feat(example): add a USB HID keyboard example

examples/embassy-usb-keyboard/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "embassy-usb-keyboard"
+version = "0.1.0"
+authors.workspace = true
+edition.workspace = true
+publish = false
+
+[dependencies]
+riot-rs = { path = "../../src/riot-rs", features = ["time", "usb"] }
+riot-rs-boards = { path = "../../src/riot-rs-boards" }
+embassy-executor = { workspace = true, default-features = false }
+embassy-nrf = { workspace = true, default-features = false }
+embassy-sync = { workspace = true }
+embassy-usb = { workspace = true, features = ["usbd-hid"] }
+embassy-time = { workspace = true, default-features = false }
+static_cell = { workspace = true }
+usbd-hid = { version = "0.6.1"}

examples/embassy-usb-keyboard/README.md

@@ -0,0 +1,16 @@
+# embassy-usb-keyboard
+
+## About
+
+This application is testing basic
+[embassy](https://github.com/embassy-rs/embassy) _USB HID_ usage with RIOT-rs.
+
+## How to run
+
+In this folder, run
+
+    laze build -b nrf52840dk run
+
+With the device USB cable connected, pressing Button 1 should send the keycode
+0x04 ('a') to the connected computer, and pressing Button 2 should send keycode
+0x05 ('b').

examples/embassy-usb-keyboard/laze.yml

@@ -0,0 +1,5 @@
+apps:
+  - name: embassy-usb-keyboard
+    context: nrf52840dk
+    selects:
+      - ?release

examples/embassy-usb-keyboard/src/main.rs

@@ -0,0 +1,135 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+#![feature(used_with_arg)]
+
+use embassy_time::Duration;
+use embassy_usb::class::hid::{self, HidReaderWriter};
+use riot_rs::embassy::{make_static, UsbDriver};
+use riot_rs::linkme::distributed_slice;
+use riot_rs::rt::debug::println;
+
+use usbd_hid::descriptor::KeyboardReport;
+
+mod pins;
+
+// TODO: wrap in macro
+use riot_rs::embassy::delegate::Delegate;
+static USB_BUILDER_HOOK: Delegate<riot_rs::embassy::UsbBuilder> = Delegate::new();
+
+#[distributed_slice(riot_rs::embassy::USB_BUILDER_HOOKS)]
+#[linkme(crate=riot_rs::embassy::linkme)]
+static _USB_BUILDER_HOOK: &Delegate<riot_rs::embassy::UsbBuilder> = &USB_BUILDER_HOOK;
+
+#[embassy_executor::task]
+async fn usb_keyboard(button_peripherals: pins::Buttons) {
+    let mut buttons = Buttons::new(button_peripherals);
+
+    let config = embassy_usb::class::hid::Config {
+            report_descriptor: <usbd_hid::descriptor::KeyboardReport as usbd_hid::descriptor::SerializedDescriptor>::desc(),
+            request_handler: None,
+            poll_ms: 60,
+            max_packet_size: 64,
+        };
+
+    let hid_state = make_static!(hid::State::new());
+    let hid_rw: HidReaderWriter<'static, UsbDriver, 1, 8> = USB_BUILDER_HOOK
+        .with(|usb_builder| hid::HidReaderWriter::new(usb_builder, hid_state, config))
+        .await;
+
+    let (_hid_reader, mut hid_writer) = hid_rw.split();
+
+    loop {
+        for (i, button) in buttons.get_mut().iter_mut().enumerate() {
+            if button.is_pressed() {
+                println!("Button #{} pressed", i + 1);
+
+                let report = keyboard_report(KEYCODE_MAPPING[i]);
+                if let Err(e) = hid_writer.write_serialize(&report).await {
+                    println!("Failed to send report: {:?}", e);
+                }
+                let report = keyboard_report(KEY_RELEASED);
+                if let Err(e) = hid_writer.write_serialize(&report).await {
+                    println!("Failed to send report: {:?}", e);
+                }
+            }
+        }
+
+        // Debounce events
+        embassy_time::Timer::after(Duration::from_millis(50)).await;
+    }
+}
+
+// TODO: macro up this
+use riot_rs::embassy::{arch::OptionalPeripherals, Spawner};
+#[riot_rs::embassy::distributed_slice(riot_rs::embassy::EMBASSY_TASKS)]
+#[linkme(crate = riot_rs::embassy::linkme)]
+fn __init_usb_keyboard(spawner: &Spawner, peripherals: &mut OptionalPeripherals) {
+    spawner
+        .spawn(usb_keyboard(pins::Buttons::take_from(peripherals).unwrap()))
+        .unwrap();
+}
+
+use crate::buttons::{Buttons, KEY_COUNT};
+
+// Assuming a QWERTY US layout, see https://docs.qmk.fm/#/how_keyboards_work
+// and https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf
+const KC_A: u8 = 0x04;
+const KC_C: u8 = 0x06;
+const KC_G: u8 = 0x0a;
+const KC_T: u8 = 0x17;
+
+const KEY_RELEASED: u8 = 0x00;
+
+fn keyboard_report(keycode: u8) -> KeyboardReport {
+    KeyboardReport {
+        keycodes: [keycode, 0, 0, 0, 0, 0],
+        leds: 0,
+        modifier: 0,
+        reserved: 0,
+    }
+}
+
+// Maps physical buttons to keycodes/characters
+const KEYCODE_MAPPING: [u8; KEY_COUNT as usize] = [KC_A, KC_C, KC_G, KC_T];
+
+mod buttons {
+    use embassy_nrf::gpio::{AnyPin, Input, Pin, Pull};
+
+    use crate::pins;
+
+    pub const KEY_COUNT: u8 = 4;
+
+    pub struct Button(Input<'static>);
+
+    impl Button {
+        pub fn new(button: AnyPin) -> Self {
+            Self(Input::new(button, Pull::Up))
+        }
+
+        pub fn is_pressed(&mut self) -> bool {
+            self.0.is_low()
+        }
+    }
+
+    pub struct Buttons([Button; KEY_COUNT as usize]);
+
+    impl Buttons {
+        pub fn new(button_peripherals: pins::Buttons) -> Self {
+            Self([
+                Button::new(button_peripherals.btn1.degrade()),
+                Button::new(button_peripherals.btn2.degrade()),
+                Button::new(button_peripherals.btn3.degrade()),
+                Button::new(button_peripherals.btn4.degrade()),
+            ])
+        }
+
+        pub fn get(&self) -> &[Button] {
+            &self.0
+        }
+
+        pub fn get_mut(&mut self) -> &mut [Button] {
+            &mut self.0
+        }
+    }
+}

examples/embassy-usb-keyboard/src/pins.rs

@@ -0,0 +1,12 @@
+use embassy_nrf::peripherals;
+use riot_rs::define_peripherals;
+
+#[cfg(builder = "nrf52840dk")]
+define_peripherals! {
+    Buttons {
+        btn1: P0_11,
+        btn2: P0_12,
+        btn3: P0_24,
+        btn4: P0_25,
+    }
+}

examples/laze.yml

@@ -12,6 +12,7 @@ subdirs:
   - embassy-net-tcp
   - embassy-net-udp
     #  - embassy-gpio
+  - embassy-usb-keyboard
   - hello-world
   - minimal
   - riot-app