feat(t114): add Heltec Mesh Node T114 board support

Adds nRF52840 + SX1262 + 1.14" 240×135 ST7789 color TFT support. First
color display board in the project; introduces a BoardDisplay trait so
each board renders to its native pixel format and resolution without
aliasing or color-quantization round-trips.

Architecture:
- New BoardDisplay trait (src/display.rs) bundles render_*, present(),
  set_bright/set_dim. Replaces the old DrawTarget<Color=BinaryColor>
  + DisplayBrightness combo as the LoRaBoard::DisplayDriver bound.
- Mono OLED drivers (Sh1106, Ssd1306Async) get adapter impls that
  delegate to the existing display::render module — no behavior change
  for any existing board.
- T114 ST7789 driver (src/driver/st7789.rs) wraps lcd-async (async fork
  of mipidsi) with a 64,800-byte raw byte framebuffer in .bss. Renders
  via lcd_async::raw_framebuf::RawFrameBuf<Rgb565, _>, presents via a
  single async DMA blit (panel.show_raw_data(...).await) — the await
  yields the executor for the ~65 ms SPI transfer so the radio task
  isn't starved during repaints.
- PWM backlight on PWM0 / P0.15 (active-LOW, inverted polarity) for
  smooth dim/bright transitions instead of GPIO toggle.
- Native 240×135 Rgb565 renderer (src/display/render_color.rs) with
  splash + dashboard + sparkline.
- Shared QR-code blit (src/display/qr.rs), generic over PixelColor,
  re-centers the 64×64 bitmap which has cells in cols 0..50 and ~14 px
  of right-side padding — both mono and color splash now show the QR
  with 7 px quiet zones on all four sides (was visibly left-shifted).
- Shared content types (BoardInfo, DashboardCtx) decouple what to draw
  from how each board renders it.
- create_display() now takes the board's full DisplayParts bundle
  (was just the I2C bus) so non-I2C displays can carry SPI + control
  pins through.

Hardware:
- VEXT_ENABLE on P0.21 driven HIGH at boot — powers the SX1262 + TFT
  rail. Without this, lora-phy init succeeds at the SPI level but
  TX_DONE never fires.
- VTFT_CTRL on P0.03, active LOW; backlight on P0.15, active LOW.
- TFT SPI2 (SCK P1.08 / MOSI P1.09) at 8 MHz over EasyDMA. Async
  ExclusiveDevice from embedded-hal-bus (with the 'async' feature).
- lcd-async builder at display_size(135, 240), display_offset(52, 40),
  Deg90 rotation, ColorInversion::Inverted — standard 1.14" ST7789
  die mapping.
- Linker: shared ld/nrf52840-memory.x (S140 SoftDevice preserved at
  0x01000-0x26000 per project policy).

Cargo.lock

@@ -608,6 +608,7 @@ dependencies = [
  "embedded-graphics",
  "embedded-hal 1.0.0",
  "embedded-hal-async",
+ "embedded-hal-bus",
  "embedded-io-async 0.7.0",
  "esp-backtrace",
  "esp-bootloader-esp-idf",
@@ -616,6 +617,7 @@ dependencies = [
  "esp-rtos",
  "heapless 0.9.2",
  "hsmc",
+ "lcd-async",
  "lora-phy",
  "minijinja",
  "owo-colors",
@@ -986,6 +988,17 @@ dependencies = [
  "embedded-hal 1.0.0",
 ]
 
+[[package]]
+name = "embedded-hal-bus"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "513e0b3a8fb7d3013a8ae17a834283f170deaf7d0eeab0a7c1a36ad4dd356d22"
+dependencies = [
+ "critical-section",
+ "embedded-hal 1.0.0",
+ "embedded-hal-async",
+]
+
 [[package]]
 name = "embedded-hal-nb"
 version = "1.0.0"
@@ -1744,6 +1757,18 @@ version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
+[[package]]
+name = "lcd-async"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "359805d2afdff45f3abad226ae27a61ee980309562d14084842c542af29b422a"
+dependencies = [
+ "embedded-graphics",
+ "embedded-graphics-core",
+ "embedded-hal 1.0.0",
+ "embedded-hal-async",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.186"

Cargo.toml

@@ -40,6 +40,21 @@ static_cell = "2.1"
 display-interface = "0.5"
 embedded-graphics = "0.8"
 ssd1306 = { version = "0.10", features = ["async"] }
+# T114 ST7789 TFT (color, async SPI). Optional — only pulled in by the
+# heltec_mesh_node_t114 feature. Mono OLED boards keep their existing
+# display-interface + ssd1306/sh1106 stack and don't pay for these.
+#
+# `lcd-async` is an async fork of mipidsi: same model/builder shape but
+# `init()` and pixel writes are `async fn`s. Combined with embassy-nrf's
+# DMA-backed async Spim, the dashboard repaint yields the executor for
+# the duration of the SPI transfer instead of busy-looping for ~65 ms,
+# so the radio task isn't starved.
+#
+# embedded-hal-bus needs the `async` feature for `ExclusiveDevice` to
+# implement `embedded_hal_async::spi::SpiDevice` (in addition to the
+# blocking impl).
+lcd-async = { version = "0.1", optional = true }
+embedded-hal-bus = { version = "0.3", optional = true, features = ["async"] }
 
 # Async IO traits and combinators
 embedded-io-async = "0.7"
@@ -252,6 +267,20 @@ wio_tracker_l1 = [
   "embassy-executor/platform-cortex-m",
   "embassy-executor/executor-thread",
 ]
+heltec_mesh_node_t114 = [
+  "embassy",
+  "trace-defmt",
+  "dep:cortex-m",
+  "dep:cortex-m-rt",
+  "cortex-m-rt/set-vtor",
+  "dep:defmt-rtt",
+  "dep:embassy-nrf",
+  "dep:panic-probe",
+  "dep:lcd-async",
+  "dep:embedded-hal-bus",
+  "embassy-executor/platform-cortex-m",
+  "embassy-executor/executor-thread",
+]
 waveshare_rp2040_lora = [
   "embassy",
   "trace-defmt",

README.md

@@ -20,6 +20,7 @@ All commands are run from the `firmware/` directory.
 
 | Board | Feature | MCU | Radio | USB | Target |
 |-------|---------|-----|-------|-----|--------|
+| Heltec Mesh Node T114 | `heltec_mesh_node_t114` | nRF52840 | SX1262 | Native CDC-ACM | thumbv7em-none-eabihf |
 | Heltec V3 | `heltec_v3` | ESP32-S3 | SX1262 | Native CDC-ACM | xtensa-esp32s3-none-elf |
 | Heltec V3 (UART) | `heltec_v3_uart` | ESP32-S3 | SX1262 | CP2102 bridge | xtensa-esp32s3-none-elf |
 | Heltec V4 | `heltec_v4` | ESP32-S3 | SX1262 | Native CDC-ACM | xtensa-esp32s3-none-elf |

justfile

@@ -13,7 +13,7 @@ version := `sed -n 's/^version = "\(.*\)"/\1/p' Cargo.toml`
 # Xtensa targets are built with `+esp` + `-Zbuild-std=core,alloc` (the
 # self-contained esp toolchain ships its own rust-src; the public
 # nightly drifts ahead and breaks core-stdlib compilation).
-boards := "heltec_v3 heltec_v3_uart heltec_v4 elecrow_thinknode_m2 lilygo_tbeam lilygo_tbeam_supreme rak_wisblock_4631 waveshare_rp2040_lora wio_tracker_l1"
+boards := "heltec_mesh_node_t114 heltec_v3 heltec_v3_uart heltec_v4 elecrow_thinknode_m2 lilygo_tbeam lilygo_tbeam_supreme rak_wisblock_4631 waveshare_rp2040_lora wio_tracker_l1"
 
 # Install all required tools and toolchains
 setup:
@@ -246,6 +246,7 @@ _flash_uf2 board:
 [private]
 _info name:
     @case "{{name}}" in \
+        heltec_mesh_node_t114) echo "heltec_mesh_node_t114 thumbv7em-none-eabihf nRF52840_xxAA" ;; \
         heltec_v3)             echo "heltec_v3 xtensa-esp32s3-none-elf esp32s3" ;; \
         heltec_v3_uart)        echo "heltec_v3_uart xtensa-esp32s3-none-elf esp32s3" ;; \
         heltec_v4)             echo "heltec_v4 xtensa-esp32s3-none-elf esp32s3" ;; \

src/board/PORTING.md

@@ -70,8 +70,10 @@ impl LoRaBoard for Board {
 ### 5. Add display init
 
 ```rust
-pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
-    // Construct and initialize your display driver (SSD1306, SH1106, etc.)
+pub async fn create_display(parts: DisplayParts) -> Option<DisplayDriver> {
+    // Construct and initialize your display driver (SSD1306, SH1106,
+    // ST7789, etc.) using whatever pins/buses you bundled into
+    // DisplayParts in `into_parts()`.
 }
 ```
 

src/board/elecrow_thinknode_m2.rs

@@ -48,8 +48,8 @@ pub struct DisplayParts {
 
 // ── Display init ────────────────────────────────────────────────────
 
-pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
-    let mut display = Sh1106::new(i2c, 0x3C);
+pub async fn create_display(parts: DisplayParts) -> Option<DisplayDriver> {
+    let mut display = Sh1106::new(parts.i2c, 0x3C);
 
     embassy_time::Timer::after_millis(100).await;
     if display.init().await.is_err() {

src/board/esp32.rs

@@ -47,13 +47,13 @@ pub type DisplayDriver = ssd1306::Ssd1306Async<
 >;
 
 /// Construct and initialize an SSD1306 display from raw I²C.
-pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
+pub async fn create_display(parts: DisplayParts) -> Option<DisplayDriver> {
     use ssd1306::mode::DisplayConfigAsync;
     use ssd1306::prelude::{Brightness, DisplayRotation};
     use ssd1306::size::DisplaySize128x64;
     use ssd1306::{I2CDisplayInterface, Ssd1306Async};
 
-    let interface = I2CDisplayInterface::new(i2c);
+    let interface = I2CDisplayInterface::new(parts.i2c);
     let mut display = Ssd1306Async::new(interface, DisplaySize128x64, DisplayRotation::Rotate0)
         .into_buffered_graphics_mode();
 

src/board/esp32s3.rs

@@ -63,13 +63,13 @@ pub type DisplayDriver = ssd1306::Ssd1306Async<
     feature = "heltec_v3_uart",
     feature = "heltec_v4"
 ))]
-pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
+pub async fn create_display(parts: DisplayParts) -> Option<DisplayDriver> {
     use ssd1306::mode::DisplayConfigAsync;
     use ssd1306::prelude::{Brightness, DisplayRotation};
     use ssd1306::size::DisplaySize128x64;
     use ssd1306::{I2CDisplayInterface, Ssd1306Async};
 
