add new hardware peripheral

Cargo.lock

@@ -296,6 +296,7 @@ dependencies = [
 name = "embassy-blinky"
 version = "0.1.0"
 dependencies = [
+ "cortex-m",
  "cortex-m-rt",
  "defmt 1.1.0",
  "defmt-rtt",
@@ -309,6 +310,7 @@ dependencies = [
 name = "embassy-button"
 version = "0.1.0"
 dependencies = [
+ "cortex-m",
  "cortex-m-rt",
  "defmt 1.1.0",
  "defmt-rtt",

README.md

@@ -11,6 +11,29 @@
 
 See [blue-pill.md](docs/hardware/blue-pill.md) for wiring notes.
 
+## Attached Hardware
+
+- internal LED: `PC13`
+- RGB LED:
+  - `PA5` = red
+  - `PA6` = green
+  - `PA7` = blue
+  - `PA4` = drive low for the LED return path
+- 5-way button board:
+  - `PB12` = GND, drive low
+  - `PA10` = VCC, drive high
+  - `PB13` = right
+  - `PB14` = down
+  - `PB15` = left
+  - `PA8` = center
+  - `PA9` = up
+- HMC5883L module:
+  - `PB4` = VCC, drive high
+  - `PB5` = GND, drive low
+  - `PB6` = SCL
+  - `PB7` = SDA
+  - `PB8` = DRDY
+
 ## Important Target Note
 
 - Blue Pill `STM32F103` is Cortex-M3 and uses `thumbv7m-none-eabi`.
@@ -71,14 +94,15 @@ probe-rs chip list | rg STM32F103
 
 - `blinky-basic` - plain `no_std` blink with a simple delay
 - `blinky-timer` - periodic blink driven by a timer abstraction
-- `button-input` - poll a button on `PA0`, mirror state on the LED, log transitions
+- `button-input` - poll the center button on `PA8`, mirror state on the LED, log transitions
 - `embassy-blinky` - minimal async blink with Embassy
-- `embassy-button` - minimal Embassy polling loop for a button on `PA0`
+- `embassy-button` - minimal Embassy polling loop for the center button on `PA8`
 
-The button examples assume a simple external button:
+The button examples assume the 5-way board is wired like this:
 
-- one side to `PA0`
-- one side to `3V3`
+- `PB12` forced low for ground
+- `PA10` forced high for power
+- `PA8` used as the center button input
 - internal pull-down enabled in firmware
 - common ground still required for the probe
 

docs/hardware/blue-pill.md

@@ -13,12 +13,33 @@
 - `set_low()` usually turns it on
 - `set_high()` usually turns it off
 
-## Button Assumption
+## RGB LED
 
-- The repo button examples use `PA0`
-- Assumed wiring:
-  - button between `PA0` and `3V3`
-  - firmware enables internal pull-down
+- `PA5` = red
+- `PA6` = green
+- `PA7` = blue
+- `PA4` = drive low for the LED return path
+
+## 5-Way Button Board
+
+- `PB12` = GND, drive low
+- `PA10` = VCC, drive high
+- `PB13` = right
+- `PB14` = down
+- `PB15` = left
+- `PA8` = center
+- `PA9` = up
+- Assumption: the button inputs read high when pressed
+- The button examples use `PA8` as the default center button
+- TODO: flip the input polarity if your module is active-low instead
+
+## HMC5883L Module
+
+- `PB4` = VCC, drive high
+- `PB5` = GND, drive low
+- `PB6` = SCL
+- `PB7` = SDA
+- `PB8` = DRDY
 
 ## Probe Wiring
 

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;

justfile

@@ -45,10 +45,22 @@ run-blinky:
     cargo build -p blinky-basic
     probe-rs run --chip {{chip}} target/{{target}}/debug/blinky-basic
 
+run-timer:
+    cargo build -p blinky-timer
+    probe-rs run --chip {{chip}} target/{{target}}/debug/blinky-timer
+
+run-button:
+    cargo build -p button-input
+    probe-rs run --chip {{chip}} target/{{target}}/debug/button-input
+
 run-embassy-blinky:
     cargo build -p embassy-blinky
     probe-rs run --chip {{chip}} target/{{target}}/debug/embassy-blinky
 
+run-embassy-button:
+    cargo build -p embassy-button
+    probe-rs run --chip {{chip}} target/{{target}}/debug/embassy-button
+
 fmt:
     cargo fmt --all