init basic examples and setup

examples/README.md

@@ -0,0 +1,38 @@
+# Examples
+
+Each example is its own Cargo package.
+
+## Packages
+
+- `blinky-basic` - simple delay, simple LED ownership story
+- `blinky-timer` - periodic blink with a timer abstraction
+- `button-input` - poll `PA0`, mirror state to `PC13`, log transitions
+- `embassy-blinky` - minimal Embassy executor and async blink
+- `embassy-button` - minimal Embassy polling loop for `PA0`
+
+## Build One Example
+
+```bash
+just build-blinky
+just build-timer
+just build-button
+just build-embassy-blinky
+just build-embassy-button
+```
+
+## Flash One Example
+
+```bash
+just flash-blinky
+just flash-timer
+just flash-button
+just flash-embassy-blinky
+just flash-embassy-button
+```
+
+## Run With Logs
+
+```bash
+just run-blinky
+just run-embassy-blinky
+```

examples/blinky-basic/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "blinky-basic"
+version = "0.1.0"
+edition = "2024"
+publish = false
+build = "build.rs"
+
+[dependencies]
+cortex-m.workspace = true
+cortex-m-rt.workspace = true
+defmt.workspace = true
+defmt-rtt.workspace = true
+panic-probe.workspace = true
+stm32f1xx-hal = { workspace = true, features = ["medium", "stm32f103"] }

examples/blinky-basic/build.rs

@@ -0,0 +1,9 @@
+fn main() {
+    println!("cargo:rerun-if-changed=../../memory.x");
+    println!(
+        "cargo:rustc-link-search={}",
+        std::path::PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap())
+            .join("../..")
+            .display()
+    );
+}

examples/blinky-basic/src/main.rs

@@ -0,0 +1,37 @@
+#![deny(unsafe_code)]
+#![no_std]
+#![no_main]
+
+use cortex_m_rt::entry;
+use defmt::info;
+use defmt_rtt as _;
+use panic_probe as _;
+use stm32f1xx_hal::{pac, prelude::*};
+
+const ON_MS: u16 = 500;
+const OFF_MS: u16 = 500;
+
+#[entry]
+fn main() -> ! {
+    let dp = pac::Peripherals::take().unwrap();
+    let cp = cortex_m::Peripherals::take().unwrap();
+
+    let mut rcc = dp.RCC.constrain();
+    let mut gpioc = dp.GPIOC.split(&mut rcc);
+
+    // Splitting the GPIO block gives this function ownership of the LED pin.
+    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
+    let mut delay = cp.SYST.delay(&rcc.clocks);
+
+    info!("blinky-basic: PC13 LED is assumed active-low");
+
+    loop {
+        led.set_low();
+        info!("led on");
+        delay.delay_ms(ON_MS);
+
+        led.set_high();
+        info!("led off");
+        delay.delay_ms(OFF_MS);
+    }
+}

examples/blinky-timer/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "blinky-timer"
+version = "0.1.0"
+edition = "2024"
+publish = false
+build = "build.rs"
+
+[dependencies]
+cortex-m.workspace = true
+cortex-m-rt.workspace = true
+defmt.workspace = true
+defmt-rtt.workspace = true
+nb.workspace = true
+panic-probe.workspace = true
+stm32f1xx-hal = { workspace = true, features = ["medium", "stm32f103"] }

examples/blinky-timer/build.rs

@@ -0,0 +1,9 @@
+fn main() {
+    println!("cargo:rerun-if-changed=../../memory.x");
+    println!(
+        "cargo:rustc-link-search={}",
+        std::path::PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap())
+            .join("../..")
+            .display()
+    );
+}

examples/blinky-timer/src/main.rs

@@ -0,0 +1,35 @@
+#![deny(unsafe_code)]
+#![no_std]
+#![no_main]
+
+use cortex_m_rt::entry;
+use defmt::info;
+use defmt_rtt as _;
+use nb::block;
+use panic_probe as _;
+use stm32f1xx_hal::{pac, prelude::*, timer::Timer};
+
+const BLINK_HZ: u32 = 2;
+
+#[entry]
+fn main() -> ! {
+    let dp = pac::Peripherals::take().unwrap();
+    let cp = cortex_m::Peripherals::take().unwrap();
+
+    let mut rcc = dp.RCC.constrain();
+    let mut gpioc = dp.GPIOC.split(&mut rcc);
+    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
+
+    // A timer gives stable periodic work without burning cycles in a delay loop.
+    let mut timer = Timer::syst(cp.SYST, &rcc.clocks).counter_hz();
+    timer.start(BLINK_HZ.Hz()).unwrap();
+
+    led.set_high();
+    info!("blinky-timer: {} Hz toggle loop", BLINK_HZ);
+
+    loop {
+        block!(timer.wait()).unwrap();
+        led.toggle();
+        info!("tick");
+    }
+}

examples/button-input/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "button-input"
+version = "0.1.0"
+edition = "2024"
+publish = false
+build = "build.rs"
+
+[dependencies]
+cortex-m.workspace = true
+cortex-m-rt.workspace = true
+defmt.workspace = true
+defmt-rtt.workspace = true
+panic-probe.workspace = true
+stm32f1xx-hal = { workspace = true, features = ["medium", "stm32f103"] }

