Add LTDC example for STM32U5G9J-DK2 demo board

examples/stm32u5/Cargo.toml

@@ -21,6 +21,8 @@ cortex-m-rt = "0.7.0"
 embedded-hal = "0.2.6"
 panic-probe = { version = "0.3", features = ["print-defmt"] }
 heapless = { version = "0.8", default-features = false }
+embedded-graphics = { version = "0.8.1" }
+tinybmp = { version = "0.6.0" }
 
 micromath = "2.0.0"
 

examples/stm32u5/src/bin/ltdc.rs

@@ -0,0 +1,462 @@
+#![no_std]
+#![no_main]
+#![macro_use]
+#![allow(static_mut_refs)]
+
+/// This example was derived from examples\stm32h735\src\bin\ltdc.rs
+/// It demonstrates the LTDC lcd display peripheral and was tested on an STM32U5G9J-DK2 demo board (embassy-stm32 feature "stm32u5g9zj" and probe-rs chip "STM32U5G9ZJTxQ")
+///
+use bouncy_box::BouncyBox;
+use defmt::{info, unwrap};
+use embassy_executor::Spawner;
+use embassy_stm32::gpio::{Level, Output, Speed};
+use embassy_stm32::ltdc::{self, Ltdc, LtdcConfiguration, LtdcLayer, LtdcLayerConfig, PolarityActive, PolarityEdge};
+use embassy_stm32::{bind_interrupts, peripherals};
+use embassy_time::{Duration, Timer};
+use embedded_graphics::draw_target::DrawTarget;
+use embedded_graphics::geometry::{OriginDimensions, Point, Size};
+use embedded_graphics::image::Image;
+use embedded_graphics::pixelcolor::raw::RawU24;
+use embedded_graphics::pixelcolor::Rgb888;
+use embedded_graphics::prelude::*;
+use embedded_graphics::primitives::Rectangle;
+use embedded_graphics::Pixel;
+use heapless::{Entry, FnvIndexMap};
+use tinybmp::Bmp;
+use {defmt_rtt as _, panic_probe as _};
+
+const DISPLAY_WIDTH: usize = 800;
+const DISPLAY_HEIGHT: usize = 480;
+const MY_TASK_POOL_SIZE: usize = 2;
+
+// the following two display buffers consume 261120 bytes that just about fits into axis ram found on the mcu
+pub static mut FB1: [TargetPixelType; DISPLAY_WIDTH * DISPLAY_HEIGHT] = [0; DISPLAY_WIDTH * DISPLAY_HEIGHT];
+pub static mut FB2: [TargetPixelType; DISPLAY_WIDTH * DISPLAY_HEIGHT] = [0; DISPLAY_WIDTH * DISPLAY_HEIGHT];
+
+bind_interrupts!(struct Irqs {
+    LTDC => ltdc::InterruptHandler<peripherals::LTDC>;
+});
+
+const NUM_COLORS: usize = 256;
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    let p = rcc_setup::stm32u5g9zj_init();
+
+    // enable ICACHE
+    embassy_stm32::pac::ICACHE.cr().write(|w| {
+        w.set_en(true);
+    });
+
+    // blink the led on another task
+    let led = Output::new(p.PD2, Level::High, Speed::Low);
+    unwrap!(spawner.spawn(led_task(led)));
+
+    // numbers from STM32U5G9J-DK2.ioc
+    const RK050HR18H_HSYNC: u16 = 5; // Horizontal synchronization
+    const RK050HR18H_HBP: u16 = 8; // Horizontal back porch
+    const RK050HR18H_HFP: u16 = 8; // Horizontal front porch
+    const RK050HR18H_VSYNC: u16 = 5; // Vertical synchronization
+    const RK050HR18H_VBP: u16 = 8; // Vertical back porch
+    const RK050HR18H_VFP: u16 = 8; // Vertical front porch
+
+    // NOTE: all polarities have to be reversed with respect to the STM32U5G9J-DK2 CubeMX parametrization
+    let ltdc_config = LtdcConfiguration {
+        active_width: DISPLAY_WIDTH as _,
+        active_height: DISPLAY_HEIGHT as _,
+        h_back_porch: RK050HR18H_HBP,
+        h_front_porch: RK050HR18H_HFP,
+        v_back_porch: RK050HR18H_VBP,
+        v_front_porch: RK050HR18H_VFP,
+        h_sync: RK050HR18H_HSYNC,
+        v_sync: RK050HR18H_VSYNC,
+        h_sync_polarity: PolarityActive::ActiveHigh,
+        v_sync_polarity: PolarityActive::ActiveHigh,
+        data_enable_polarity: PolarityActive::ActiveHigh,
+        pixel_clock_polarity: PolarityEdge::RisingEdge,
+    };
+
+    info!("init ltdc");
+    let mut ltdc_de = Output::new(p.PD6, Level::Low, Speed::High);