-    let interface = I2CDisplayInterface::new(i2c);
+    let interface = I2CDisplayInterface::new(parts.i2c);
     let mut display = Ssd1306Async::new(interface, DisplaySize128x64, DisplayRotation::Rotate0)
         .into_buffered_graphics_mode();
 

src/board/heltec_mesh_node_t114.rs

@@ -0,0 +1,285 @@
+//! Heltec Mesh Node T114 (nRF52840 + SX1262 + 1.14" ST7789 TFT).
+//!
+//! Hardware reference: cross-verified across MeshCore, Meshtastic, and
+//! RNode firmwares. Pin maps quoted from
+//! `meshcore-spec/references/MeshCore/variants/heltec_t114/variant.h` and
+//! `meshtastic/firmware/variants/nrf52840/heltec_mesh_node_t114/variant.h`.
+//!
+//! Stage 2: panel comes up with static colors via the `St7789Color`
+//! driver. Stage 3 swaps in the proper color renderer module.
+
+use embassy_embedded_hal::shared_bus::asynch::spi::SpiDevice;
+use embassy_nrf::gpio::{Input, Level, Output, OutputDrive, Pull};
+use embassy_nrf::pwm::{Prescaler, SimpleConfig, SimplePwm};
+use embassy_nrf::spim::{self, Spim};
+use embassy_nrf::usb::Driver;
+use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+use embassy_time::{Delay, Timer};
+
+use embedded_hal_bus::spi::ExclusiveDevice;
+use lcd_async::interface::SpiInterface;
+use lcd_async::models::ST7789;
+use lcd_async::options::{ColorInversion, Orientation, Rotation};
+use lora_phy::iv::GenericSx126xInterfaceVariant;
+use lora_phy::sx126x::{self, Sx1262, Sx126x};
+use static_cell::ConstStaticCell;
+
+use super::traits::{BoardParts, LoRaBoard};
+use crate::driver::inverted_pin::InvertedPin;
+use crate::driver::simple_led::SimpleLed;
+use crate::driver::st7789::{St7789Color, FB_BYTES};
+use crate::hal::nrf52840 as mcu;
+
+// ── Concrete peripheral types ───────────────────────────────────────
+
+type Nss = Output<'static>;
+type Iv = GenericSx126xInterfaceVariant<Output<'static>, Input<'static>>;
+type RadioSpiDevice = SpiDevice<'static, NoopRawMutex, mcu::SpiBus, Nss>;
+pub type RadioDriver = Sx126x<RadioSpiDevice, Iv, Sx1262>;
+pub type UsbDriver = mcu::UsbNrfDriver;
+// Green LED on P1.03, active LOW.
+pub type LedDriver = SimpleLed<InvertedPin<Output<'static>>>;
+
+// ── TFT bus and driver type aliases ─────────────────────────────────
+
+type TftSpim = Spim<'static>;
+type TftSpiDevice = ExclusiveDevice<TftSpim, Output<'static>, Delay>;
+type TftInterface = SpiInterface<TftSpiDevice, Output<'static>>;
+pub type DisplayDriver = St7789Color<TftInterface, Output<'static>>;
+
+// ── Peripheral bundles ──────────────────────────────────────────────
+
+pub struct RadioParts {
+    pub driver: RadioDriver,
+    pub delay: Delay,
+}
+
+pub struct UsbParts {
+    pub driver: UsbDriver,
+}
+
+/// Assembled-but-not-yet-initialized TFT plumbing. Real initialization
+/// (power gate, RST cycle, mipidsi init) happens in `create_display`.
+pub struct DisplayParts {
+    interface: TftInterface,
+    rst_pin: Output<'static>,
+    vdd_en: Output<'static>,
+    backlight: SimplePwm<'static>,
+}
+
+// ── Display init ────────────────────────────────────────────────────
+
+pub async fn create_display(parts: DisplayParts) -> Option<DisplayDriver> {
+    let DisplayParts {
+        interface,
+        rst_pin,
+        mut vdd_en,
+        mut backlight,
+    } = parts;
+
+    // 1. Drive TFT VDD enable LOW (active LOW per Meshtastic) and let
+    //    the rail settle. Heltec's schematic has the panel power gated
+    //    by P0.03 — touching SPI before VDD is stable produces snow.
+    vdd_en.set_low();
+    Timer::after_millis(50).await;
+
+    // 2. Build the lcd-async display.
+    //    The T114 panel is wired natively portrait (135w × 240h) at
+    //    chip framebuffer offset (52, 40) — the standard 1.14" 135×240
+    //    ST7789 die mapping. Deg90 rotation rotates the user-facing
+    //    surface to landscape (240w × 135h). Meshtastic's variant.h
+    //    sets TFT_OFFSET_X=0/Y=0 because their fork of TFT_eSPI applies
+    //    these offsets internally; lcd-async expects them in display_offset.
+    //    If the image comes up mirrored or upside-down, swap
+    //    Deg90 ↔ Deg270 or set `mirrored = true`.
+    let mut delay = Delay;
+    let panel = match lcd_async::Builder::new(ST7789, interface)
+        .reset_pin(rst_pin)
+        .display_size(135, 240)
+        .display_offset(52, 40)
+        .orientation(Orientation::new().rotate(Rotation::Deg90))
+        .invert_colors(ColorInversion::Inverted)
+        .init(&mut delay)
+        .await
+    {
+        Ok(p) => p,
+        Err(_) => {
+            defmt::error!("ST7789 init failed");
+            return None;
+        }
+    };
+    defmt::info!("ST7789 init OK");
+
+    // 3. Bring the backlight up at full brightness. Stage 2 uses the
+    //    full-on duty; the splash dimming logic handled by the display
+    //    statechart will hand off to set_dim/set_bright shortly.
+    backlight.set_duty(0, embassy_nrf::pwm::DutyCycle::inverted(0));
+
+    // Forget vdd_en so it stays driven for the lifetime of the program.
+    // We took it by move so we could call set_low() during init.
+    core::mem::forget(vdd_en);
+
+    // Take the static framebuffer (240×135 × 2 bytes Rgb565 BE
+    // = 64,800 bytes zero-initialized in .bss). Stored as raw bytes
+    // so present() can DMA-blit the slice straight to the panel
+    // without an iterator-conversion pass — the lcd-async
+    // `RawFrameBuf<Rgb565, _>` wrapper handles BE byte packing on
+    // each pixel write.
+    static FRAMEBUFFER: ConstStaticCell<[u8; FB_BYTES]> =
+        ConstStaticCell::new([0u8; FB_BYTES]);
+    let fb = FRAMEBUFFER.take();
+
+    Some(St7789Color::new(panel, backlight, fb))
+}
+
+// ── Board init ──────────────────────────────────────────────────────
+
+pub struct Board {
+    p: embassy_nrf::Peripherals,
+}
+
+impl LoRaBoard for Board {
+    const NAME: &'static str = "Heltec Mesh Node T114";
+    const TX_POWER_RANGE: (i8, i8) = (-9, 22);
+
+    type RadioParts = RadioParts;
+    type CommParts = UsbParts;
+    type DisplayParts = DisplayParts;
+    type DisplayDriver = DisplayDriver;
+    type LedDriver = LedDriver;
+
+    fn init() -> Self {
+        // USB requires the 32 MHz HFXO (±50 ppm); the RC oscillator is out of spec.
+        let mut config = embassy_nrf::config::Config::default();
+        config.hfclk_source = embassy_nrf::config::HfclkSource::ExternalXtal;
+        config.lfclk_source = embassy_nrf::config::LfclkSource::ExternalXtal;
+        let p = embassy_nrf::init(config);
+        Self { p }
+    }
+
+    fn mac_address() -> [u8; 6] {
+        mcu::mac_address()
+    }
+
+    fn into_parts(self) -> BoardParts<RadioParts, UsbParts, DisplayParts, LedDriver> {
+        let p = self.p;
+
+        // ── VEXT_ENABLE (P0.21, active HIGH) ────────────────────
+        // Powers the SX1262 *and* the TFT/peripheral 3V3 rail. Must be
+        // driven HIGH before any SPI traffic to the radio or panel —
+        // without this, lora-phy init can succeed (SPI bus works
+        // electrically) but TX_DONE never fires because the PA is
+        // unpowered. Held forever via core::mem::forget. Mirrors
+        // Meshtastic's `VEXT_ENABLE = P0.21, VEXT_ON_VALUE = HIGH`.
+        let vext_en = Output::new(p.P0_21, Level::High, OutputDrive::Standard);
+        core::mem::forget(vext_en);
+
+        // ── SPI3 bus for SX1262 ─────────────────────────────────
+        // Per Heltec T114 schematic + Meshtastic variant.h:
+        //   SCK=P0.19, MOSI=P0.22, MISO=P0.23
+        //   NSS=P0.24, RST=P0.25, BUSY=P0.17, DIO1=P0.20
+        // No external RXEN/TXEN — antenna switch is driven internally
+        // by SX1262 DIO2. TCXO is on DIO3 at 1.8 V.
+        let mut spi_cfg = spim::Config::default();
+        spi_cfg.frequency = spim::Frequency::M1;
+        let spi = Spim::new(p.SPI3, mcu::Irqs, p.P0_19, p.P0_23, p.P0_22, spi_cfg);
+        let spi_bus = mcu::share_spi_bus(spi);
+
+        let nss = Output::new(p.P0_24, Level::High, OutputDrive::Standard);
+        let spi_device = SpiDevice::new(spi_bus, nss);
+
+        let reset = Output::new(p.P0_25, Level::High, OutputDrive::Standard);
+        let dio1 = Input::new(p.P0_20, Pull::Down);
+        // BUSY has an internal 20 kΩ pull-up on the SX1262 die (datasheet
+        // p. 53); an MCU-side Pull fights it. See lora-rs/lora-rs#260.
+        let busy = Input::new(p.P0_17, Pull::None);
+
+        let iv = GenericSx126xInterfaceVariant::new(reset, dio1, busy, None, None)
+            .expect("SX1262 interface init");
+
+        let sx_config = sx126x::Config {
+            chip: Sx1262,
+            tcxo_ctrl: Some(sx126x::TcxoCtrlVoltage::Ctrl1V8),
+            use_dcdc: true,
+            rx_boost: false,
+        };
+
+        let radio = RadioParts {
+            driver: Sx126x::new(spi_device, iv, sx_config),
+            delay: Delay,
+        };
+
+        // ── USB ─────────────────────────────────────────────────
+        let vbus = mcu::alloc_vbus_detect(true, true);
+        let host = UsbParts {
+            driver: Driver::new(p.USBD, mcu::Irqs, vbus),
+        };
+
+        // Battery divider control (P0.06) LOW disables the divider —
+        // saves a few tens of µA. Battery sense (P0.04 / AIN2) deferred
+        // until the protocol gets a battery field.
+        let bat_ctl = Output::new(p.P0_06, Level::Low, OutputDrive::Standard);
+        core::mem::forget(bat_ctl);
+
+        // ── SPI2 bus for ST7789 TFT ─────────────────────────────
+        // Per Meshtastic variant.h:
+        //   SCK=P1.08, MOSI=P1.09, CS=P0.11, DC=P0.12, RST=P0.02
+        //   VDD enable=P0.03 (active HIGH), Backlight=P0.15 (active LOW PWM)
+        // Write-only bus — embassy_nrf::Spim still requires a MISO slot,
+        // so we wire a free unused pin (P1.06) as a no-op input.
+        let mut tft_spi_cfg = spim::Config::default();
+        // 8 MHz lets us repaint the 240×135 panel comfortably. Higher
+        // rates work with mipidsi but are platform-dependent (board
+        // routing, pull strengths). 8 MHz is the safe default.
+        tft_spi_cfg.frequency = spim::Frequency::M8;
+        let tft_spi = Spim::new(p.SPI2, mcu::Irqs, p.P1_08, p.P1_06, p.P1_09, tft_spi_cfg);
+
+        let tft_cs = Output::new(p.P0_11, Level::High, OutputDrive::Standard);
+        let tft_dc = Output::new(p.P0_12, Level::Low, OutputDrive::Standard);
+        let tft_rst = Output::new(p.P0_02, Level::High, OutputDrive::Standard);
+        // VTFT_CTRL is active LOW per Meshtastic
+        // (`#define TFT_BACKLIGHT_ON LOW`, `digitalWrite(VTFT_CTRL, LOW)`
+        // at boot). Start HIGH (panel rail off); create_display drives
+        // LOW to enable the panel.
+        let tft_vdd = Output::new(p.P0_03, Level::High, OutputDrive::Standard);
+
+        let tft_spi_device = ExclusiveDevice::new(tft_spi, tft_cs, Delay)
+            .expect("TFT ExclusiveDevice init");
+
+        // lcd-async's SpiInterface streams pixel data directly from
+        // the caller's slice — no scratch buffer required (mipidsi's
+        // sync version needed one for batching).
+        let tft_interface = SpiInterface::new(tft_spi_device, tft_dc);
+
+        // ── PWM backlight (active-LOW on P0.15) ─────────────────
+        // Default SimpleConfig is fine — countertop=1000 → ~1 kHz
+        // (well above flicker threshold), prescaler default. Channel 0
+        // idle level matches the active-LOW wiring.
+        let mut bl_cfg = SimpleConfig::default();
+        bl_cfg.max_duty = crate::driver::st7789::BL_MAX;
+        bl_cfg.prescaler = Prescaler::Div128;
+        bl_cfg.ch0_idle_level = Level::High;
+        let backlight = SimplePwm::new_1ch(p.PWM0, p.P0_15, &bl_cfg);
+
+        let display_parts = DisplayParts {
+            interface: tft_interface,
+            rst_pin: tft_rst,
+            vdd_en: tft_vdd,
+            backlight,
+        };
+
+        // ── Green LED (P1.03, active LOW) ───────────────────────
+        // Idle level HIGH = LED off. InvertedPin flips polarity so
+        // SimpleLed can use normal "set_high = on" semantics.
+        let led_pin = Output::new(p.P1_03, Level::High, OutputDrive::Standard);
+        let led = SimpleLed(InvertedPin(led_pin));
+
+        BoardParts {
+            radio,
+            host,
+            display: Some(display_parts),
+            led,
+            mac: Self::mac_address(),
+        }
+    }
+}

