This is a rather strange question, but tell me please how can I get unfiltered data via CanH and CanL?
What I mean is that if I use the normal CAN receiver sketch, it looks like there is no data at all because the data actually is not a Can message (but it goes through Can Bus) and that's why it's being filtered. But there is a message because the RxLED is blinking.
normally if you are using an mcp2515 chip, assuming
(1) your code to read out the CAN messages are correct, then unless the (2) receiving frames are ERROR frames or (3) you have your CAN wires inverted,
If all of the above are not applicable, then you should be reading your CAN frames on your arduino.
hope that helps...
The RxLED is probably showing the activity on the signal line going from the CAN transceiver chip into the MCP2515, therefore it doesn't necessarily indicate that the MCP2515 itself is successfully decoding the data.
If the library you are using supports a loopback test mode then I would suggest that you use first use that to prove that the MCP2515 is working correctly.
If your MCP2515 is working correctly, then there are two more things to consider.
- A common problem is a mismatch between the crystal frequency the library is using (often 16 MHz) and the actual crystal frequency used on the MCP2515 board or shield (sometimes 8 MHz).
- Is your CAN bus running at 1MBPS? If so a board/shield using an 8MHz crystal is too slow to be able to decode the data.
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