Warning

This post was published 111 days ago. The information described in this article may have changed.

Info

This post is auto-generated from RSS feed The Rust Programming Language Forum - Latest topics. Source: Setting GPIO High or Low generates same binary Rust Embassy STM32

When my code sets GPIO High or Low, rustc still generates the exact same binary. The binary generated is only 24 bytes long and I don't think it contains any instructions relating to GPIO.

Here is my Rust code (I am aware of the trivial warnings):

#![no_std]
#![no_main]

use embassy_executor::Spawner;
use embassy_stm32::gpio::{Level, Output, Speed, Pin};
use embassy_stm32::Config;

#[embassy_executor::main]
async fn main(_spawner: Spawner) {
    let mut config = Config::default();
    let p = embassy_stm32::init(config);

    let mut pa3 = Output::new(p.PA3, Level::Low, Speed::VeryHigh);

    pa3.set_low();

    loop { }
}

#[panic_handler]
fn panic(_info: &core::panic::PanicInfo) -> ! {
    loop { }
}

I ran cargo build and took the MD5 hash of the binary, then ran cargo clear which deleted the binary. Then I changed 2 lines:

let mut pa3 = Output::new(p.PA3, Level::Low, Speed::VeryHigh);
changed to:
let mut pa3 = Output::new(p.PA3, Level::High, Speed::VeryHigh);

And pa3.set_low(); changed to: pa3.set_high();

I ran cargo build and took the MD5 Hash of the new binary and it was exactly the same as the old one. Additionally, I added lines to set states of other pins like A4 to high, and the binary is also the same.

I tried to be very thorough as to not make any trivial mistakes. Here is what I know:
Even when I change the code as I described, the compiler still produces the exact same 24 byte binaries. Even when I add:

    pa3.set_high();
    embassy_time::Timer::after_millis(500).await;
    pa3.set_low();
    embassy_time::Timer::after_millis(500).await;

inside the loop, nothing changes.

Using advanced analysis (ChatGPT), the binary contains no instructions relating to GPIO. Maybe they are being optimized out for some reason? I am using Rust with Embassy on an STM32WLE5CBU6.

Additional Files

Cargo.toml

[package]
name = "spider-router"
version = "0.1.0"
edition = "2024"

[dependencies]
cortex-m-rt = "0.7.5"
embassy-executor = { version = "0.9.1", features = ["arch-cortex-m", "executor-thread"] }
embassy-stm32 = { version = "0.4.0", features = ["stm32wle5cb"] }
embassy-time = "0.5.0"

I will include any other config files as needed. Thanks.

2 posts - 2 participants

Read full topic

🏷️ Rust_feed