refactor: LoRaBoard trait with full associated types + BoardParts

- LoRaBoard trait now has associated types: RadioParts, CommParts, DisplayParts, DisplayDriver
- into_parts() is on the trait (enforced by compiler, not implicit convention)
- BoardParts<R, C, D> struct replaces tuple return from into_parts()
- mac_address() stays on trait, MAC also in BoardParts for convenience
- Removed mac field from DisplayParts (display task calls Board::mac_address())
- DisplayDriver associated type requires DrawTarget<Color = BinaryColor>

firmware/src/board/esp32s3.rs

@@ -44,7 +44,6 @@ pub struct UartParts {
 
 pub struct DisplayParts {
     pub i2c: DisplayI2c,
-    pub mac: [u8; 6],
 }
 
 // ── Display driver ──────────────────────────────────────────────────

firmware/src/board/heltec_v3.rs

@@ -1,17 +1,15 @@
 use esp_hal::gpio::{Level, Output, OutputConfig};
 
 use super::esp32s3;
-use super::traits::LoRaBoard;
+use super::traits::{BoardParts, LoRaBoard};
 use crate::hal::esp32s3 as mcu;
 
-#[allow(unused_imports)] // Re-exported for other modules (display, radio, uart tasks)
+#[allow(unused_imports)] // Re-exported for other modules (display, radio, host tasks)
 pub use super::esp32s3::{
     create_display, DisplayDriver, DisplayI2c, DisplayParts, RadioDriver, RadioParts, UartDriver,
     UartParts,
 };
 
-// ── Board init ──────────────────────────────────────────────────────
-
 pub struct Board {
     p: esp_hal::peripherals::Peripherals,
 }
@@ -20,6 +18,11 @@ impl LoRaBoard for Board {
     const NAME: &'static str = "Heltec V3";
     const TX_POWER_RANGE: (i8, i8) = (-9, 22);
 
+    type RadioParts = RadioParts;
+    type CommParts = UartParts;
+    type DisplayParts = DisplayParts;
+    type DisplayDriver = DisplayDriver;
+
     fn init() -> Self {
         let p = esp_hal::init(esp_hal::Config::default());
         Self { p }
@@ -28,21 +31,19 @@ impl LoRaBoard for Board {
     fn mac_address() -> [u8; 6] {
         mcu::mac_address()
     }
-}
 
-impl Board {
+    fn into_parts(self) -> BoardParts<RadioParts, UartParts, DisplayParts> {
-    pub fn into_parts(self) -> (RadioParts, UartParts, Option<DisplayParts>) {
         let p = self.p;
 
         mcu::start_timer(p.TIMG0);
 
         // Vext power: GPIO36, active LOW to enable peripherals
         let vext = Output::new(p.GPIO36, Level::Low, OutputConfig::default());
-        core::mem::forget(vext); // hold pin low permanently; drop would reset it
+        core::mem::forget(vext);
 
         let spi_bus = mcu::init_spi(p.SPI2, p.DMA_CH0, p.GPIO9, p.GPIO10, p.GPIO11);
         let radio = esp32s3::init_radio(spi_bus, p.GPIO8, p.GPIO12, p.GPIO14, p.GPIO13);
-        let uart = UartParts {
+        let host = UartParts {
             driver: mcu::init_uart(p.UART0, p.GPIO43, p.GPIO44),
         };
 
@@ -51,12 +52,16 @@ impl Board {
         esp_hal::delay::Delay::new().delay_millis(10);
         display_rst.set_high();
         esp_hal::delay::Delay::new().delay_millis(10);
-        core::mem::forget(display_rst); // hold reset high permanently
+        core::mem::forget(display_rst);
 
         let i2c = mcu::init_i2c(p.I2C0, p.GPIO17, p.GPIO18);
-        let mac = Self::mac_address();
+        let display = Some(DisplayParts { i2c });
-        let display = Some(DisplayParts { i2c, mac });
 
