Support for STM32 L1-series

[postlund]

I'm currently looking around for a small RTOS to use in a new project for a customer and Zephyr matches more or less perfectly what I need. My current problem is that the CPU used in the project is based on the STM32L1 series (STM32L152RE to be more exact) and Zephyr does not seem to support that at the moment. So I would like to request support for L1 to be added.

https://www.st.com/en/embedded-software/stm32cubel1.html

[erwango]

Hi @postlund ,

Thanks for your interest for Zephyr and STM32.
Indeed L1 is one of the few STM32 series not yet ported into Zephyr. All other series have been ported by the community and often by new members like you.
This is some work, but mostly copy/paste and adaptation of existing code. It is the perfect task to dive into Zephyr and learn the basics. Also, doing this upstream work is usually quite formative to start to work with Zephyr community in general.
If you're interested in this journey, here are examples:
#7284 (STM32F7)
#7450 (STM32F2)
#5949 (STM32L0)

Of course people will help you during the review. And here are some few recommendations that are meant to fasten the review and upstream process:
-Split your work into small but coherent commits (hal, arch, dts, drivers, boards ..)
-Limit initial work to the basics drivers required for hello_world and blinky: clock_control, uart, exti, gpio, pinmux
-Port one board (ideally ST nucleo, disco) that can be used by others to check your work

Cheers!

[postlund]

Hi @erwango,

Thanks for the quick reply. I actually started a port last week and it seems quite straight-forward. But I'm new both to the STM32 processor family and zephyr, so it's a slow process (along with my time being limited). But I will try to make some PRs for the things I do and hopefully get things working bit-by-bit. Getting "hello world" working on my development board would be a splendid start.

Thanks again!

[Aukstkalnis]

As I understand @postlund did not finished STM32L1 MCU support, so I started to work on this.

[erwango]

@Aukstkalnis, work is actually completed and waiting for 1.15 merge window openning: #12354

[Aukstkalnis]

Good;-) I spent 1 day to write all GPIO alternate functions for all posible l1 pins and double checking everything😅 So i will check this pull request🙂

[erwango]

@Aukstkalnis , I don't know what was your ambition, but if you're looking for fun, STM32H7 series are yet to be ported on Zephyr ;-)

[Aukstkalnis]

My ambition was to add STM32L152C_Discovery board support to zephyr OS and have fun, but there was no STM32L1x support, so I searched open cases and pull request for STM32L1, found this case and didn't check attached cases because their titles did not contain string "STM32L1", so I jumped to conclusion that there is not support for L1 and started working on it :D With this pull request now I only need to add STM32L152C_Discovery board support :)

[erwango]

So you lost one day, but gained 10 then :-)
This is great, have fun with zephyr on STM32!

[Aukstkalnis]

Thank you :) 👍

[Aukstkalnis]

I have one question about boards. I am planing to add STM32L152C discovery board support to zephyr. Can I add support on #12354 pull request, test it, then move changes to zephyr master that does not have STM32L1 support and generate pull request? Or should I generate pull request when STM32L1 support will be added?

[erwango]

You can push a PR with your board support which would include #12354. Then, once #12354 is merged you'll have to rebase and your commits will remain.

[takumiando]

This implementation doesn't work correctly.
#22078