Having issues with setting filters with the FlexCAN library!

[tadzio93]

Hey guys, I've been using the FlexCAN library for some time now, but never used hardware filters. Trying to implement them now, but am having some issues.

• Tool: Teensy 3.6
• FlexCAN version: the one included in the most recent Teensyduino

EDIT:
My testing method is that I have a CAN2.0 device sending out a frame every 50ms with ID 0x720. I seem to always be getting these frames no matter how I set up my filter and mask.

CAN_filter_t hs_filter;
hs_filter.ext = 0;
hs_filter.rtr = 0;
hs_filter.id = 0x5FF;
 
Can0.begin(500000);

for (int c = 0; c < 14; c++) // 14 is from NUM_MAILBOXES - numTxMailboxes
{
   Can0.setMask(0xFFFF, c); // setMask takes uint32_t mask variable.  0xFFFF should only accept the one ID.
   Can0.setFilter(hs_filter, c);
}

I have also tried editing the FlexCAN.cpp. When I run the Can0.begin, it initializes with a defaultFilter of 0,0,0 for ext, rtr, and id respectively, as well as setting each mask to 0.

  CAN_filter_t defaultFilter;
  defaultFilter.ext = 0;
  defaultFilter.rtr = 0;
  defaultFilter.id = 0;
  for (int c = 0; c < NUM_MAILBOXES - numTxMailboxes; c++)
  {
     setMask(0, c);
     setFilter(defaultFilter, c);
  }

I changed this to:

CAN_filter_t defaultFilter;
defaultFilter.ext = 0;
defaultFilter.rtr = 0;
defaultFilter.id = 0x5FF;
for (int c = 0; c < NUM_MAILBOXES - numTxMailboxes; c++)
{
   setMask(0xFFFF, c);
   setFilter(defaultFilter, c);
}

Still no luck.

If anyone has any advice I would greatly appreciate it! I looked to Paul's github, but it seems to be an older version of the FlexCAN library.

Thanks,

 

[tadzio93]

I figured I'd reply and say I found the issue!

The mask value in setMask is uint32_t which should be 0xFFFFFFFF, NOT 0xFFFF.

Once I made this change, I was able to filter for just that ID.