src/board/lilygo_tbeam_supreme.rs

@@ -50,8 +50,8 @@ pub struct DisplayParts {
 
 // ── Display init ────────────────────────────────────────────────────
 
-pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
-    let mut display = Sh1106::new(i2c, 0x3C);
+pub async fn create_display(parts: DisplayParts) -> Option<DisplayDriver> {
+    let mut display = Sh1106::new(parts.i2c, 0x3C);
 
     embassy_time::Timer::after_millis(100).await;
     if display.init().await.is_err() {

src/board/rak_wisblock_4631.rs

@@ -52,8 +52,8 @@ pub struct DisplayParts {
 
 // ── Display init ────────────────────────────────────────────────────
 
-pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
-    let mut display = crate::driver::sh1106::Sh1106::new(i2c, 0x3C);
+pub async fn create_display(parts: DisplayParts) -> Option<DisplayDriver> {
+    let mut display = crate::driver::sh1106::Sh1106::new(parts.i2c, 0x3C);
 
     // Retry 3× with 100ms backoff. The SH1106's first transaction
     // after power-on can return Err if the chip's internal voltage

src/board/traits.rs

@@ -6,10 +6,7 @@
 //!
 //! 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;
-
-use crate::driver::DisplayBrightness;
+use crate::display::BoardDisplay;
 
 /// Async RGB LED control. Boards without an LED use `()` which is a no-op.
 pub trait RgbLed {
@@ -37,9 +34,10 @@ pub trait LoRaBoard: Sized {
     /// Display peripheral bundle (I2C bus for display init).
     type DisplayParts;
 
-    /// Concrete display driver type (must implement DrawTarget for rendering
-    /// and DisplayBrightness for the two-level dim control).
-    type DisplayDriver: DrawTarget<Color = BinaryColor> + DisplayBrightness;
+    /// Concrete display driver type. Each board's driver implements
+    /// [`BoardDisplay`] to render the splash + dashboard content into its
+    /// native pixel format and resolution and to flush / dim the panel.
+    type DisplayDriver: BoardDisplay;
 
     /// RGB LED driver. Boards without an LED use `()`.
     type LedDriver: RgbLed;

src/board/waveshare_rp2040_lora.rs

@@ -41,12 +41,16 @@ pub struct UsbParts {
 }
 
 pub struct DisplayParts {
+    // No display on this board, but the trait still wants concrete
+    // peripheral types. The i2c bus type is reserved for the future
+    // possibility of an external OLED add-on.
+    #[allow(dead_code)]
     pub i2c: DisplayI2c,
 }
 
 // ── Display init ───────────────────────────────────────────────────
 
-pub async fn create_display(_i2c: DisplayI2c) -> Option<DisplayDriver> {
+pub async fn create_display(_parts: DisplayParts) -> Option<DisplayDriver> {
     None
 }
 

src/board/wio_tracker_l1.rs

@@ -42,8 +42,8 @@ pub struct DisplayParts {
 
 // ── Display init ────────────────────────────────────────────────────
 
-pub async fn create_display(i2c: DisplayI2c) -> Option<DisplayDriver> {
-    let mut display = crate::driver::sh1106::Sh1106::new(i2c, 0x3D);
+pub async fn create_display(parts: DisplayParts) -> Option<DisplayDriver> {
+    let mut display = crate::driver::sh1106::Sh1106::new(parts.i2c, 0x3D);
 
     embassy_time::Timer::after_millis(100).await;
     if display.init().await.is_err() {

src/display.rs

@@ -38,27 +38,29 @@ use hsmc::statechart;
 
 use crate::board::{self, Board, DisplayDriver, DisplayParts, LedDriver, LoRaBoard, RgbLed};
 use crate::channel::{DisplayCommand, DisplayCommandChannel, RadioEvent, RadioEventChannel};
-use crate::driver::DisplayBrightness;
 use crate::protocol::LoRaConfig;
 
-use render::{BoardInfo, RSSI_HISTORY_LEN};
-
 const BOARD_NAME: &str = Board::NAME;
 const VERSION: &str = env!("CARGO_PKG_VERSION");
 
-// Splash board-name font selection. Every OLED we drive is 128 px wide;
-// the primary font (FONT_6X10, 6 px advance) fits up to 21 ASCII chars
-// across the screen, the fallback (FONT_5X8, 5 px advance) fits up to
-// 25. If even the fallback can't fit, fail at compile time so the board
-// porter shortens NAME rather than silently overflowing the splash.
+/// Number of slots in the dashboard's RSSI/TX sparkline ring buffer.
+pub const RSSI_HISTORY_LEN: usize = 128;
+
+// Mono splash board-name font selection. The mono OLEDs we drive are
+// 128 px wide; the primary font (FONT_6X10, 6 px advance) fits up to 21
+// ASCII chars across, the fallback (FONT_5X8, 5 px advance) fits up to
+// 25. If even the fallback can't fit on a mono OLED, fail at compile
+// time so the board porter shortens NAME rather than silently
+// overflowing the splash. Color renderers have their own size budget
+// and simply use the same NAME with their own font choice.
 const SPLASH_SCREEN_W_PX: u32 = 128;
 const SPLASH_FONT_PRIMARY_W_PX: u32 = 6;
 const SPLASH_FONT_FALLBACK_W_PX: u32 = 5;
-const BOARD_NAME_FITS_PRIMARY_FONT: bool =
+pub(crate) const BOARD_NAME_FITS_PRIMARY_FONT: bool =
     (BOARD_NAME.len() as u32) * SPLASH_FONT_PRIMARY_W_PX <= SPLASH_SCREEN_W_PX;
 const _: () = assert!(
     (BOARD_NAME.len() as u32) * SPLASH_FONT_FALLBACK_W_PX <= SPLASH_SCREEN_W_PX,
-    "Board::NAME is too long for the 128 px splash screen even with the FONT_5X8 fallback \
+    "Board::NAME is too long for the 128 px mono splash screen even with the FONT_5X8 fallback \
      (max 25 ASCII chars). Shorten the NAME constant in src/board/<board>.rs.",
 );
 
@@ -66,6 +68,49 @@ const _: () = assert!(
 /// floor (-120 dBm), so it cannot be confused with a real RSSI value.
 const NO_SIGNAL: i16 = -121;
 