-        (radio, uart, display)
+        BoardParts {
+            radio,
+            host,
+            display,
+            mac: Self::mac_address(),
+        }
     }
 }

firmware/src/board/heltec_v4.rs

@@ -1,17 +1,15 @@
 use esp_hal::gpio::{Level, Output, OutputConfig};
 
 use super::esp32s3;
-use super::traits::LoRaBoard;
+use super::traits::{BoardParts, LoRaBoard};
 use crate::hal::esp32s3 as mcu;
 
-#[allow(unused_imports)] // Re-exported for other modules (display, radio, usb tasks)
+#[allow(unused_imports)] // Re-exported for other modules (display, radio, host tasks)
 pub use super::esp32s3::{
     create_display, DisplayDriver, DisplayI2c, DisplayParts, RadioDriver, RadioParts, UsbDriver,
     UsbParts,
 };
 
-// ── Board implementation ────────────────────────────────────────────
-
 pub struct Board {
     p: esp_hal::peripherals::Peripherals,
 }
@@ -20,6 +18,11 @@ impl LoRaBoard for Board {
     const NAME: &'static str = "Heltec V4";
     const TX_POWER_RANGE: (i8, i8) = (-9, 22);
 
+    type RadioParts = RadioParts;
+    type CommParts = UsbParts;
+    type DisplayParts = DisplayParts;
+    type DisplayDriver = DisplayDriver;
+
     fn init() -> Self {
         let p = esp_hal::init(esp_hal::Config::default());
         Self { p }
@@ -28,24 +31,21 @@ impl LoRaBoard for Board {
     fn mac_address() -> [u8; 6] {
         mcu::mac_address()
     }
-}
 
-impl Board {
+    fn into_parts(self) -> BoardParts<RadioParts, UsbParts, DisplayParts> {
-    pub fn into_parts(self) -> (RadioParts, UsbParts, Option<DisplayParts>) {
         let p = self.p;
 
         mcu::start_timer(p.TIMG0);
 
         // Vext power: GPIO36, active LOW to enable peripherals
         let vext = Output::new(p.GPIO36, Level::Low, OutputConfig::default());
-        core::mem::forget(vext); // hold pin low permanently; drop would reset it
+        core::mem::forget(vext);
 
         let spi_bus = mcu::init_spi(p.SPI2, p.DMA_CH0, p.GPIO9, p.GPIO10, p.GPIO11);
         let radio = esp32s3::init_radio(spi_bus, p.GPIO8, p.GPIO12, p.GPIO14, p.GPIO13);
 
         // Note: switches internal USB PHY from Serial-JTAG to OTG.
-        // espflash --monitor will stop working after this point.
+        let host = UsbParts {
-        let usb = UsbParts {
             driver: mcu::init_usb(p.USB0, p.GPIO20, p.GPIO19),
         };
 
@@ -54,12 +54,16 @@ impl Board {
         esp_hal::delay::Delay::new().delay_millis(10);
         display_rst.set_high();
         esp_hal::delay::Delay::new().delay_millis(10);
-        core::mem::forget(display_rst); // hold reset high permanently
+        core::mem::forget(display_rst);
 
         let i2c = mcu::init_i2c(p.I2C0, p.GPIO17, p.GPIO18);
-        let mac = Self::mac_address();
+        let display = Some(DisplayParts { i2c });
-        let display = Some(DisplayParts { i2c, mac });
 
-        (radio, usb, display)
+        BoardParts {
+            radio,
+            host,
+            display,
+            mac: Self::mac_address(),
+        }
     }
 }

firmware/src/board/rak_wisblock_4631.rs

@@ -9,7 +9,7 @@ use embassy_time::Delay;
 use lora_phy::iv::GenericSx126xInterfaceVariant;
 use lora_phy::sx126x::{self, Sx1262, Sx126x};
 
-use super::traits::LoRaBoard;
+use super::traits::{BoardParts, LoRaBoard};
 use crate::hal::nrf52840 as mcu;
 
 // ── Concrete peripheral types ───────────────────────────────────────
@@ -27,6 +27,23 @@ pub type DisplayDriver = ssd1306::Ssd1306Async<
     ssd1306::mode::BufferedGraphicsModeAsync<ssd1306::size::DisplaySize128x64>,
 >;
 