+    let mut ltdc_disp_ctrl = Output::new(p.PE4, Level::Low, Speed::High);
+    let mut ltdc_bl_ctrl = Output::new(p.PE6, Level::Low, Speed::High);
+    let mut ltdc = Ltdc::new_with_pins(
+        p.LTDC, // PERIPHERAL
+        Irqs,   // IRQS
+        p.PD3,  // CLK
+        p.PE0,  // HSYNC
+        p.PD13, // VSYNC
+        p.PB9,  // B0
+        p.PB2,  // B1
+        p.PD14, // B2
+        p.PD15, // B3
+        p.PD0,  // B4
+        p.PD1,  // B5
+        p.PE7,  // B6
+        p.PE8,  // B7
+        p.PC8,  // G0
+        p.PC9,  // G1
+        p.PE9,  // G2
+        p.PE10, // G3
+        p.PE11, // G4
+        p.PE12, // G5
+        p.PE13, // G6
+        p.PE14, // G7
+        p.PC6,  // R0
+        p.PC7,  // R1
+        p.PE15, // R2
+        p.PD8,  // R3
+        p.PD9,  // R4
+        p.PD10, // R5
+        p.PD11, // R6
+        p.PD12, // R7
+    );
+    ltdc.init(&ltdc_config);
+    ltdc_de.set_low();
+    ltdc_bl_ctrl.set_high();
+    ltdc_disp_ctrl.set_high();
+
+    // we only need to draw on one layer for this example (not to be confused with the double buffer)
+    info!("enable bottom layer");
+    let layer_config = LtdcLayerConfig {
+        pixel_format: ltdc::PixelFormat::L8, // 1 byte per pixel
+        layer: LtdcLayer::Layer1,
+        window_x0: 0,
+        window_x1: DISPLAY_WIDTH as _,
+        window_y0: 0,
+        window_y1: DISPLAY_HEIGHT as _,
+    };
+
+    let ferris_bmp: Bmp<Rgb888> = Bmp::from_slice(include_bytes!("./ferris.bmp")).unwrap();
+    let color_map = build_color_lookup_map(&ferris_bmp);
+    let clut = build_clut(&color_map);
+
+    // enable the bottom layer with a 256 color lookup table
+    ltdc.init_layer(&layer_config, Some(&clut));
+
+    // Safety: the DoubleBuffer controls access to the statically allocated frame buffers
+    // and it is the only thing that mutates their content
+    let mut double_buffer = DoubleBuffer::new(
+        unsafe { FB1.as_mut() },
+        unsafe { FB2.as_mut() },
+        layer_config,
+        color_map,
+    );
+
+    // this allows us to perform some simple animation for every frame
+    let mut bouncy_box = BouncyBox::new(
+        ferris_bmp.bounding_box(),
+        Rectangle::new(Point::zero(), Size::new(DISPLAY_WIDTH as u32, DISPLAY_HEIGHT as u32)),
+        2,
+    );
+
+    loop {
+        // cpu intensive drawing to the buffer that is NOT currently being copied to the LCD screen
+        double_buffer.clear();
+        let position = bouncy_box.next_point();
+        let ferris = Image::new(&ferris_bmp, position);
+        unwrap!(ferris.draw(&mut double_buffer));
+
+        // perform async dma data transfer to the lcd screen
+        unwrap!(double_buffer.swap(&mut ltdc).await);
+    }
+}
+
+/// builds the color look-up table from all unique colors found in the bitmap. This should be a 256 color indexed bitmap to work.
+fn build_color_lookup_map(bmp: &Bmp<Rgb888>) -> FnvIndexMap<u32, u8, NUM_COLORS> {
+    let mut color_map: FnvIndexMap<u32, u8, NUM_COLORS> = heapless::FnvIndexMap::new();
+    let mut counter: u8 = 0;
+
+    // add black to position 0
+    color_map.insert(Rgb888::new(0, 0, 0).into_storage(), counter).unwrap();
+    counter += 1;
+
+    for Pixel(_point, color) in bmp.pixels() {
+        let raw = color.into_storage();
+        if let Entry::Vacant(v) = color_map.entry(raw) {
+            v.insert(counter).expect("more than 256 colors detected");
+            counter += 1;
+        }
+    }
+    color_map
+}
+
+/// builds the color look-up table from the color map provided
+fn build_clut(color_map: &FnvIndexMap<u32, u8, NUM_COLORS>) -> [ltdc::RgbColor; NUM_COLORS] {
+    let mut clut = [ltdc::RgbColor::default(); NUM_COLORS];