+/// Hand-authored 64 × 64 pixel-perfect QR bitmap for the splash
+/// "learn more" screen. 1 bit/pixel, MSB-first, row-major. Bit `1` is
+/// "light" (OLED pixel on), bit `0` is "dark" (OLED pixel off), so when
+/// drawn with `BinaryColor::On` = lit, the QR appears with the
+/// traditional dark-on-light look including a proper quiet zone. The
+/// color renderer remaps bit 1 → white, bit 0 → black for the same
+/// visual contrast on a black-background TFT.
+pub(crate) const QR_WIDTH_PX: u32 = 64;
+pub(crate) const QR_BITMAP: [u8; 512] = [
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0x00, 0x07, 0x9F, 0xFE, 0x60, 0x00, 0x7F, 0xFE,
+    0x00, 0x07, 0x9F, 0xFE, 0x60, 0x00, 0x7F, 0xFE, 0x7F, 0xE6, 0x18, 0x19, 0xE7, 0xFE, 0x7F, 0xFE,
+    0x7F, 0xE6, 0x18, 0x19, 0xE7, 0xFE, 0x7F, 0xFE, 0x60, 0x67, 0x81, 0xE6, 0x66, 0x06, 0x7F, 0xFE,
+    0x60, 0x67, 0x81, 0xE6, 0x66, 0x06, 0x7F, 0xFE, 0x60, 0x66, 0x19, 0x87, 0xE6, 0x06, 0x7F, 0xFE,
+    0x60, 0x66, 0x19, 0x87, 0xE6, 0x06, 0x7F, 0xFE, 0x60, 0x67, 0xE6, 0x1F, 0xE6, 0x06, 0x7F, 0xFE,
+    0x60, 0x67, 0xE6, 0x1F, 0xE6, 0x06, 0x7F, 0xFE, 0x7F, 0xE6, 0x67, 0x80, 0x67, 0xFE, 0x7F, 0xFE,
+    0x7F, 0xE6, 0x67, 0x80, 0x67, 0xFE, 0x7F, 0xFE, 0x00, 0x06, 0x66, 0x66, 0x60, 0x00, 0x7F, 0xFE,
+    0x00, 0x06, 0x66, 0x66, 0x60, 0x00, 0x7F, 0xFF, 0xFF, 0xFF, 0xFE, 0x61, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFE, 0x61, 0xFF, 0xFF, 0xFF, 0xFE, 0x00, 0x60, 0x06, 0x01, 0x99, 0x99, 0xFF, 0xFE,
+    0x00, 0x60, 0x06, 0x01, 0x99, 0x99, 0xFF, 0xFE, 0x01, 0x98, 0x1F, 0x9E, 0x79, 0xF9, 0xFF, 0xFE,
+    0x01, 0x98, 0x1F, 0x9E, 0x79, 0xF9, 0xFF, 0xFF, 0xE0, 0x66, 0x18, 0x61, 0x9F, 0x98, 0x7F, 0xFF,
+    0xE0, 0x66, 0x18, 0x61, 0x9F, 0x98, 0x7F, 0xFF, 0x98, 0x1E, 0x01, 0xE7, 0x99, 0xFE, 0x7F, 0xFF,
+    0x98, 0x1E, 0x01, 0xE7, 0x99, 0xFE, 0x7F, 0xFF, 0xE1, 0xE6, 0x19, 0xF8, 0x06, 0x60, 0x7F, 0xFF,
+    0xE1, 0xE6, 0x19, 0xF8, 0x06, 0x60, 0x7F, 0xFE, 0x19, 0xF8, 0x06, 0x1E, 0x79, 0x99, 0xFF, 0xFE,
+    0x19, 0xF8, 0x06, 0x1E, 0x79, 0x99, 0xFF, 0xFE, 0x7E, 0x01, 0xFF, 0x80, 0x18, 0x18, 0x7F, 0xFE,
+    0x7E, 0x01, 0xFF, 0x80, 0x18, 0x18, 0x7F, 0xFE, 0x7E, 0x19, 0x9E, 0x1E, 0x78, 0x7E, 0x7F, 0xFE,
+    0x7E, 0x19, 0x9E, 0x1E, 0x78, 0x7E, 0x7F, 0xFE, 0x60, 0x06, 0x66, 0x66, 0x00, 0x67, 0xFF, 0xFE,
+    0x60, 0x06, 0x66, 0x66, 0x00, 0x67, 0xFF, 0xFF, 0xFF, 0xFE, 0x67, 0xF8, 0x7E, 0x1F, 0xFF, 0xFF,
+    0xFF, 0xFE, 0x67, 0xF8, 0x7E, 0x1F, 0xFF, 0xFE, 0x00, 0x06, 0x00, 0x7E, 0x66, 0x60, 0x7F, 0xFE,
+    0x00, 0x06, 0x00, 0x7E, 0x66, 0x60, 0x7F, 0xFE, 0x7F, 0xE7, 0x99, 0xE6, 0x7E, 0x1E, 0x7F, 0xFE,
+    0x7F, 0xE7, 0x99, 0xE6, 0x7E, 0x1E, 0x7F, 0xFE, 0x60, 0x66, 0x61, 0xF8, 0x00, 0x60, 0x7F, 0xFE,
+    0x60, 0x66, 0x61, 0xF8, 0x00, 0x60, 0x7F, 0xFE, 0x60, 0x66, 0x06, 0x01, 0x86, 0x00, 0x7F, 0xFE,
+    0x60, 0x66, 0x06, 0x01, 0x86, 0x00, 0x7F, 0xFE, 0x60, 0x66, 0x67, 0x86, 0x7F, 0x86, 0x7F, 0xFE,
+    0x60, 0x66, 0x67, 0x86, 0x7F, 0x86, 0x7F, 0xFE, 0x7F, 0xE6, 0x66, 0x18, 0x00, 0x1E, 0x7F, 0xFE,
+    0x7F, 0xE6, 0x66, 0x18, 0x00, 0x1E, 0x7F, 0xFE, 0x00, 0x06, 0x66, 0x67, 0x98, 0x00, 0x7F, 0xFE,
+    0x00, 0x06, 0x66, 0x67, 0x98, 0x00, 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+    0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+];
+
 /// Which dashboard badge is in view (drives the RX/TX indicator only).
 #[derive(Debug, Clone, Copy)]
 pub enum Badge {
@@ -73,6 +118,136 @@ pub enum Badge {
     Tx,
 }
 
+// ── Display content types (shared across all renderers) ───────────────
+//
+// `BoardInfo` and `DashboardCtx` describe *what* to draw on the splash
+// and dashboard screens. Each board's `BoardDisplay` impl decides *how*
+// to render that content for its native pixel format and resolution.
+
+/// Static-ish board identity rendered on the splash + dashboard.
+pub struct BoardInfo<'a> {
+    pub name: &'a str,
+    pub version: &'a str,
+    pub mac: &'a str,
+}
+
+/// Live dashboard data at the moment of a render call.
+pub struct DashboardCtx<'a> {
+    pub badge: Badge,
+    pub config: Option<LoRaConfig>,
+    pub rx_count: u32,
+    pub tx_count: u32,
+    pub last_rssi: Option<i16>,
+    pub last_snr: Option<i16>,
+    pub rssi_history: &'a [i16; RSSI_HISTORY_LEN],
+    pub tx_history: &'a [bool; RSSI_HISTORY_LEN],
+    pub rssi_count: usize,
+    pub current_slot_rssi: i16,
+    pub current_slot_tx: bool,
+    pub board: &'a BoardInfo<'a>,
+}
+
+// ── BoardDisplay trait ────────────────────────────────────────────────
+//
+// One logical display surface, four content states (splash×2, dashboard,
+// blank), plus brightness control and a flush hook. Each board's display
+// driver implements this directly — color depth, resolution, dimming
+// strategy, and any framebuffer flushing live behind the trait.
+
+/// Single trait every board's display driver implements. The display
+/// task talks to the trait; the per-driver impl handles native format.
+///
+/// `present()` is named distinctly from any inherent `flush()` method on
+/// concrete display types so method resolution doesn't get ambiguous.
+pub trait BoardDisplay {
+    fn present(&mut self) -> impl core::future::Future<Output = ()>;
+    fn set_bright(&mut self) -> impl core::future::Future<Output = ()>;
+    fn set_dim(&mut self) -> impl core::future::Future<Output = ()>;
+
+    fn render_splash_learn_more(&mut self);
+    fn render_splash_info(&mut self, info: &BoardInfo<'_>);
+    fn render_dashboard(&mut self, ctx: &DashboardCtx<'_>);
+    fn render_blank(&mut self);
+}
+
+// Color renderer module — used by `crate::driver::st7789::St7789Color` on
+// the Heltec T114 to draw native 240×135 Rgb565 dashboards/splash screens.
+// Gated to the T114 feature so other boards don't pay for the imports.
+#[cfg(feature = "heltec_mesh_node_t114")]
+pub mod render_color;
+
+// Shared QR-code blit, generic over color. Used by both the mono and
+// color splash screens to render the bitmap with proper quiet zones.
+mod qr;
+
+// ── Mono-OLED adapters ────────────────────────────────────────────────
+//
+// SH1106 + SSD1306Async both render `BinaryColor` content into a 128×64
+// framebuffer flushed via I2C. Their `BoardDisplay` impls all delegate
+// to `mod render` — the existing pixel-perfect mono renderer.
+
+#[cfg(any(
+    feature = "wio_tracker_l1",
+    feature = "elecrow_thinknode_m2",
+    feature = "lilygo_tbeam_supreme",
+    feature = "rak_wisblock_4631"
+))]
+impl<I> BoardDisplay for crate::driver::sh1106::Sh1106<I>
+where
+    I: embedded_hal_async::i2c::I2c,
+{
+    async fn present(&mut self) {
+        let _ = crate::driver::sh1106::Sh1106::flush(self).await;
+    }
+    async fn set_bright(&mut self) {
+        crate::driver::DisplayBrightness::set_bright(self).await;
+    }
+    async fn set_dim(&mut self) {
+        crate::driver::DisplayBrightness::set_dim(self).await;
+    }
+    fn render_splash_learn_more(&mut self) {
+        render::learn_more(self);
+    }
+    fn render_splash_info(&mut self, info: &BoardInfo<'_>) {
+        render::info(self, info);
+    }
+    fn render_dashboard(&mut self, ctx: &DashboardCtx<'_>) {
+        render::dashboard(self, ctx);
+    }
+    fn render_blank(&mut self) {
+        render::blank(self);
+    }
+}
+
+impl<DI, SIZE> BoardDisplay
+    for ssd1306::Ssd1306Async<DI, SIZE, ssd1306::mode::BufferedGraphicsModeAsync<SIZE>>
+where
+    DI: display_interface::AsyncWriteOnlyDataCommand,
+    SIZE: ssd1306::size::DisplaySizeAsync,
+{
+    async fn present(&mut self) {
+        let _ = ssd1306::Ssd1306Async::flush(self).await;
+    }
+    async fn set_bright(&mut self) {
+        crate::driver::DisplayBrightness::set_bright(self).await;
+    }
+    async fn set_dim(&mut self) {
+        crate::driver::DisplayBrightness::set_dim(self).await;
+    }
+    fn render_splash_learn_more(&mut self) {
+        render::learn_more(self);
+    }
+    fn render_splash_info(&mut self, info: &BoardInfo<'_>) {
+        render::info(self, info);
+    }
+    fn render_dashboard(&mut self, ctx: &DashboardCtx<'_>) {
+        render::dashboard(self, ctx);
+    }
+    fn render_blank(&mut self) {
+        render::blank(self);
+    }
+}
+
 /// Fine-grained events driving the `Display` statechart.
 #[derive(Debug, Clone)]
 pub enum DisplayEvent {
@@ -180,14 +355,14 @@ impl DisplayContext {
             version: VERSION,
             mac: mac_str,
         };
-        render::info(display, &info);
-        let _ = display.flush().await;
+        display.render_splash_info(&info);
+        display.present().await;
     }
 
