stm32: Add F0 example

.github/workflows/rust.yml

@@ -88,6 +88,8 @@ jobs:
             target: thumbv6m-none-eabi
           - package: examples/stm32wb55
             target: thumbv7em-none-eabihf
+          - package: examples/stm32f0
+            target: thumbv6m-none-eabi
 
     steps:
       - uses: actions/checkout@v2

examples/stm32f0/.cargo/config.toml

@@ -0,0 +1,10 @@
+[target.thumbv6m-none-eabi]
+runner = 'probe-run --chip STM32F030F4Px'
+rustflags = [
+  # LLD (shipped with the Rust toolchain) is used as the default linker
+  "-C", "link-arg=-Tlink.x",
+  "-C", "link-arg=-Tdefmt.x",
+]
+
+[build]
+target = "thumbv6m-none-eabi"

examples/stm32f0/Cargo.toml

@@ -0,0 +1,29 @@
+[package]
+name = "embassy-stm32f0-examples"
+version = "0.1.0"
+authors = ["Thales Fragoso <thales.fragosoz@gmail.com>"]
+edition = "2018"
+resolver = "2"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+cortex-m = { version = "0.7.1", features = ["inline-asm"] }
+cortex-m-rt = "0.6.13"
+defmt = "0.2.0"
+defmt-rtt = "0.2.0"
+panic-probe = { version = "0.2.0" }
+rtt-target = { version = "0.3", features = ["cortex-m"] }
+embassy = { path = "../../embassy", features = ["defmt"] }
+embassy-stm32 = { path = "../../embassy-stm32", features = ["defmt", "stm32f030f4"] }
+
+[features]
+default = [
+    "defmt-default",
+]
+defmt-default = []
+defmt-trace = []
+defmt-debug = []
+defmt-info = []
+defmt-warn = []
+defmt-error = []

examples/stm32f0/build.rs

@@ -0,0 +1,31 @@
+//! This build script copies the `memory.x` file from the crate root into
+//! a directory where the linker can always find it at build time.
+//! For many projects this is optional, as the linker always searches the
+//! project root directory -- wherever `Cargo.toml` is. However, if you
+//! are using a workspace or have a more complicated build setup, this
+//! build script becomes required. Additionally, by requesting that
+//! Cargo re-run the build script whenever `memory.x` is changed,
+//! updating `memory.x` ensures a rebuild of the application with the
+//! new memory settings.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+}

examples/stm32f0/memory.x

@@ -0,0 +1,6 @@
+MEMORY
+{
+  FLASH : ORIGIN = 0x08000000, LENGTH = 16K
+  /* DTCM  */
+  RAM : ORIGIN = 0x20000000, LENGTH = 4K
+}

examples/stm32f0/src/bin/hello.rs

@@ -0,0 +1,23 @@
+#![no_std]
+#![no_main]
+#![feature(min_type_alias_impl_trait)]
+#![feature(impl_trait_in_bindings)]
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+use defmt::info;
+
+use embassy::executor::Spawner;
+use embassy::time::{Duration, Timer};
+use embassy_stm32::Peripherals;
+
+#[path = "../example_common.rs"]
+mod example_common;
+
+#[embassy::main]
+async fn main(_spawner: Spawner, _p: Peripherals) -> ! {
+    loop {
+        Timer::after(Duration::from_secs(1)).await;
+        info!("Hello");
+    }
+}

examples/stm32f0/src/example_common.rs

@@ -0,0 +1,17 @@
+#![macro_use]
+
+use defmt_rtt as _; // global logger
+use panic_probe as _;
+
+pub use defmt::*;
+
+use core::sync::atomic::{AtomicUsize, Ordering};
+
+defmt::timestamp! {"{=u64}", {
+        static COUNT: AtomicUsize = AtomicUsize::new(0);
+        // NOTE(no-CAS) `timestamps` runs with interrupts disabled
+        let n = COUNT.load(Ordering::Relaxed);
+        COUNT.store(n + 1, Ordering::Relaxed);
+        n as u64
+    }
+}