examples/button-input/build.rs

@@ -0,0 +1,9 @@
+fn main() {
+    println!("cargo:rerun-if-changed=../../memory.x");
+    println!(
+        "cargo:rustc-link-search={}",
+        std::path::PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap())
+            .join("../..")
+            .display()
+    );
+}

examples/button-input/src/main.rs

@@ -0,0 +1,47 @@
+#![deny(unsafe_code)]
+#![no_std]
+#![no_main]
+
+use cortex_m_rt::entry;
+use defmt::info;
+use defmt_rtt as _;
+use panic_probe as _;
+use stm32f1xx_hal::{pac, prelude::*};
+
+const POLL_MS: u8 = 25;
+
+#[entry]
+fn main() -> ! {
+    let dp = pac::Peripherals::take().unwrap();
+    let cp = cortex_m::Peripherals::take().unwrap();
+
+    let mut rcc = dp.RCC.constrain();
+    let mut gpioa = dp.GPIOA.split(&mut rcc);
+    let mut gpioc = dp.GPIOC.split(&mut rcc);
+
+    let button = gpioa.pa0.into_pull_down_input(&mut gpioa.crl);
+    let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
+    let mut delay = cp.SYST.delay(&rcc.clocks);
+    let mut was_pressed = button.is_high();
+
+    led.set_high();
+    info!("button-input: PA0 button to 3V3 with internal pull-down");
+
+    loop {
+        let pressed = button.is_high();
+
+        if pressed != was_pressed {
+            was_pressed = pressed;
+
+            if pressed {
+                led.set_low();
+                info!("button pressed");
+            } else {
+                led.set_high();
+                info!("button released");
+            }
+        }
+
+        delay.delay_ms(POLL_MS);
+    }
+}

examples/embassy-blinky/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "embassy-blinky"
+version = "0.1.0"
+edition = "2024"
+publish = false
+build = "build.rs"
+
+[dependencies]
+cortex-m-rt.workspace = true
+defmt.workspace = true
+defmt-rtt.workspace = true
+embassy-executor = { workspace = true, features = ["defmt", "executor-thread", "platform-cortex-m"] }
+embassy-stm32 = { workspace = true, features = ["defmt", "stm32f103c8", "time-driver-tim2"] }
+embassy-time.workspace = true
+panic-probe.workspace = true

examples/embassy-blinky/build.rs

@@ -0,0 +1,9 @@
+fn main() {
+    println!("cargo:rerun-if-changed=../../memory.x");
+    println!(
+        "cargo:rustc-link-search={}",
+        std::path::PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap())
+            .join("../..")
+            .display()
+    );
+}

examples/embassy-blinky/src/main.rs

@@ -0,0 +1,28 @@
+#![deny(unsafe_code)]
+#![no_std]
+#![no_main]
+
+use defmt::info;
+use defmt_rtt as _;
+use embassy_executor::Spawner;
+use embassy_stm32::gpio::{Level, Output, Speed};
+use embassy_time::Timer;
+use panic_probe as _;
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+    let mut led = Output::new(p.PC13, Level::High, Speed::Low);
+
+    info!("embassy-blinky: async blink on PC13");
+
+    loop {
+        led.set_low();
+        info!("led on");
+        Timer::after_millis(500).await;
+
+        led.set_high();
+        info!("led off");
+        Timer::after_millis(500).await;
+    }
+}

examples/embassy-button/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "embassy-button"
+version = "0.1.0"
+edition = "2024"
+publish = false
+build = "build.rs"
+
+[dependencies]
+cortex-m-rt.workspace = true
+defmt.workspace = true
+defmt-rtt.workspace = true
+embassy-executor = { workspace = true, features = ["defmt", "executor-thread", "platform-cortex-m"] }
+embassy-stm32 = { workspace = true, features = ["defmt", "stm32f103c8", "time-driver-tim2"] }
+embassy-time.workspace = true
+panic-probe.workspace = true

examples/embassy-button/build.rs

@@ -0,0 +1,9 @@
+fn main() {
+    println!("cargo:rerun-if-changed=../../memory.x");
+    println!(
+        "cargo:rustc-link-search={}",
+        std::path::PathBuf::from(std::env::var("CARGO_MANIFEST_DIR").unwrap())
+            .join("../..")
+            .display()
+    );
+}

examples/embassy-button/src/main.rs

@@ -0,0 +1,38 @@
+#![deny(unsafe_code)]
+#![no_std]
+#![no_main]
+
+use defmt::info;
+use defmt_rtt as _;
+use embassy_executor::Spawner;
+use embassy_stm32::gpio::{Input, Level, Output, Pull, Speed};
+use embassy_time::Timer;
+use panic_probe as _;
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+    let button = Input::new(p.PA0, Pull::Down);
+    let mut led = Output::new(p.PC13, Level::High, Speed::Low);
+    let mut was_pressed = button.is_high();
+
+    info!("embassy-button: polling PA0 every 25 ms");
+
+    loop {
+        let pressed = button.is_high();
+
+        if pressed != was_pressed {
+            was_pressed = pressed;
+
+            if pressed {
+                led.set_low();
+                info!("button pressed");
+            } else {
+                led.set_high();
+                info!("button released");
+            }
+        }
+
+        Timer::after_millis(25).await;
+    }
+}