+// ── Peripheral bundles ──────────────────────────────────────────────
+
+pub struct RadioParts {
+    pub driver: RadioDriver,
+    pub delay: Delay,
+}
+
+pub struct UsbParts {
+    pub driver: UsbDriver,
+}
+
+pub struct DisplayParts {
+    pub i2c: DisplayI2c,
+}
+
+// ── Display init ────────────────────────────────────────────────────
+
 pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
     use ssd1306::mode::DisplayConfigAsync;
     use ssd1306::prelude::{Brightness, DisplayRotation};
@@ -46,22 +63,6 @@ pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
     Some(display)
 }
 
-// ── Peripheral bundles ──────────────────────────────────────────────
-
-pub struct RadioParts {
-    pub driver: RadioDriver,
-    pub delay: Delay,
-}
-
-pub struct UsbParts {
-    pub driver: UsbDriver,
-}
-
-pub struct DisplayParts {
-    pub i2c: DisplayI2c,
-    pub mac: [u8; 6],
-}
-
 // ── Board init ──────────────────────────────────────────────────────
 
 pub struct Board {
@@ -72,6 +73,11 @@ impl LoRaBoard for Board {
     const NAME: &'static str = "RAK WisBlock 4631";
     const TX_POWER_RANGE: (i8, i8) = (-9, 22);
 
+    type RadioParts = RadioParts;
+    type CommParts = UsbParts;
+    type DisplayParts = DisplayParts;
+    type DisplayDriver = DisplayDriver;
+
     fn init() -> Self {
         let p = embassy_nrf::init(Default::default());
         Self { p }
@@ -80,10 +86,8 @@ impl LoRaBoard for Board {
     fn mac_address() -> [u8; 6] {
         mcu::mac_address()
     }
-}
 
-impl Board {
+    fn into_parts(self) -> BoardParts<RadioParts, UsbParts, DisplayParts> {
-    pub fn into_parts(self) -> (RadioParts, UsbParts, Option<DisplayParts>) {
         let p = self.p;
 
         // ── SPI bus for SX1262 ──────────────────────────────────
@@ -95,7 +99,6 @@ impl Board {
         let nss = Output::new(p.P1_10, Level::High, OutputDrive::Standard);
         let spi_device = SpiDevice::new(spi_bus, nss);
 
-        // ── SX1262 control pins ─────────────────────────────────
         let reset = Output::new(p.P1_06, Level::High, OutputDrive::Standard);
         let dio1 = Input::new(p.P1_15, Pull::Down);
         let busy = Input::new(p.P1_14, Pull::Down);
@@ -117,7 +120,7 @@ impl Board {
 
         // ── USB ─────────────────────────────────────────────────
         let vbus = mcu::alloc_vbus_detect(true, false);
-        let usb = UsbParts {
+        let host = UsbParts {
             driver: Driver::new(p.USBD, mcu::Irqs, vbus),
         };
 
@@ -126,9 +129,13 @@ impl Board {
         let i2c = embassy_nrf::twim::Twim::new(
             p.TWISPI0, mcu::Irqs, p.P0_13, p.P0_14, twim::Config::default(), twim_buf,
         );
-        let mac = Self::mac_address();
+        let display = Some(DisplayParts { i2c });
-        let display = Some(DisplayParts { i2c, mac });
 
-        (radio, usb, display)
+        BoardParts {
+            radio,
+            host,
+            display,
+            mac: Self::mac_address(),
+        }
     }
 }

firmware/src/board/traits.rs

@@ -1,31 +1,48 @@
 //! Board abstraction trait.
 //!
-//! Every board must implement [`LoRaBoard`]. The compiler enforces completeness —
+//! Every board must implement [`LoRaBoard`] with concrete associated types
-//! missing constants or methods are compile errors, not runtime surprises.
+//! for its radio, host communication, and display peripherals. The compiler
-//!
+//! enforces completeness — missing types or methods are compile errors.
-//! Board modules also export concrete types (`RadioParts`, `UsbParts`,
-//! `DisplayParts`, `RadioDriver`, `UsbDriver`, `DisplayI2c`) that the tasks
-//! use directly. The trait verifies metadata and initialization; the types
-//! verify hardware compatibility.
 //!
 //! See `src/board/PORTING.md` for a step-by-step guide to adding a new board.
 
