blinky example waiting for embassy_stm32::rcc::init() on STM32H735 Discovery Kit

[wagcampbell]

Hi there 👋

I recently attempted to run the blinky.rs example on an STM32H735 Discovery Kit.

I updated the .cargo/config.toml runner:

runner = 'probe-run --chip STM32H735IGKx'

and Cargo.toml embassy-stm32 features list:

embassy-stm32 = { version = "0.1.0", path = "../../embassy-stm32", features = ["defmt", "stm32h735ig", "time-driver-any", "exti", "memory-x", "unstable-pac", "chrono"] }

After inspecting the backtrace, it seems to be stuck here:
https://github.com/embassy-rs/embassy/blame/main/embassy-stm32/src/rcc/h.rs#L334

    // Validate the supply configuration. If you are stuck here, it is
    // because the voltages on your board do not match those specified
    // in the D3CR.VOS and CR3.SDLEVEL fields. By default after reset
    // VOS = Scale 3, so check that the voltage on the VCAP pins =
    // 1.0V.
    #[cfg(any(pwr_h7rm0433, pwr_h7rm0399, pwr_h7rm0455, pwr_h7rm0468))]
    while !PWR.csr1().read().actvosrdy() {}

I probed 1.3V on the the VCAP pins here:

This issue might be related:
embassy-rs/stm32-data#260

That said, I don't have a strong grasp on how this STM32 data is generated.
I'm pretty early investigating this and plan on reading over RM0468 and studying this more.

Thanks in advance!

[wagcampbell]

Hello again,

So, I think I've figured out what's wrong.

I realized the default rcc supply config doesn't match the dev kit. From the dev kit user manual:

So, I tried changing the example's rcc supply config to SupplyConfig::DirectSMPS.

    let mut config = embassy_stm32::Config::default();
    {
        use embassy_stm32::rcc::*;
        config.rcc.supply_config = SupplyConfig::DirectSMPS;
    }
    let p = embassy_stm32::init(config);

Unfortunately, this didn't resolve my issue. I also had to perform these steps as documented in the user manual:

I haven't figured out where in the reference manual this 'deadlock' state is documented.
That said, the example runs now after performing those recover steps.

Thanks!