STM32H7 Can Filter & Can bus-off State Handling

[henrykotze]

Exception handling for bus-off state in the STM32H7 driver, and first go at implementing the CAN filters

Based on the following STM32 Documents:
RM0433 - Reference manual for STM32H742, STM32H743/753 and STM32H750 Value line
AN5348 - Introduction to FDCAN peripherals for STM32 product classes
TN1367 - Bus off management in MCAN controllers

Context

• Our ESCs on powerup, causes the CAN bus to go into bus-off state. Currently their is no handling of this state in the STM32H7 driver, and results in the FMU to be 'kicked' off from the Canbus.

Implementation

• Added the can bus off state into the interrupt register, and handling this state. Currently in both interrupts, there is a check for whether this interrupt has been triggered, but it might only be necessary on one of them.
• Added Can filters, unsure whether they work as intended (I dont think they do), would be great if someone with more experience have a look at this.

[davids5]

See inline

[henrykotze]

Standard Filter Register

Extended Filter Register

Would be great if someone could have a peek if the way how I implement the filter are correct, because I am not too sure if they are working as intended.

[henrykotze]

@davids5 anything else here to do, except for squash comments?

I can confirm the bus is much more stable. We can short the CANH and CANL, and it will recover perfectly. The only thing I am unsure about is the filter implementation. @JacobCrabill do you have comments or suggestion to make? I just @ you due to your work on the initial driver work :)

[davids5]

@henrykotze LGTM but please squash/Fix it up the commits

[DronecodeBot]

This pull request has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:

https://discuss.px4.io/t/px4-community-q-a-july-12-2023/33086/4