Feature gate devices

[MabezDev]

Devices that need to be feature gated (taken from stm):

L4x6

• stm32l496
• stm32l4A6
• stm32l476
• stm32l486

L4x5

• stm32l475

L4x3

• stm32l433
• stm32l443

L4x2

• stm32l452
• stm32l462
• stm32l432
• stm32l442
• stm32l412
• stm32l422

L4x1

• stm32l471
• stm32l451
• stm32l431

If you fancy feature gating a device, you will need to go through reference manual for the chip family and feature gate the relevant peripherals. These are normally found in footnote e.g *not present on the stm32l4blahblah etc.

[twilco]

Are we limited by the fact that the stm32-rs library only specifies families for the l4 series whereas the f4 series has individual chips exposed?

[MabezDev]

I'm pretty sure those are the chip families for the f4, as in the f4 hal crate there are more devices than there are listed in in the stm32-rs crate. I've updated the issue to include a list of the devices, which should make it easier to track what needs feature gating.

[twilco]

Thanks for clarifying. I have an STM32L433 and would love to lend a hand with this issue.

[MabezDev]

Awesome! If you've got any questions you can normally find me in #rust-embedded on irc.mozilla.org

[mathk]

The L4x6 family is even split into those that have HSI16 and those that does not. How do you see that ?

[ryan-summers]

I'm in the process of bringing up a project using the STM32L452 and I'm starting to see the need here (e.g. SPI2 is not exposed via the HAL, but the device has SPI1, SPI2, and SPI3). Since I'll likely need to implement this for my project, I'd be happy to contribute it back to this repository.

Of interest is Section 1.5 of DM00151940, which lists Product-specific features for the STM32L4 family:

[mehmetalianil]

I have an STM32L475, and would love to contribute.

[DrTobe]

As far as I have understood, there are no chip/device-specific feature gates implemented currently, since I do not see any appropriate features (e.g. stm32l431) in Cargo.toml, is that correct?

If so, what is the current plan to progress here? Feature-gating a whole device with all peripherals seems like a huge amount of work to me. Maybe, this is the reason why this has not yet been done? Would it be feasible to keep the device-families as features (each feature activating the minimum subset) but additionally introduce chip-specific features which depend on the device-family-features? With that approach, chip-specific peripherals could be added without breaking anything because the current minimum subset would be kept and automatically be activated when enabling one of the chip-specific features.

[korken89]

Hi, this is correct.
I am not sure on how to proceed here, but we do need to feature gate on each MCU.
If you have an idea I'm very open to input!

[mehmetalianil]

If you fancy feature gating a device, you will need to go through reference manual for the chip family and feature gate the relevant peripherals. These are normally found in footnote e.g *not present on the stm32l4blahblah etc.

@MabezDev Footnotes in the Reference manual, or the tail of the source code? I would like to use feature gating to get accustomed to embedded-rust. Where shall I start?