     async fn flush_learn_more(&mut self) {
         let display = &mut self.peripherals.display;
-        render::learn_more(display);
-        let _ = display.flush().await;
+        display.render_splash_learn_more();
+        display.present().await;
     }
 
     async fn flush_dashboard(&mut self, badge: Badge) {
@@ -199,27 +374,28 @@ impl DisplayContext {
             version: VERSION,
             mac: mac_str,
         };
-        render::dashboard(
-            display,
+        let ctx = DashboardCtx {
             badge,
-            self.run.config,
-            self.run.rx_count,
-            self.run.tx_count,
-            self.run.last_rssi,
-            self.run.last_snr,
-            &self.run.rssi_history,
-            &self.run.tx_history,
-            self.run.rssi_count,
-            self.run.current_slot_rssi,
-            self.run.current_slot_tx,
-            &info,
-        );
-        let _ = display.flush().await;
+            config: self.run.config,
+            rx_count: self.run.rx_count,
+            tx_count: self.run.tx_count,
+            last_rssi: self.run.last_rssi,
+            last_snr: self.run.last_snr,
+            rssi_history: &self.run.rssi_history,
+            tx_history: &self.run.tx_history,
+            rssi_count: self.run.rssi_count,
+            current_slot_rssi: self.run.current_slot_rssi,
+            current_slot_tx: self.run.current_slot_tx,
+            board: &info,
+        };
+        display.render_dashboard(&ctx);
+        display.present().await;
     }
 
     async fn flush_blank(&mut self) {
-        render::blank(&mut self.peripherals.display);
-        let _ = self.peripherals.display.flush().await;
+        let display = &mut self.peripherals.display;
+        display.render_blank();
+        display.present().await;
     }
 
     // Boards without an LED use `LedDriver = ()`; the `RgbLed for ()` impl
@@ -453,7 +629,7 @@ pub async fn display_task(
         ),
     );
 
-    let Some(display) = board::create_display(parts.i2c).await else {
+    let Some(display) = board::create_display(parts).await else {
         defmt::error!("display init failed, running LED-only loop");
         loop {
             match display_commands.receive().await {
@@ -516,10 +692,8 @@ mod render {
     use embedded_graphics::text::{Alignment, Text};
     use heapless::String;
 
-    use super::Badge;
-    use crate::protocol::{LoRaBandwidth, LoRaConfig};
-
-    pub const RSSI_HISTORY_LEN: usize = 128;
+    use super::{Badge, BoardInfo, DashboardCtx, QR_WIDTH_PX, RSSI_HISTORY_LEN};
+    use crate::protocol::LoRaBandwidth;
 
     const CHAR_W: i32 = 6;
     const FONT_H: i32 = 10;
@@ -528,72 +702,20 @@ mod render {
     const RSSI_MIN: i16 = -120;
     const RSSI_MAX: i16 = 0;
 
-    /// Hand-authored 64 × 64 pixel-perfect QR bitmap for the splash
-    /// "learn more" screen. 1 bit/pixel, MSB-first, row-major. Bit `1` is
-    /// "light" (OLED pixel on), bit `0` is "dark" (OLED pixel off), so
-    /// when drawn with `BinaryColor::On` = lit, the QR appears with the
-    /// traditional dark-on-light look including a proper quiet zone.
-    const QR_WIDTH_PX: u32 = 64;
-    const QR_BITMAP: [u8; 512] = [
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0x00, 0x07, 0x9F,
-        0xFE, 0x60, 0x00, 0x7F, 0xFE, 0x00, 0x07, 0x9F, 0xFE, 0x60, 0x00, 0x7F, 0xFE, 0x7F, 0xE6,
-        0x18, 0x19, 0xE7, 0xFE, 0x7F, 0xFE, 0x7F, 0xE6, 0x18, 0x19, 0xE7, 0xFE, 0x7F, 0xFE, 0x60,
-        0x67, 0x81, 0xE6, 0x66, 0x06, 0x7F, 0xFE, 0x60, 0x67, 0x81, 0xE6, 0x66, 0x06, 0x7F, 0xFE,
-        0x60, 0x66, 0x19, 0x87, 0xE6, 0x06, 0x7F, 0xFE, 0x60, 0x66, 0x19, 0x87, 0xE6, 0x06, 0x7F,
-        0xFE, 0x60, 0x67, 0xE6, 0x1F, 0xE6, 0x06, 0x7F, 0xFE, 0x60, 0x67, 0xE6, 0x1F, 0xE6, 0x06,
-        0x7F, 0xFE, 0x7F, 0xE6, 0x67, 0x80, 0x67, 0xFE, 0x7F, 0xFE, 0x7F, 0xE6, 0x67, 0x80, 0x67,
-        0xFE, 0x7F, 0xFE, 0x00, 0x06, 0x66, 0x66, 0x60, 0x00, 0x7F, 0xFE, 0x00, 0x06, 0x66, 0x66,
-        0x60, 0x00, 0x7F, 0xFF, 0xFF, 0xFF, 0xFE, 0x61, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE,
-        0x61, 0xFF, 0xFF, 0xFF, 0xFE, 0x00, 0x60, 0x06, 0x01, 0x99, 0x99, 0xFF, 0xFE, 0x00, 0x60,
-        0x06, 0x01, 0x99, 0x99, 0xFF, 0xFE, 0x01, 0x98, 0x1F, 0x9E, 0x79, 0xF9, 0xFF, 0xFE, 0x01,
-        0x98, 0x1F, 0x9E, 0x79, 0xF9, 0xFF, 0xFF, 0xE0, 0x66, 0x18, 0x61, 0x9F, 0x98, 0x7F, 0xFF,
-        0xE0, 0x66, 0x18, 0x61, 0x9F, 0x98, 0x7F, 0xFF, 0x98, 0x1E, 0x01, 0xE7, 0x99, 0xFE, 0x7F,
-        0xFF, 0x98, 0x1E, 0x01, 0xE7, 0x99, 0xFE, 0x7F, 0xFF, 0xE1, 0xE6, 0x19, 0xF8, 0x06, 0x60,
-        0x7F, 0xFF, 0xE1, 0xE6, 0x19, 0xF8, 0x06, 0x60, 0x7F, 0xFE, 0x19, 0xF8, 0x06, 0x1E, 0x79,
-        0x99, 0xFF, 0xFE, 0x19, 0xF8, 0x06, 0x1E, 0x79, 0x99, 0xFF, 0xFE, 0x7E, 0x01, 0xFF, 0x80,
-        0x18, 0x18, 0x7F, 0xFE, 0x7E, 0x01, 0xFF, 0x80, 0x18, 0x18, 0x7F, 0xFE, 0x7E, 0x19, 0x9E,
-        0x1E, 0x78, 0x7E, 0x7F, 0xFE, 0x7E, 0x19, 0x9E, 0x1E, 0x78, 0x7E, 0x7F, 0xFE, 0x60, 0x06,
-        0x66, 0x66, 0x00, 0x67, 0xFF, 0xFE, 0x60, 0x06, 0x66, 0x66, 0x00, 0x67, 0xFF, 0xFF, 0xFF,
-        0xFE, 0x67, 0xF8, 0x7E, 0x1F, 0xFF, 0xFF, 0xFF, 0xFE, 0x67, 0xF8, 0x7E, 0x1F, 0xFF, 0xFE,
-        0x00, 0x06, 0x00, 0x7E, 0x66, 0x60, 0x7F, 0xFE, 0x00, 0x06, 0x00, 0x7E, 0x66, 0x60, 0x7F,
-        0xFE, 0x7F, 0xE7, 0x99, 0xE6, 0x7E, 0x1E, 0x7F, 0xFE, 0x7F, 0xE7, 0x99, 0xE6, 0x7E, 0x1E,
-        0x7F, 0xFE, 0x60, 0x66, 0x61, 0xF8, 0x00, 0x60, 0x7F, 0xFE, 0x60, 0x66, 0x61, 0xF8, 0x00,
-        0x60, 0x7F, 0xFE, 0x60, 0x66, 0x06, 0x01, 0x86, 0x00, 0x7F, 0xFE, 0x60, 0x66, 0x06, 0x01,
-        0x86, 0x00, 0x7F, 0xFE, 0x60, 0x66, 0x67, 0x86, 0x7F, 0x86, 0x7F, 0xFE, 0x60, 0x66, 0x67,
-        0x86, 0x7F, 0x86, 0x7F, 0xFE, 0x7F, 0xE6, 0x66, 0x18, 0x00, 0x1E, 0x7F, 0xFE, 0x7F, 0xE6,
-        0x66, 0x18, 0x00, 0x1E, 0x7F, 0xFE, 0x00, 0x06, 0x66, 0x67, 0x98, 0x00, 0x7F, 0xFE, 0x00,
-        0x06, 0x66, 0x67, 0x98, 0x00, 0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
-        0xFF, 0xFF,
-    ];
 
-    pub struct BoardInfo<'a> {
-        pub name: &'a str,
-        pub version: &'a str,
-        pub mac: &'a str,
-    }
-
-    #[allow(clippy::too_many_arguments)]
-    pub fn dashboard(
-        target: &mut impl DrawTarget<Color = BinaryColor>,
-        badge: Badge,
-        config: Option<LoRaConfig>,
-        rx_count: u32,
-        tx_count: u32,
-        last_rssi: Option<i16>,
-        last_snr: Option<i16>,
-        rssi_history: &[i16; RSSI_HISTORY_LEN],
-        tx_history: &[bool; RSSI_HISTORY_LEN],
-        rssi_count: usize,
-        current_slot_rssi: i16,
-        current_slot_tx: bool,
-        board: &BoardInfo,
-    ) {
+    pub fn dashboard(target: &mut impl DrawTarget<Color = BinaryColor>, ctx: &DashboardCtx<'_>) {
+        let badge = ctx.badge;
+        let config = ctx.config;
+        let rx_count = ctx.rx_count;
+        let tx_count = ctx.tx_count;
+        let last_rssi = ctx.last_rssi;
+        let last_snr = ctx.last_snr;
+        let rssi_history = ctx.rssi_history;
+        let tx_history = ctx.tx_history;
+        let rssi_count = ctx.rssi_count;
+        let current_slot_rssi = ctx.current_slot_rssi;
+        let current_slot_tx = ctx.current_slot_tx;
+        let board = ctx.board;
         let bb = target.bounding_box();
         let w = bb.size.width as i32;
         let h = bb.size.height as i32;
@@ -833,10 +955,9 @@ mod render {
     }
 
