Nucleo STM32H753 + rust 1.86

[lucasw]

I successfully ran blinky, button, and ethernet examples with the STM32H753 Nucleo board (https://www.st.com/en/evaluation-tools/nucleo-h753zi.html) after making the changes in this branch:

https://github.com/lucasw/nucleo-h7xx/tree/stm32h753

I disabled deny warnings after getting these with the ethernet example (is it because newer rust versions are more strict?):

error: creating a shared reference to mutable static is discouraged
   --> src/ethernet.rs:162:13
    |
162 |             ETHERNET_MUTEX.borrow(cs).replace(None);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^ shared reference to mutable static
    |
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2024/static-mut-references.html>
    = note: shared references to mutable statics are dangerous; it's undefined behavior if the static is mutated or if a mutable reference is created for it while the shared reference lives
note: the lint level is defined here
   --> src/lib.rs:1:9
    |
1   | #![deny(warnings)]
    |         ^^^^^^^^
    = note: `#[deny(static_mut_refs)]` implied by `#[deny(warnings)]`
...

---

Some things I'd like to try next:

• upgrade stm32hxx-hal to 0.16
• hprintln with semihosting
• serial
• canbus

I'm new to embedded with rust before but I think I can drop to the hal level for serial or canbus or anything else missing here, use examples from st32hxx-hal or adapt them from elsewhere.