RE: nRF5340 Not Receiving CAN Traffic

piper8 — Tue, 17 Sep 2024 22:04:33 GMT

I found the problem, I was using GPIO 0.00 as the CIPO of my SPI bus, which is one of the low frequency crystal oscillator (LFXO) pins. The LFXO must be disabled with:

CONFIG_SOC_ENABLE_LFXO=n

to use this pin for other purposes. CAN works properly now.

RE: nRF5340 Not Receiving CAN Traffic

piper8 — Mon, 16 Sep 2024 19:36:12 GMT

That's good advice, thank you. After digging through the controller driver (and the nRFX SPIM driver,) I've found a few tings. It looks like the interrupt code in the driver is triggered, but the interrupt flags don't make it there (the interrupt handler is fed 0x00 instead of the actual flag byte, 0x04.) I'm trying to track this down through the SPI driver code, but it is crashing when I use printk very much, probably because this is timing sensitive code, and I'm inserting a bloated monster called printk into it. The stack overflows/improper EPSR use/etc fatal errors have variously implicated timing code or the printk function. I'm trying to find another way to extract data from here, probably by copying it elsewhere in memory, to then print it from a non timing critical context (main, some thread, etc.) However, I don't know how to do this from a driver, when the OS has created several levels of separation between the driver and somewhere I can safely run complex code like printk. Is there a good way to stick a pointer to my harvested data in memory somewhere, and then find and use it from some other, unrelated code? I figure there has to be a system call to do this kind of thing.

I also found that the ISO-TP sample does work, receiving data and everything, but I can't figure out what it's doing differently (or how it could be different, since they both use the same MCP2515 driver.)

RE: nRF5340 Not Receiving CAN Traffic

Turbo J — Sat, 31 Aug 2024 07:59:54 GMT

Once you see the data going into the NRF MCU on the SPI lines, its a good idea to look at the actual mcp2515 driver source code.

Maybe hook up a debugger and check what its doing. You probably missed some minor detail in the driver API, and reading the source usually makes this kind of issue obvious.