Support for the C0 series

[FeldrinH]

Are there any plans to support the STM32C0xx series? I'm particularly interested in STM32C071 for its USB capabilities.

[David-OConnor]

I would love C0 support, but don't have any hardware, and not sure what state the C0 PAC is in. WOuld accept a PR, even if limited functionality, e.g. only a few peripherals supported. Is it most similar to G0, you think?

[FeldrinH]

I've heard it is similar to G0, but I have not compared the reference manuals myself.

[FeldrinH]

We will probably use C071 for a project in the coming months so then I will have plenty of hardware to test with if that would be helpful.

[FeldrinH]

As for the PAC I'm not really sure how to evaluate it's maturity, since it's autogenerated. It does exist, it supports STM32C011, STM32C031 and STM32C071 and has the USB registers for C071.

[David-OConnor]

Obstacle: c0 was PAC was added as 0.16.0. (The latest as of a month ago).

In order to conserve most of the code, we'd probably have to update the others as well. (They're on v15, the prev release, a few years old). This may be a big undertaking I hoped to avoid. In particular, there are a lot of cases where the code is the same, but they made fields private and exposed methods. So a lot of adding ()... all over the code base.

Not pushed yet, but I just added the features, dependency, and some setup code for C0.

[FeldrinH]

In order to conserve most of the code, we'd probably have to update the others as well. (They're on v15, the prev release, a few years old). This may be a big undertaking I hoped to avoid. In particular, there are a lot of cases where the code is the same, but they made fields private and exposed methods. So a lot of adding ()... all over the code base.

That is indeed quite annoying, but the update probably needs to be done eventually, so might be good to get it out of the way now.

I'll fiddle around a bit and see if I can automate the more rote parts of the migration.

[FeldrinH]

I think I can automate a majority of the migration. Would you be open to a PR moving the entire HAL to version 0.16.0 of PAC-s?

[David-OConnor]

I appreciate it! But: No; I'm working it RN. Most of the way there I think? Overall has a net reduction in code in a few areas due to consolidating the API between variants where possible. (Where the regs are the same but the prev PAC/SVD was different), and using numerical values for channels to greatly simplify code in some cases like DMA. (Was prev only enumerated for H7; now it's all).

Some minor syntax changes all over too, ofc, like the one I mentioned.

What would be helpul from PR perspective: Once the PAC upgrade is done and I hit a stopping point on C0 initial stuff: Patching in anything I missed for C0 or that isn't working right, testing on hardware for it etc.

[David-OConnor]

Basic work on the PAC upgrade done. Some variants dont' compile. C0 needs work. Like the PAC UG, it's just tedium and some reference manual dives. Will take PRs.

[FeldrinH]

By the way, do you have some kind of test suite or documented testing procedure for testing the HAL on new hardware?

[David-OConnor]

No

[David-OConnor]

What peripherals are on the C0 board you're using, and which variant is it? I will focus on those so you can test it.

[FeldrinH]

The variant is STM32C071RB. Was planning to buy a NUCLEO-C071RB devboard or something equivalent. I don't know all the peripherals but the ones we will use are the USB (as device), SPI and GPIO.

[David-OConnor]

Here is the rub:

Generally, things get in a good state for MCUs and peripherals that someone has used, and either cross-checked the manual with, or tried and found/fixed problems. Or, for peripherals that are the same as one that has been tested as such. So, G4 and H7 are very well supported because I've done a lot of work on them using most of their periphs.

I think the best way to work this is to focus on getting the basics (RCC, Flash memory, and GPIO) working on C0, through some trial and error, then getting SPI and USB working. I think this will be easy since that's a narrow feature set.

[FeldrinH]

I don't know all the peripherals but the ones we will use are the USB (as device), SPI and GPIO.

Oh, and we'll be using PWM as well.