+use embedded_graphics::draw_target::DrawTarget;
+use embedded_graphics::pixelcolor::BinaryColor;
+
 /// Compile-time contract for a DongLoRa board.
-///
+pub trait LoRaBoard: Sized {
-/// Every board's `Board` struct must implement this trait. It verifies that
-/// the board provides all required metadata and initialization methods.
-/// The tasks use the board's concrete types directly (not the trait's
-/// associated types) because Embassy tasks must be concrete.
-pub trait LoRaBoard {
     /// Human-readable board name (shown on display splash screen).
     const NAME: &'static str;
 
     /// TX power range in dBm (min, max) for this board's radio + PA.
     const TX_POWER_RANGE: (i8, i8);
 
+    /// Radio peripheral bundle (driver + delay).
+    type RadioParts;
+
+    /// Host communication peripheral bundle (USB or UART driver).
+    type CommParts;
+
+    /// Display peripheral bundle (I2C bus for display init).
+    type DisplayParts;
+
+    /// Concrete display driver type (must implement DrawTarget for rendering).
+    type DisplayDriver: DrawTarget<Color = BinaryColor>;
+
     /// Initialize the board hardware.
     fn init() -> Self;
 
     /// Read the board's unique hardware address (MAC, device ID, etc.).
     fn mac_address() -> [u8; 6];
+
+    /// Decompose initialized board into peripheral bundles for each task.
+    fn into_parts(self) -> BoardParts<Self::RadioParts, Self::CommParts, Self::DisplayParts>;
+}
+
+/// Peripheral bundles for each firmware task, produced by [`LoRaBoard::into_parts`].
+pub struct BoardParts<R, C, D> {
+    pub radio: R,
+    pub host: C,
+    pub display: Option<D>,
+    pub mac: [u8; 6],
 }

firmware/src/board/wio_tracker_l1.rs

@@ -9,7 +9,7 @@ use embassy_time::Delay;
 use lora_phy::iv::GenericSx126xInterfaceVariant;
 use lora_phy::sx126x::{self, Sx1262, Sx126x};
 
-use super::traits::LoRaBoard;
+use super::traits::{BoardParts, LoRaBoard};
 use crate::hal::nrf52840 as mcu;
 
 // ── Concrete peripheral types ───────────────────────────────────────
@@ -23,18 +23,6 @@ pub type DisplayI2c = mcu::I2cBus;
 
 pub type DisplayDriver = crate::driver::sh1106::Sh1106<DisplayI2c>;
 
-pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
-    let mut display = crate::driver::sh1106::Sh1106::new(i2c, 0x3D);
-
-    embassy_time::Timer::after_millis(100).await;
-    if display.init().await.is_err() {
-        defmt::error!("SH1106 display init failed");
-        return None;
-    }
-    let _ = display.set_brightness(0xFF).await;
-    Some(display)
-}
-
 // ── Peripheral bundles ──────────────────────────────────────────────
 
 pub struct RadioParts {
@@ -48,7 +36,20 @@ pub struct UsbParts {
 
 pub struct DisplayParts {
     pub i2c: DisplayI2c,
-    pub mac: [u8; 6],
+}
+
+// ── Display init ────────────────────────────────────────────────────
+
+pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
+    let mut display = crate::driver::sh1106::Sh1106::new(i2c, 0x3D);
+
+    embassy_time::Timer::after_millis(100).await;
+    if display.init().await.is_err() {
+        defmt::error!("SH1106 display init failed");
+        return None;
+    }
+    let _ = display.set_brightness(0xFF).await;
+    Some(display)
 }
 
