The Rmt struct was being dropped after extracting channel0, which
likely disabled the RMT peripheral. Use ManuallyDrop to keep it alive.
Also log WS2812 transmit errors instead of silently discarding them.
The Heltec V3 has a plain white LED on GPIO35 (simple GPIO, not
addressable). Only the V4 has a WS2812B RGB LED on GPIO38.
- Created driver/simple_led.rs for single-color GPIO LEDs
- V3/V3-UART boards: SimpleLed on GPIO35 (white blink on RX/TX)
- V4 board: unchanged (WS2812 on GPIO38, green/red colors)
- nRF boards: unchanged (no LED, type LedDriver = ())
- Added RgbLed trait with impl on () for boards without LED
- Added WS2812 driver (driver/ws2812.rs) using ESP32-S3 RMT peripheral
- 80MHz clock, 12.5ns resolution, 24-bit GRB encoding
- Zero extra crate dependencies
- Heltec V3/V3-UART/V4: WS2812B on GPIO38 via RMT channel 0
- RAK WisBlock/Wio Tracker: type LedDriver = (), led = None (no-op)
- Display task: green blink on RX packet, red blink on TX packet
- LED auto-off on timer tick (~1s), off when display is off/reset
- LoRaBoard trait gains type LedDriver: RgbLed associated type
- BoardParts gains led: Option<L> field
- heltec_v3 now uses USB OTG (requires hardware mod: solder R29/R3)
- heltec_v3_uart added as fallback for stock boards
- Removed every #[allow(dead_code)] — fixed root causes instead:
- Comm types (UsbParts/UartParts) moved to individual board files
- USB/UART init removed from hal (boards call esp-hal directly)
- SH1106 driver gated on boards that use it
- UART task sends DisplayCommand::Reset at startup (variant now used)
- ErrorCode::CrcError removed (SX1262 drops bad-CRC silently)
- check/clippy now use --release (no more Xtensa dev-mode warnings)
- Updated README with hardware mod docs and board table
- 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
swaits