PmodCAN not returning good CAN data

[JJ Fenstermaker]

We've been testing the PmodCAN transceiver with Particle Argon boards.  We're confident that we have the hardware set up right - loop back mode works flawlessly.  However when we put the device in listen only or receive mode we don't get the data we're expecting off of the CAN bus.  We're using a CAN bus analyzer for validation.  We have the part running at 125 Kbps with a 16 MHz. clock, and we're using the standard MCP_CAN library.  Any ideas as to why our data doesn't match?

[jpeyron]

Hi @JJ Fenstermaker,

Here is the Pmod CAN resource center that has Arduino and MPLABx demo code.  We do not have code for the Particle Argon Web IDE.  Can you post the Web IDE code you are using for the loop back, rx and tx?

thank you,

Jon

 

 

 

[JJ Fenstermaker]

Jon,

We're getting good data now but have run into two new issues

We're missing messages (we're using an analyzer to validate the data)

If we try to use a filter in the setup() function we get an assert.  It doesn't assert in the main loop but it doesn't filter data either.

Here's the code - the library and the test code.  Any ideas?

:

CAN_code.7z

[jpeyron]

Hi @JJ Fenstermaker,

I am glad to hear that you have made some progress. I'm not seeing anything specifically wrong with your code. You might benefit from exposing the signals between the Pmod CAN and your board to see exactly what is happening. Also have you tried different data rates for transmission? 

thank you,

Jon

[JJ Fenstermaker]

We've narrowed the issue down to a problem with extended messages - when we send them we get unpredictable results - one of the peripherals on the CAN bus powers down our system after we send the message.  We've reached out to the peripheral manufacturer for assistance.  Thanks for your reply!

We also have CAN bus analyzers - everything on the bus looks OK.

John

 

[jpeyron]

Hi @JJ Fenstermaker,

Glad to hear that you have narrowed down the issue and have reached out to the peripheral manufacturer.

thank you,

Jon