     /// Alternate splash screen: 64 × 64 pixel-perfect QR bitmap on the
-    /// right (with its own quiet zone baked in), centered text column on
-    /// the left inviting the user to visit the URL.
+    /// right (centered within its quiet zone via `super::qr::draw`),
+    /// centered text column on the left inviting the user to visit the URL.
     pub fn learn_more(target: &mut impl DrawTarget<Color = BinaryColor>) {
-        use embedded_graphics::image::{Image, ImageRaw};
         use embedded_graphics::mono_font::ascii::{FONT_4X6, FONT_7X14_BOLD};
 
         let bb = target.bounding_box();
@@ -844,10 +965,14 @@ mod render {
 
         let _ = target.clear(BinaryColor::Off);
 
-        // ── QR code: flush to the right edge, 1:1 pixel rendering ───
+        // ── QR code: rightmost 64 × 64 region, centered cells ───────
         let qr_x = w - QR_WIDTH_PX as i32;
-        let qr_raw: ImageRaw<BinaryColor> = ImageRaw::new(&QR_BITMAP, QR_WIDTH_PX);
-        Image::new(&qr_raw, Point::new(qr_x, 0)).draw(target).ok();
+        super::qr::draw(
+            target,
+            Point::new(qr_x, 0),
+            BinaryColor::On,
+            BinaryColor::Off,
+        );
 
         // ── Text column (everything left of the QR) ─────────────────
         let col_w = qr_x;

src/display/qr.rs

@@ -0,0 +1,74 @@
+//! Shared QR-code blit for splash screens.
+//!
+//! The 512-byte QR bitmap in the parent module is laid out asymmetrically
+//! within its 64×64 frame: rows 0-6 and 57-63 are top/bottom quiet zones,
+//! but the QR cells start at col 0 (no left quiet zone) and extend to
+//! col ~49, leaving ~14 px of white padding on the right plus one stray
+//! black pixel at col 63. Rendering the bitmap as-is leaves the QR
+//! visually shifted toward the left of its rendering area, which looks
+//! wrong on any layout that doesn't tuck the bitmap flush against a
+//! screen edge.
+//!
+//! [`draw`] re-centers the QR data: it skips the bitmap's right padding
+//! (cols 50-63), fills the rendering area's left and right 7 px with
+//! the foreground "quiet zone" color, and renders the actual QR cells
+//! (bitmap cols 0..50) at +7 horizontal offset. Rows are rendered as-is
+//! so the bitmap's existing top/bottom quiet zones land where expected.
+//!
+//! Generic over color so the mono renderer (`BinaryColor`) and the
+//! T114's color renderer (`Rgb565`) share a single implementation —
+//! they pass their own foreground (white / lit) and background (black /
+//! unlit) values.
+
+use embedded_graphics::draw_target::DrawTarget;
+use embedded_graphics::geometry::{Point, Size};
+use embedded_graphics::pixelcolor::PixelColor;
+use embedded_graphics::primitives::Rectangle;
+use embedded_graphics::Pixel;
+
+use super::{QR_BITMAP, QR_WIDTH_PX};
+
+/// Width of the actual QR data within the bitmap (cols 0..QR_DATA_W).
+const QR_DATA_W: i32 = 50;
+/// White padding on left + right to center the QR cells. With
+/// QR_DATA_W=50 and total area=64 (= QR_WIDTH_PX), padding = 7 each side.
+const PAD_X: i32 = (QR_WIDTH_PX as i32 - QR_DATA_W) / 2;
+
+/// Render the 64×64 QR with proper quiet zones on all four sides.
+///
+/// `fg` is the "quiet zone / light cell" color (white on a TFT, "on"
+/// on a mono OLED). `bg` is the "dark cell" color. Bitmap rows 0-6 and
+/// 57-63 already encode top/bottom quiet zones in `fg`; this function
+/// fills the missing left/right padding columns explicitly.
+pub fn draw<D, C>(target: &mut D, origin: Point, fg: C, bg: C)
+where
+    D: DrawTarget<Color = C>,
+    C: PixelColor,
+{
+    // Fill left padding (cols 0..PAD_X) with fg.
+    let _ = target.fill_solid(
+        &Rectangle::new(origin, Size::new(PAD_X as u32, QR_WIDTH_PX)),
+        fg,
+    );
+    // Fill right padding (cols PAD_X+QR_DATA_W..QR_WIDTH_PX) with fg.
+    let right_pad_w = QR_WIDTH_PX as i32 - PAD_X - QR_DATA_W;
+    let _ = target.fill_solid(
+        &Rectangle::new(
+            Point::new(origin.x + PAD_X + QR_DATA_W, origin.y),
+            Size::new(right_pad_w as u32, QR_WIDTH_PX),
+        ),
+        fg,
+    );
+
+    // Render bitmap cols 0..QR_DATA_W at +PAD_X horizontal offset.
+    let bytes_per_row = (QR_WIDTH_PX / 8) as usize;
+    let pixels = (0..QR_WIDTH_PX as i32).flat_map(move |y| {
+        (0..QR_DATA_W).map(move |x| {
+            let byte = QR_BITMAP[y as usize * bytes_per_row + (x as usize) / 8];
+            let bit = (byte >> (7 - (x as u8 & 7))) & 1;
+            let color = if bit == 1 { fg } else { bg };
+            Pixel(Point::new(origin.x + PAD_X + x, origin.y + y), color)
+        })
+    });
+    let _ = target.draw_iter(pixels);
+}

