refactor: extract hal/ and driver/ modules

- Created hal/esp32s3.rs with MCU primitives (SPI, I2C, USB, UART, timer, MAC)
- Created hal/nrf52840.rs with shared nRF boilerplate (interrupts, bus wrapping, VBUS, MAC)
- Moved SH1106 OLED driver from display/ to driver/ (clear separation from app code)
- Board esp32s3.rs now delegates MCU init to hal, keeps only peripheral wiring (RadioParts)
- nRF board files use hal for shared StaticCell patterns, mac_address, interrupt bindings
- Board files still own pin assignments and peripheral construction

src/board/wio_tracker_l1.rs

@@ -1,40 +1,27 @@
 use embassy_embedded_hal::shared_bus::asynch::spi::SpiDevice;
 use embassy_nrf::gpio::{Input, Level, Output, OutputDrive, Pull};
 use embassy_nrf::spim::{self, Spim};
-use embassy_nrf::twim::{self, Twim};
+use embassy_nrf::twim;
 use embassy_nrf::usb::Driver;
-use embassy_nrf::{bind_interrupts, Peripherals};
 use embassy_sync::blocking_mutex::raw::NoopRawMutex;
 use embassy_time::Delay;
-use static_cell::StaticCell;
 
 use lora_phy::iv::GenericSx126xInterfaceVariant;
 use lora_phy::sx126x::{self, Sx1262, Sx126x};
 
 use super::traits::LoRaBoard;
+use crate::hal::nrf52840 as mcu;
 
-bind_interrupts!(struct Irqs {
-    USBD => embassy_nrf::usb::InterruptHandler<embassy_nrf::peripherals::USBD>;
-    SPIM3 => embassy_nrf::spim::InterruptHandler<embassy_nrf::peripherals::SPI3>;
-    TWISPI0 => embassy_nrf::twim::InterruptHandler<embassy_nrf::peripherals::TWISPI0>;
-});
+// ── Concrete peripheral types ───────────────────────────────────────
 
-// ── Concrete peripheral types ────────────────────────────────────────
-
-type SpiBus = Spim<'static>;
 type Nss = Output<'static>;
 type Iv = GenericSx126xInterfaceVariant<Output<'static>, Input<'static>>;
-type RadioSpiDevice = SpiDevice<'static, NoopRawMutex, SpiBus, Nss>;
-/// SX126x driver (pre-LoRa construction — LoRa::new is async).
+type RadioSpiDevice = SpiDevice<'static, NoopRawMutex, mcu::SpiBus, Nss>;
 pub type RadioDriver = Sx126x<RadioSpiDevice, Iv, Sx1262>;
+pub type UsbDriver = mcu::UsbNrfDriver;
+pub type DisplayI2c = mcu::I2cBus;
 
-/// USB driver for CDC-ACM.
-pub type UsbDriver = Driver<'static, &'static embassy_nrf::usb::vbus_detect::SoftwareVbusDetect>;
-
-/// I2C bus for SH1106 OLED.
-pub type DisplayI2c = Twim<'static>;
-
-// ── Peripheral bundles ───────────────────────────────────────────────
+// ── Peripheral bundles ──────────────────────────────────────────────
 
 pub struct RadioParts {
     pub driver: RadioDriver,
@@ -50,13 +37,13 @@ pub struct DisplayParts {
     pub mac: [u8; 6],
 }
 
-// ── Board init ───────────────────────────────────────────────────────
+// ── Board init ──────────────────────────────────────────────────────
 
 pub struct Board {
-    p: Peripherals,
+    p: embassy_nrf::Peripherals,
 }
 
-impl super::traits::LoRaBoard for Board {
+impl LoRaBoard for Board {
     const NAME: &'static str = "Wio Tracker L1";
     const TX_POWER_RANGE: (i8, i8) = (-9, 22);
 
@@ -69,23 +56,7 @@ impl super::traits::LoRaBoard for Board {
     }
 
     fn mac_address() -> [u8; 6] {
-        // SAFETY: 0x10000000 is the nRF52840 FICR (Factory Information Configuration
-        // Registers) base address. Offsets 0x0A4 and 0x0A8 are the DEVICEADDR[0] and
-        // DEVICEADDR[1] registers containing the factory-programmed device address.
-        // read_volatile is correct for memory-mapped hardware registers.
-        unsafe {
-            let ficr = 0x10000000 as *const u32;
-            let addr0 = core::ptr::read_volatile(ficr.byte_add(0x0A4));
-            let addr1 = core::ptr::read_volatile(ficr.byte_add(0x0A8));
-            [
-                addr0 as u8,
-                (addr0 >> 8) as u8,
-                (addr0 >> 16) as u8,
-                (addr0 >> 24) as u8,
-                addr1 as u8,
-                (addr1 >> 8) as u8,
-            ]
-        }
+        mcu::mac_address()
     }
 }
 
@@ -93,19 +64,16 @@ impl Board {
     pub fn into_parts(self) -> (RadioParts, UsbParts, Option<DisplayParts>) {
         let p = self.p;
 
-        // ── SPI bus for SX1262 ───────────────────────────────────
+        // ── SPI bus for SX1262 ──────────────────────────────────
         let mut spi_cfg = spim::Config::default();
         spi_cfg.frequency = spim::Frequency::M1;
-        let spi = Spim::new(p.SPI3, Irqs, p.P0_30, p.P0_03, p.P0_28, spi_cfg);
-
-        static SPI_BUS: StaticCell<embassy_sync::mutex::Mutex<NoopRawMutex, SpiBus>> =
-            StaticCell::new();
-        let spi_bus = SPI_BUS.init(embassy_sync::mutex::Mutex::new(spi));
+        let spi = Spim::new(p.SPI3, mcu::Irqs, p.P0_30, p.P0_03, p.P0_28, spi_cfg);
+        let spi_bus = mcu::share_spi_bus(spi);
 
         let nss = Output::new(p.P1_14, Level::High, OutputDrive::Standard);
         let spi_device = SpiDevice::new(spi_bus, nss);
 
-        // ── SX1262 control pins ──────────────────────────────────
+        // ── 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);
@@ -127,25 +95,21 @@ impl Board {
             delay: Delay,
         };
 
-        // ── USB ──────────────────────────────────────────────────
-        static VBUS: StaticCell<embassy_nrf::usb::vbus_detect::SoftwareVbusDetect> =
-            StaticCell::new();
-        let vbus = VBUS.init(embassy_nrf::usb::vbus_detect::SoftwareVbusDetect::new(
-            true, true,
-        ));
+        // ── USB ─────────────────────────────────────────────────
+        let vbus = mcu::alloc_vbus_detect(true, true);
         let usb = UsbParts {
-            driver: Driver::new(p.USBD, Irqs, vbus),
+            driver: Driver::new(p.USBD, mcu::Irqs, vbus),
         };
 
         // ── BAT_CTL: P0.04, active HIGH — enables power to OLED and battery sense
         let bat_ctl = Output::new(p.P0_04, Level::High, OutputDrive::Standard);
         core::mem::forget(bat_ctl);
 
-        // ── Display (SH1106 OLED on I2C) ─────────────────────────
-        static TWIM_BUF: StaticCell<[u8; 256]> = StaticCell::new();
-        let twim_buf = TWIM_BUF.init([0u8; 256]);
-        let i2c_cfg = twim::Config::default();
-        let i2c = Twim::new(p.TWISPI0, Irqs, p.P0_06, p.P0_05, i2c_cfg, twim_buf);
+        // ── Display (SH1106 OLED on I2C) ────────────────────────
+        let twim_buf = mcu::alloc_i2c_buffer();
+        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, mac });