzer

[jfrenzel]

I am able to capture a CAN message using the logic analyzer with a "Simple" trigger of falling edge on the TX line (polarity low), but have not succeeded in triggering using the "Protocol" trigger.

Attached is a screenshot of a transmit capture using "Simple" and the waveform looks correct. However when I use the attached "Protocol" settings, the analyzer never triggers.

What am I missing?

 

 

[attila]

Hi @jfrenzel

In your data the 'Substitute remote request' (SRR) is 0 but it should be 1 for extended format.
https://en.wikipedia.org/wiki/CAN_bus
The triggering includes this bit in the sequence and expects 1, it receives 0 and does not trigger.

[attila]

Hi @jfrenzel

With the latest beta version it seems to me working correctly. Please try this version:
https://forum.digilentinc.com/topic/8908-waveforms-beta-download/

In case it is still not working please save and attach (or send me) the workspace (or the acquisition data).

It might useful for you the Protocol/CAN to receive and send data.

 

 

[jfrenzel]

Downloaded thelatest Beta (3.11.30 64-bit) and have the same problem: the Logic Analyzer triggers fine with a simple, falling edge trigger on DIO6 (RX); doesn't work with the Protocol trigger. I'll attach both my screenshot and workspace.

The problem may be that you appear to be using Waveforms Protocol Analyzer tool to create the CAN message, where as I am connecting to the PIC32 CAN pins of an actually CAN bus that is sending and receiving CAN messages using the PIC32. What I'm implying is that perhaps the Waveforms Protocol Analyzer is correcting for mistakes in the Logic Analyzer.

Just a thought ...

 

 

CAN Workspace.dwf3work

[jfrenzel]

Well, I''ll be - you are absolutely correct! I was working off of a sample project from Microchip and didn't think to check whether they were forming the message correctly. (Interestingly enough, the PIC32 CAN controller doesn't care, because the bus seems to keep running.)

A big (BIG) thank you for  your help!