src/display/render_color.rs

@@ -0,0 +1,422 @@
+//! Native 240×135 Rgb565 renderer for the Heltec T114 ST7789 panel.
+//!
+//! Mirrors the content shape of the mono OLED renderer in `display::render`
+//! (same `BoardInfo` / `DashboardCtx` inputs) but lays things out for the
+//! T114's bigger color screen with native font sizes and colored badges.
+//! Each board's `BoardDisplay` impl picks the renderer that matches its
+//! native pixel format — no per-pixel color quantization, no scaling,
+//! no aliasing.
+
+use core::fmt::Write;
+
+use embedded_graphics::mono_font::ascii::{
+    FONT_6X10, FONT_8X13, FONT_8X13_BOLD, FONT_9X15_BOLD, FONT_10X20,
+};
+use embedded_graphics::mono_font::MonoTextStyle;
+use embedded_graphics::pixelcolor::Rgb565;
+use embedded_graphics::prelude::*;
+use embedded_graphics::primitives::{Line, PrimitiveStyle, Rectangle};
+use embedded_graphics::text::renderer::CharacterStyle;
+use embedded_graphics::text::{Alignment, Text};
+use heapless::String;
+
+use super::{qr, Badge, BoardInfo, DashboardCtx, QR_WIDTH_PX, RSSI_HISTORY_LEN};
+use crate::protocol::LoRaBandwidth;
+
+// ── Panel dimensions ──────────────────────────────────────────────────
+
+const W: i32 = 240;
+const H: i32 = 135;
+
+// ── Palette ───────────────────────────────────────────────────────────
+
+const BG: Rgb565 = Rgb565::BLACK;
+const FG: Rgb565 = Rgb565::WHITE;
+const DIM: Rgb565 = Rgb565::new(12, 24, 12); // muted gray
+const ACCENT: Rgb565 = Rgb565::new(8, 30, 31); // bright cyan
+const RX_COLOR: Rgb565 = Rgb565::new(8, 60, 8); // bright green
+const TX_COLOR: Rgb565 = Rgb565::new(31, 16, 8); // amber-red
+const SPARK_COLOR: Rgb565 = Rgb565::new(20, 50, 24); // soft green
+
+// ── Sparkline ────────────────────────────────────────────────────────
+
+const RSSI_MIN: i16 = -120;
+const RSSI_MAX: i16 = 0;
+/// Sentinel: no packet received in this slot. Mirrors `display::NO_SIGNAL`.
+const NO_SIGNAL: i16 = -121;
+
+// ── Public render entry points ────────────────────────────────────────
+
+pub fn blank<D: DrawTarget<Color = Rgb565>>(target: &mut D) {
+    let _ = target.clear(BG);
+}
+
+pub fn splash_learn_more<D: DrawTarget<Color = Rgb565>>(target: &mut D) {
+    let _ = target.clear(BG);
+
+    // QR pinned to the right side, vertically centered. 64×64 fits with
+    // ~36 px headroom top/bottom on the 135-tall panel.
+    let qr_w = QR_WIDTH_PX as i32;
+    let qr_x = W - qr_w - 8;
+    let qr_y = (H - qr_w) / 2;
+    qr::draw(target, Point::new(qr_x, qr_y), FG, BG);
+
+    // Text column to the left of the QR.
+    let col_w = qr_x - 8;
+    let col_center = col_w / 2 + 4;
+
+    let title_style = MonoTextStyle::new(&FONT_10X20, ACCENT);
+    let url_style = MonoTextStyle::new(&FONT_8X13, FG);
+    let caption_style = MonoTextStyle::new(&FONT_6X10, DIM);
+
+    let _ = Text::with_alignment(
+        "DongLoRa",
+        Point::new(col_center, 45),
+        title_style,
+        Alignment::Center,
+    )
+    .draw(target);
+
+    let _ = Text::with_alignment(
+        "donglora.com",
+        Point::new(col_center, 73),
+        url_style,
+        Alignment::Center,
+    )
+    .draw(target);
+
+    let _ = Text::with_alignment(
+        "Scan for docs",
+        Point::new(col_center, 95),
+        caption_style,
+        Alignment::Center,
+    )
+    .draw(target);
+}
+
+pub fn splash_info<D: DrawTarget<Color = Rgb565>>(target: &mut D, info: &BoardInfo<'_>) {
+    let _ = target.clear(BG);
+
+    let title_style = MonoTextStyle::new(&FONT_10X20, ACCENT);
+    let board_style = MonoTextStyle::new(&FONT_9X15_BOLD, FG);
+    let mac_style = MonoTextStyle::new(&FONT_8X13, FG);
+    let small_style = MonoTextStyle::new(&FONT_6X10, DIM);
+
+    // Title at top.
+    let _ = Text::with_alignment(
+        "DongLoRa",
+        Point::new(W / 2, 22),
+        title_style,
+        Alignment::Center,
+    )
+    .draw(target);
+
+    // Board name.
+    let _ = Text::with_alignment(
+        info.name,
+        Point::new(W / 2, 50),
+        board_style,
+        Alignment::Center,
+    )
+    .draw(target);
+
+    // MAC.
+    let _ = Text::with_alignment(
+        info.mac,
+        Point::new(W / 2, 75),
+        mac_style,
+        Alignment::Center,
+    )
+    .draw(target);
+
+    // Version.
+    let mut version_buf: String<24> = String::new();
+    let _ = write!(version_buf, "v{}", info.version);
+    let _ = Text::with_alignment(
+        &version_buf,
+        Point::new(W / 2, 95),
+        small_style,
+        Alignment::Center,
+    )
+    .draw(target);
+
+    // Waiting line.
+    let _ = Text::with_alignment(
+        "Waiting for host...",
+        Point::new(W / 2, 120),
+        small_style,
+        Alignment::Center,
+    )
+    .draw(target);
+}
+
+pub fn dashboard<D: DrawTarget<Color = Rgb565>>(target: &mut D, ctx: &DashboardCtx<'_>) {
+    let _ = target.clear(BG);
+
+    // ── Top bar (badge + radio config) ──────────────────────────
+    let top_h = 24;
+    let badge_w = 38;
+    let (badge_color, badge_text) = match ctx.badge {
+        Badge::Rx => (RX_COLOR, "RX"),
+        Badge::Tx => (TX_COLOR, "TX"),
+    };
+
+    let badge_rect = Rectangle::new(Point::zero(), Size::new(badge_w as u32, top_h as u32));
+    let _ = badge_rect
+        .into_styled(PrimitiveStyle::with_fill(badge_color))
+        .draw(target);
+
+    let mut badge_style = MonoTextStyle::new(&FONT_8X13_BOLD, FG);
+    badge_style.set_background_color(Some(badge_color));
+    let _ = Text::with_alignment(
+        badge_text,
+        Point::new(badge_w / 2, 16),
+        badge_style,
+        Alignment::Center,
+    )
+    .draw(target);
+
+    // Radio config text right of the badge.
+    let cfg_style = MonoTextStyle::new(&FONT_8X13, FG);
+    let mut buf: String<48> = String::new();
+    if let Some(cfg) = ctx.config {
+        let bw_str = bw_label(cfg.bw);
+        let cr_str = cr_label(cfg.cr);
+        let freq_mhz = cfg.freq_hz / 1_000_000;
+        let freq_khz = (cfg.freq_hz % 1_000_000) / 1_000;
+        let _ = write!(
+            buf,
+            "{}.{:03} {} SF{} CR{}",
+            freq_mhz, freq_khz, bw_str, cfg.sf, cr_str
+        );
+    } else {
+        let _ = write!(buf, "Awaiting config");
+    }
+    let _ = Text::with_alignment(
+        &buf,
+        Point::new(W - 4, 16),
+        cfg_style,
+        Alignment::Right,
+    )
+    .draw(target);
+
+    // Separator line under top bar.
+    let _ = Line::new(Point::new(0, top_h + 1), Point::new(W - 1, top_h + 1))
+        .into_styled(PrimitiveStyle::with_stroke(DIM, 1))
+        .draw(target);
+
+    // ── Bottom bar (counters + RSSI) ───────────────────────────
+    let bottom_h = 30;
+    let bottom_top = H - bottom_h;
+    let _ = Line::new(
+        Point::new(0, bottom_top - 1),
+        Point::new(W - 1, bottom_top - 1),
+    )
+    .into_styled(PrimitiveStyle::with_stroke(DIM, 1))
+    .draw(target);
+
+    let stat_style = MonoTextStyle::new(&FONT_8X13, FG);
+
+    let mut rxtx_buf: String<24> = String::new();
+    let _ = write!(
+        rxtx_buf,
+        "RX {} TX {}",
+        compact_count(ctx.rx_count).as_str(),
+        compact_count(ctx.tx_count).as_str()
+    );
+    let _ = Text::with_alignment(
+        &rxtx_buf,
+        Point::new(4, bottom_top + 11),
+        stat_style,
+        Alignment::Left,
+    )
+    .draw(target);
+
+    let mut rssi_buf: String<32> = String::new();
+    match (ctx.last_rssi, ctx.last_snr) {
+        (Some(rssi), Some(snr)) => {
+            let _ = write!(rssi_buf, "{} dBm  SNR {}", rssi, snr);
+        }
+        (Some(rssi), None) => {
+            let _ = write!(rssi_buf, "{} dBm", rssi);
+        }
+        _ => {
+            let _ = write!(rssi_buf, "no signal");
+        }
+    }
+    let _ = Text::with_alignment(
+        &rssi_buf,
+        Point::new(W - 4, bottom_top + 11),
+        stat_style,
+        Alignment::Right,
+    )
+    .draw(target);
+
+    let secondary = MonoTextStyle::new(&FONT_6X10, DIM);
+    let _ = Text::with_alignment(
+        ctx.board.mac,
+        Point::new(W / 2, bottom_top + 25),
+        secondary,
+        Alignment::Center,
+    )
+    .draw(target);
+
+    // ── Sparkline ──────────────────────────────────────────────
+    let spark_top = top_h + 4;
+    let spark_h = (bottom_top - 2) - spark_top;
+    if spark_h > 0 {
+        // 240 wide / 2 px per bar = 120 visible bars (subset of the
+        // 128-slot ring). Matches the mono renderer's
+        // `visible_bars = w / 2` heuristic.
+        let visible_bars = ((W / 2) as usize).min(RSSI_HISTORY_LEN);
+        rssi_sparkline(
+            target,
+            ctx.rssi_history,
+            ctx.tx_history,
+            ctx.rssi_count,
+            ctx.current_slot_rssi,
+            ctx.current_slot_tx,
+            spark_top,
+            spark_h,
+            visible_bars,
+        );
+    }
+}
+
+// ── Helpers ───────────────────────────────────────────────────────────
+
+fn bw_label(bw: LoRaBandwidth) -> &'static str {
+    match bw {
+        LoRaBandwidth::Khz7 => "7.8k",
+        LoRaBandwidth::Khz10 => "10.4k",
+        LoRaBandwidth::Khz15 => "15.6k",
+        LoRaBandwidth::Khz20 => "20.8k",
+        LoRaBandwidth::Khz31 => "31.2k",
+        LoRaBandwidth::Khz41 => "41.7k",
+        LoRaBandwidth::Khz62 => "62.5k",
+        LoRaBandwidth::Khz125 => "125k",
+        LoRaBandwidth::Khz250 => "250k",
+        LoRaBandwidth::Khz500 => "500k",
+        LoRaBandwidth::Khz200 => "200k",
+        LoRaBandwidth::Khz400 => "400k",
+        LoRaBandwidth::Khz800 => "800k",
+        LoRaBandwidth::Khz1600 => "1.6M",
+    }
+}
+
+fn cr_label(cr: crate::protocol::LoRaCodingRate) -> &'static str {
+    match cr {
+        crate::protocol::LoRaCodingRate::Cr4_5 => "5",
+        crate::protocol::LoRaCodingRate::Cr4_6 => "6",
+        crate::protocol::LoRaCodingRate::Cr4_7 => "7",
+        crate::protocol::LoRaCodingRate::Cr4_8 => "8",
+    }
+}
+
+fn compact_count(n: u32) -> String<10> {
+    let mut s: String<10> = String::new();
+    if n > 9_999_999 {
+        let _ = write!(s, "{}M", n / 1_000_000);
+    } else if n > 999_999 {
+        let _ = write!(s, "{}k", n / 1_000);
+    } else {
+        let _ = write!(s, "{}", n);
+    }
+    s
+}
+
+#[allow(clippy::too_many_arguments)]
+fn rssi_sparkline<D: DrawTarget<Color = Rgb565>>(
+    target: &mut D,
+    history: &[i16; RSSI_HISTORY_LEN],
+    tx_history: &[bool; RSSI_HISTORY_LEN],
+    count: usize,
+    current_rssi: i16,
+    current_tx: bool,
+    spark_top: i32,
+    spark_h: i32,
+    visible_bars: usize,
+) {
+    let live = current_rssi > RSSI_MIN || current_tx;
+    let committed = count.min(RSSI_HISTORY_LEN);
+    let hist_slots = if live {
+        committed.min(visible_bars.saturating_sub(1))
+    } else {
+        committed.min(visible_bars)
+    };
+    let total = hist_slots + if live { 1 } else { 0 };
+
+    if total == 0 {
+        return;
+    }
+
+    for i in 0..hist_slots {
+        let idx = if count <= RSSI_HISTORY_LEN {
+            let effective_bars = if live { visible_bars - 1 } else { visible_bars };
+            i + committed.saturating_sub(effective_bars)
+        } else {
+            let start = count - RSSI_HISTORY_LEN;
+            let skip = RSSI_HISTORY_LEN.saturating_sub(if live {
+                visible_bars - 1
+            } else {
+                visible_bars
+            });
+            (start + skip + i) % RSSI_HISTORY_LEN
+        };
+        let is_tx = tx_history[idx];
+        let rssi = history[idx];
+
+        if let Some(bar_h) = bar_height(rssi, is_tx, spark_h) {
+            let x = (visible_bars - total + i) as i32 * 2;
+            draw_bar(target, x, bar_h, is_tx, spark_top, spark_h);
+        }
+    }
+
+    if live {
+        if let Some(bar_h) = bar_height(current_rssi, current_tx, spark_h) {
+            let x = (visible_bars - 1) as i32 * 2;
+            draw_bar(target, x, bar_h, current_tx, spark_top, spark_h);
+        }
+    }
+}
+
+fn bar_height(rssi: i16, is_tx: bool, spark_h: i32) -> Option<i32> {
+    let h = if rssi <= RSSI_MIN || rssi == NO_SIGNAL {
+        if is_tx {
+            spark_h / 3
+        } else {
+            return None;
+        }
+    } else {
+        let clamped = rssi.clamp(RSSI_MIN, RSSI_MAX);
+        ((clamped - RSSI_MIN) as i32 * spark_h) / (RSSI_MAX - RSSI_MIN) as i32
+    };
+    if h == 0 { None } else { Some(h) }
+}
+
+fn draw_bar<D: DrawTarget<Color = Rgb565>>(
+    target: &mut D,
+    x: i32,
+    bar_h: i32,
+    is_tx: bool,
+    spark_top: i32,
+    spark_h: i32,
+) {
+    let y = spark_top + spark_h - bar_h;
+    let color = if is_tx { TX_COLOR } else { SPARK_COLOR };
+    if is_tx {
+        // Hatched bar — every other pixel row — mirrors the mono
+        // renderer's TX visual cue.
+        for row in 0..bar_h {
+            if row % 2 == 0 {
+                let _ = Rectangle::new(Point::new(x, y + row), Size::new(2, 1))
+                    .into_styled(PrimitiveStyle::with_fill(color))
+                    .draw(target);
+            }
+        }
+    } else {
+        let _ = Rectangle::new(Point::new(x, y), Size::new(2, bar_h as u32))
+            .into_styled(PrimitiveStyle::with_fill(color))
+            .draw(target);
+    }
+}

src/driver/mod.rs

@@ -9,10 +9,14 @@ pub mod sh1106;
 #[cfg(any(feature = "lilygo_tbeam_supreme", feature = "lilygo_tbeam"))]
 pub mod axp;
 