 // ── Board init ──────────────────────────────────────────────────────
@@ -61,6 +62,11 @@ impl LoRaBoard for Board {
     const NAME: &'static str = "Wio Tracker L1";
     const TX_POWER_RANGE: (i8, i8) = (-9, 22);
 
+    type RadioParts = RadioParts;
+    type CommParts = UsbParts;
+    type DisplayParts = DisplayParts;
+    type DisplayDriver = DisplayDriver;
+
     fn init() -> Self {
         let mut config = embassy_nrf::config::Config::default();
         config.hfclk_source = embassy_nrf::config::HfclkSource::ExternalXtal;
@@ -72,10 +78,8 @@ impl LoRaBoard for Board {
     fn mac_address() -> [u8; 6] {
         mcu::mac_address()
     }
-}
 
-impl Board {
+    fn into_parts(self) -> BoardParts<RadioParts, UsbParts, DisplayParts> {
-    pub fn into_parts(self) -> (RadioParts, UsbParts, Option<DisplayParts>) {
         let p = self.p;
 
         // ── SPI bus for SX1262 ──────────────────────────────────
@@ -87,7 +91,6 @@ impl Board {
         let nss = Output::new(p.P1_14, Level::High, OutputDrive::Standard);
         let spi_device = SpiDevice::new(spi_bus, nss);
 
-        // ── SX1262 control pins ─────────────────────────────────
         let reset = Output::new(p.P1_07, Level::High, OutputDrive::Standard);
         let dio1 = Input::new(p.P0_07, Pull::Down);
         let busy = Input::new(p.P1_10, Pull::Down);
@@ -111,7 +114,7 @@ impl Board {
 
         // ── USB ─────────────────────────────────────────────────
         let vbus = mcu::alloc_vbus_detect(true, true);
-        let usb = UsbParts {
+        let host = UsbParts {
             driver: Driver::new(p.USBD, mcu::Irqs, vbus),
         };
 
@@ -124,9 +127,13 @@ impl Board {
         let i2c = embassy_nrf::twim::Twim::new(
             p.TWISPI0, mcu::Irqs, p.P0_06, p.P0_05, twim::Config::default(), twim_buf,
         );
-        let mac = Self::mac_address();
+        let display = Some(DisplayParts { i2c });
-        let display = Some(DisplayParts { i2c, mac });
 
-        (radio, usb, display)
+        BoardParts {
+            radio,
+            host,
+            display,
+            mac: Self::mac_address(),
+        }
     }
 }

firmware/src/display.rs

@@ -108,7 +108,7 @@ pub async fn display_task(
 ) {
     // Format MAC address as "XX:XX:XX:XX:XX:XX"
     let mut mac_str: heapless::String<18> = heapless::String::new();
-    let m = parts.mac;
+    let m = Board::mac_address();
     let _ = core::fmt::Write::write_fmt(
         &mut mac_str,
         format_args!(

firmware/src/main.rs

@@ -77,27 +77,24 @@ cfg_if::cfg_if! {
 #[cfg(not(test))]
 async fn run(spawner: Spawner) {
     let board = <board::Board as LoRaBoard>::init();
-    let mac = board::Board::mac_address();
+    let parts = board.into_parts();
-    let (radio, comm, display) = board.into_parts();
-
-    let has_display = display.is_some();
 
     spawner
-        .spawn(radio::radio_task(radio, &COMMANDS, &RESPONSES, &STATUS))
+        .spawn(radio::radio_task(parts.radio, &COMMANDS, &RESPONSES, &STATUS))
         .expect("spawn radio_task");
 
     spawner
         .spawn(host::host_task(
-            comm,
+            parts.host,
             &COMMANDS,
             &RESPONSES,
             &DISPLAY_COMMANDS,
-            has_display,
+            parts.display.is_some(),
-            mac,
+            parts.mac,
         ))
         .expect("spawn host_task");
 
-    if let Some(dp) = display {
+    if let Some(dp) = parts.display {
         spawner
             .spawn(display::display_task(dp, &STATUS, &DISPLAY_COMMANDS))
             .expect("spawn display_task");