add new hardware peripheral

examples/README.md

@@ -6,9 +6,9 @@ Each example is its own Cargo package.
 
 - `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
+- `button-input` - poll the center button on `PA8`, mirror state to `PC13`, log transitions
 - `embassy-blinky` - minimal Embassy executor and async blink
-- `embassy-button` - minimal Embassy polling loop for `PA0`
+- `embassy-button` - minimal Embassy polling loop for the center button on `PA8`
 
 ## Build One Example
 

examples/button-input/src/main.rs

@@ -17,18 +17,25 @@ fn main() -> ! {
 
     let mut rcc = dp.RCC.constrain();
     let mut gpioa = dp.GPIOA.split(&mut rcc);
+    let mut gpiob = dp.GPIOB.split(&mut rcc);
     let mut gpioc = dp.GPIOC.split(&mut rcc);
 
-    let button = gpioa.pa0.into_pull_down_input(&mut gpioa.crl);
+    // Assumes the center switch line goes high when pressed.
+    let button = gpioa.pa8.into_pull_down_input(&mut gpioa.crh);
+    let mut vcc = gpioa.pa10.into_push_pull_output(&mut gpioa.crh);
+    let mut gnd = gpiob.pb12.into_push_pull_output(&mut gpiob.crh);
     let mut led = gpioc.pc13.into_push_pull_output(&mut gpioc.crh);
     let mut delay = cp.SYST.delay(&rcc.clocks);
+
+    gnd.set_low();
+    vcc.set_high();
     let mut was_pressed = button.is_high();
 
     led.set_high();
-    info!("button-input: PA0 button to 3V3 with internal pull-down");
+    info!("button-input: PA8 center button, PA10 high, PB12 low");
 
     loop {
-        let pressed = button.is_high();
+        let pressed = !button.is_high();
 
         if pressed != was_pressed {
             was_pressed = pressed;

examples/embassy-blinky/Cargo.toml

@@ -6,6 +6,7 @@ publish = false
 build = "build.rs"
 
 [dependencies]
+cortex-m.workspace = true
 cortex-m-rt.workspace = true
 defmt.workspace = true
 defmt-rtt.workspace = true

examples/embassy-blinky/src/main.rs

@@ -4,6 +4,7 @@
 
 use defmt::info;
 use defmt_rtt as _;
+use cortex_m as _;
 use embassy_executor::Spawner;
 use embassy_stm32::gpio::{Level, Output, Speed};
 use embassy_time::Timer;

examples/embassy-button/Cargo.toml

@@ -6,6 +6,7 @@ publish = false
 build = "build.rs"
 
 [dependencies]
+cortex-m.workspace = true
 cortex-m-rt.workspace = true
 defmt.workspace = true
 defmt-rtt.workspace = true

examples/embassy-button/src/main.rs

@@ -4,6 +4,7 @@
 
 use defmt::info;
 use defmt_rtt as _;
+use cortex_m as _;
 use embassy_executor::Spawner;
 use embassy_stm32::gpio::{Input, Level, Output, Pull, Speed};
 use embassy_time::Timer;
@@ -12,14 +13,17 @@ 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);
+    // Assumes the center switch line goes high when pressed.
+    let button = Input::new(p.PA8, Pull::Down);
+    let _vcc = Output::new(p.PA10, Level::High, Speed::Low);
+    let _gnd = Output::new(p.PB12, Level::Low, Speed::Low);
     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");
+    info!("embassy-button: polling PA8 every 25 ms");
 
     loop {
-        let pressed = button.is_high();
+        let pressed = !button.is_high();
 
         if pressed != was_pressed {
             was_pressed = pressed;