-#[cfg(feature = "lilygo_tbeam")]
+#[cfg(any(feature = "lilygo_tbeam", feature = "heltec_mesh_node_t114"))]
 pub mod inverted_pin;
 
+#[cfg(feature = "heltec_mesh_node_t114")]
+pub mod st7789;
+
 #[cfg(any(
+    feature = "heltec_mesh_node_t114",
     feature = "heltec_v3",
     feature = "heltec_v3_uart",
     feature = "heltec_v4",

src/driver/st7789.rs

@@ -0,0 +1,123 @@
+//! ST7789 240×135 IPS TFT driver wrapper for the Heltec Mesh Node T114.
+//!
+//! Wraps `lcd_async::Display<…, models::ST7789, …>` (async fork of
+//! mipidsi) with an in-RAM raw byte framebuffer (240×135 × 2 bytes
+//! Rgb565 BE = 64,800 bytes) and an active-LOW PWM backlight on PWM0.
+//!
+//! Renderers draw into the framebuffer via `lcd_async::raw_framebuf::RawFrameBuf`;
+//! `present()` awaits a single async DMA blit of the entire buffer to
+//! the panel via `panel.show_raw_data(...).await`. The await lets
+//! embassy-nrf's DMA-backed Spim yield the executor for the duration
+//! of the ~65 ms SPI transfer, so the radio task can run alongside
+//! and the SX1262 IRQ handler isn't starved during repaints.
+
+use embassy_nrf::pwm::{DutyCycle, SimplePwm};
+use embedded_graphics::pixelcolor::Rgb565;
+use lcd_async::interface::Interface;
+use lcd_async::models::ST7789;
+use lcd_async::raw_framebuf::RawFrameBuf;
+use lcd_async::Display;
+
+use crate::display::{render_color, BoardDisplay, BoardInfo, DashboardCtx};
+
+/// PWM countertop. Drives the backlight at ~1 kHz (well above flicker).
+pub const BL_MAX: u16 = 1000;
+
+fn bl_bright() -> DutyCycle {
+    // Inverted polarity: HIGH for 0 counts → always LOW → full bright.
+    DutyCycle::inverted(0)
+}
+
+fn bl_dim() -> DutyCycle {
+    // ~80% HIGH → ~20% LOW → 20% brightness.
+    DutyCycle::inverted((BL_MAX * 4) / 5)
+}
+
+#[allow(dead_code)]
+fn bl_off() -> DutyCycle {
+    DutyCycle::inverted(BL_MAX)
+}
+
+// ── Framebuffer ───────────────────────────────────────────────────────
+
+pub const FB_W: usize = 240;
+pub const FB_H: usize = 135;
+/// Bytes for one full Rgb565 frame (2 bytes/pixel, big-endian — matches
+/// what ST7789 expects in 16-bit color mode).
+pub const FB_BYTES: usize = FB_W * FB_H * 2;
+
+// ── St7789Color ───────────────────────────────────────────────────────
+
+pub struct St7789Color<DI, RST>
+where
+    DI: Interface,
+    RST: embedded_hal::digital::OutputPin,
+{
+    panel: Display<DI, ST7789, RST>,
+    backlight: SimplePwm<'static>,
+    fb: &'static mut [u8; FB_BYTES],
+}
+
+impl<DI, RST> St7789Color<DI, RST>
+where
+    DI: Interface,
+    RST: embedded_hal::digital::OutputPin,
+{
+    pub fn new(
+        panel: Display<DI, ST7789, RST>,
+        backlight: SimplePwm<'static>,
+        fb: &'static mut [u8; FB_BYTES],
+    ) -> Self {
+        Self { panel, backlight, fb }
+    }
+
+    /// Wrap the raw byte buffer as a `RawFrameBuf<Rgb565, _>` so
+    /// `embedded-graphics` primitives can draw into it, then run `f`.
+    /// The borrow ends when this returns, freeing `self.fb` for the
+    /// subsequent blit in `present()`.
+    fn with_fb<F: FnOnce(&mut RawFrameBuf<Rgb565, &mut [u8]>)>(&mut self, f: F) {
+        let mut fbuf = RawFrameBuf::<Rgb565, _>::new(&mut self.fb[..], FB_W, FB_H);
+        f(&mut fbuf);
+    }
+}
+
+impl<DI, RST> BoardDisplay for St7789Color<DI, RST>
+where
+    DI: Interface<Word = u8>,
+    RST: embedded_hal::digital::OutputPin,
+{
+    /// Blit the entire framebuffer to the panel via the async SPI
+    /// interface. embassy-nrf's Spim runs the transfer over EasyDMA;
+    /// the `.await` yields the executor for the duration so the radio
+    /// task can process SX1262 IRQs concurrently.
+    async fn present(&mut self) {
+        let _ = self
+            .panel
+            .show_raw_data(0, 0, FB_W as u16, FB_H as u16, self.fb.as_ref())
+            .await;
+    }
+
+    async fn set_bright(&mut self) {
+        self.backlight.set_duty(0, bl_bright());
+    }
+
+    async fn set_dim(&mut self) {
+        self.backlight.set_duty(0, bl_dim());
+    }
+
+    fn render_splash_learn_more(&mut self) {
+        self.with_fb(|fb| render_color::splash_learn_more(fb));
+    }
+
+    fn render_splash_info(&mut self, info: &BoardInfo<'_>) {
+        self.with_fb(|fb| render_color::splash_info(fb, info));
+    }
+
+    fn render_dashboard(&mut self, ctx: &DashboardCtx<'_>) {
+        self.with_fb(|fb| render_color::dashboard(fb, ctx));
+    }
+
+    fn render_blank(&mut self) {
+        self.with_fb(|fb| render_color::blank(fb));
+    }
+}

src/hal/mod.rs

@@ -15,7 +15,11 @@ pub mod esp32s3;
 #[cfg(feature = "lilygo_tbeam")]
 pub mod esp32;
 
-#[cfg(any(feature = "rak_wisblock_4631", feature = "wio_tracker_l1"))]
+#[cfg(any(
+    feature = "heltec_mesh_node_t114",
+    feature = "rak_wisblock_4631",
+    feature = "wio_tracker_l1"
+))]
 pub mod nrf52840;
 
 #[cfg(feature = "waveshare_rp2040_lora")]

src/hal/nrf52840.rs

@@ -13,11 +13,23 @@ bind_interrupts!(pub 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>;
+    // SPIM2 is the second free SPI peripheral on nRF52840. Only used
+    // today by the Heltec T114 (ST7789 TFT panel on a write-only bus
+    // that can't share with the SX1262 on SPIM3 because the pins
+    // differ). Boards that don't use SPI2 don't construct anything
+    // against it and this binding is a no-op for them.
+    SPI2 => embassy_nrf::spim::InterruptHandler<embassy_nrf::peripherals::SPI2>;
 });
 
 // ── MCU-level types ─────────────────────────────────────────────────
 
 pub type SpiBus = embassy_nrf::spim::Spim<'static>;
+// I2C is used by some nRF boards (RAK4631 / Wio Tracker L1 OLED) but not
+// others (T114 uses SPI for the TFT). The `#[allow(dead_code)]` keeps
+// the type available for any board that wants it without per-feature
+// gating; rustc otherwise fires a dead-code lint when the active board
+// doesn't construct one.
+#[allow(dead_code)]
 pub type I2cBus = embassy_nrf::twim::Twim<'static>;
 pub type UsbNrfDriver =
     embassy_nrf::usb::Driver<'static, &'static embassy_nrf::usb::vbus_detect::SoftwareVbusDetect>;
@@ -37,6 +49,8 @@ pub fn share_spi_bus(spi: SpiBus) -> &'static embassy_sync::mutex::Mutex<NoopRaw
 ///
 /// Every nRF52840 Twim user needs a `&'static mut [u8]` buffer.
 /// This provides one via StaticCell so board files don't repeat the pattern.
+/// Unused on nRF boards that don't expose I2C (e.g. T114 uses SPI for the TFT).
+#[allow(dead_code)]
 pub fn alloc_i2c_buffer() -> &'static mut [u8; 256] {
     static TWIM_BUF: StaticCell<[u8; 256]> = StaticCell::new();
     TWIM_BUF.init([0u8; 256])

src/main.rs

@@ -46,7 +46,7 @@ use crate::protocol::{cap, Info, MAX_MCU_UID_LEN, MAX_RADIO_UID_LEN};
 
 #[cfg(not(test))]
 cfg_if::cfg_if! {
-    if #[cfg(any(feature = "rak_wisblock_4631", feature = "wio_tracker_l1", feature = "waveshare_rp2040_lora"))] {
+    if #[cfg(any(feature = "heltec_mesh_node_t114", feature = "rak_wisblock_4631", feature = "wio_tracker_l1", feature = "waveshare_rp2040_lora"))] {
         use defmt_rtt as _;
         use panic_probe as _;
     } else if #[cfg(any(feature = "heltec_v3", feature = "heltec_v3_uart", feature = "heltec_v4", feature = "elecrow_thinknode_m2", feature = "lilygo_tbeam_supreme", feature = "lilygo_tbeam"))] {
@@ -71,7 +71,7 @@ static mut INFO: Option<Info> = None;
 
 #[cfg(not(test))]
 cfg_if::cfg_if! {
-    if #[cfg(any(feature = "rak_wisblock_4631", feature = "wio_tracker_l1", feature = "waveshare_rp2040_lora"))] {
+    if #[cfg(any(feature = "heltec_mesh_node_t114", feature = "rak_wisblock_4631", feature = "wio_tracker_l1", feature = "waveshare_rp2040_lora"))] {
         #[embassy_executor::main]
         async fn main(spawner: Spawner) {
             run(spawner).await;
@@ -93,7 +93,7 @@ async fn run(spawner: Spawner) {
     // of the RTT log. Critical for soak-debugging silent crash-reboots:
     // a self-rebooting firmware otherwise looks like the log just
     // restarted with no explanation. nRF52840-only.
-    #[cfg(any(feature = "rak_wisblock_4631", feature = "wio_tracker_l1"))]
+    #[cfg(any(feature = "heltec_mesh_node_t114", feature = "rak_wisblock_4631", feature = "wio_tracker_l1"))]
     crate::hal::nrf52840::dump_reset_reason();
 
     let parts = board.into_parts();