Geir & Greg,

first of all, I did an over-optimization mistake in the RxCallback: the return after fetching the frame must always be true -- fix is pushed.

That has caused frames to get lost so you should apply this fix first.

Am 31.12.2017 um 01:00 schrieb Geir Øyvind Vælidalo:

I did a test where I created three counters.
One went into MCP2515_isr and counts every interrupt.

One was added as the first code line in mcp2515::RxCallback.

And the third one was added to RxCallBack, but right before we read the CAN frame via SPI that will end up in IncomingFrame. I.e. should be a count of every CAN frame.

This is what I got:

OVMS > can can2 status

CAN: can2

Mode: Active

Speed: 100000

Rx pkt: 82

MCP2515_isr:   239

RxCallback1:   320

RxCallback2:   295

Rx err: 0

Tx pkt: 0

Tx err: 0

Err flags: 0x2040

These numbers puzzles me. Shouldn’t RxCallback1 and RxCallback2 be less or equal to MCP2515_isr? Where does these extra 81 calls come from? I’m missing something here...

No, that's expected behaviour. The MCP2515 has two RX buffers plus error conditions. The framework is designed to loop RxCallback over an IRQ event until all buffers and error conditions have been processed, so RxCallback counters should always be >= ISR count.

Also, RxCallback2 is much bigger than Rx pkt, which means not all frames are sent to IncomingFrame.

That's in part due to my bug, but it also can happen under normal conditions, as an error IRQ will also trigger the RxCallback but not return a frame to be processed.

What does the 0x2040 means? And where do that number comes from?

That's constructed in line 293 from the error interrupt flags and the error register. The lower 8 bits are in the image I sent, the upper 8 bits are

// MERRF 0x80 = message tx/rx error // ERRIF 0x20 = overflow / error state change

Regards,
Michael

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