+    for (color, index) in color_map.iter() {
+        let color = Rgb888::from(RawU24::new(*color));
+        clut[*index as usize] = ltdc::RgbColor {
+            red: color.r(),
+            green: color.g(),
+            blue: color.b(),
+        };
+    }
+
+    clut
+}
+
+#[embassy_executor::task(pool_size = MY_TASK_POOL_SIZE)]
+async fn led_task(mut led: Output<'static>) {
+    let mut counter = 0;
+    loop {
+        info!("blink: {}", counter);
+        counter += 1;
+
+        // on
+        led.set_low();
+        Timer::after(Duration::from_millis(50)).await;
+
+        // off
+        led.set_high();
+        Timer::after(Duration::from_millis(450)).await;
+    }
+}
+
+pub type TargetPixelType = u8;
+
+// A simple double buffer
+pub struct DoubleBuffer {
+    buf0: &'static mut [TargetPixelType],
+    buf1: &'static mut [TargetPixelType],
+    is_buf0: bool,
+    layer_config: LtdcLayerConfig,
+    color_map: FnvIndexMap<u32, u8, NUM_COLORS>,
+}
+
+impl DoubleBuffer {
+    pub fn new(
+        buf0: &'static mut [TargetPixelType],
+        buf1: &'static mut [TargetPixelType],
+        layer_config: LtdcLayerConfig,
+        color_map: FnvIndexMap<u32, u8, NUM_COLORS>,
+    ) -> Self {
+        Self {
+            buf0,
+            buf1,
+            is_buf0: true,
+            layer_config,
+            color_map,
+        }
+    }
+
+    pub fn current(&mut self) -> (&FnvIndexMap<u32, u8, NUM_COLORS>, &mut [TargetPixelType]) {
+        if self.is_buf0 {
+            (&self.color_map, self.buf0)
+        } else {
+            (&self.color_map, self.buf1)
+        }
+    }
+
+    pub async fn swap<T: ltdc::Instance>(&mut self, ltdc: &mut Ltdc<'_, T>) -> Result<(), ltdc::Error> {
+        let (_, buf) = self.current();
+        let frame_buffer = buf.as_ptr();
+        self.is_buf0 = !self.is_buf0;
+        ltdc.set_buffer(self.layer_config.layer, frame_buffer as *const _).await
+    }
+
+    /// Clears the buffer
+    pub fn clear(&mut self) {
+        let (color_map, buf) = self.current();
+        let black = Rgb888::new(0, 0, 0).into_storage();
+        let color_index = color_map.get(&black).expect("no black found in the color map");
+
+        for a in buf.iter_mut() {
+            *a = *color_index; // solid black
+        }
+    }
+}
+
+// Implement DrawTarget for
+impl DrawTarget for DoubleBuffer {
+    type Color = Rgb888;
+    type Error = ();
+
+    /// Draw a pixel
+    fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
+    where
+        I: IntoIterator<Item = Pixel<Self::Color>>,
+    {
+        let size = self.size();
+        let width = size.width as i32;
+        let height = size.height as i32;
+        let (color_map, buf) = self.current();
+
+        for pixel in pixels {
+            let Pixel(point, color) = pixel;
+
+            if point.x >= 0 && point.y >= 0 && point.x < width && point.y < height {
+                let index = point.y * width + point.x;
+                let raw_color = color.into_storage();
+
+                match color_map.get(&raw_color) {
+                    Some(x) => {
+                        buf[index as usize] = *x;
+                    }
+                    None => panic!("color not found in color map: {}", raw_color),
+                };
+            } else {
+                // Ignore invalid points
+            }
+        }
+
+        Ok(())
+    }
+}
+
+impl OriginDimensions for DoubleBuffer {
+    /// Return the size of the display
+    fn size(&self) -> Size {
+        Size::new(
+            (self.layer_config.window_x1 - self.layer_config.window_x0) as _,
+            (self.layer_config.window_y1 - self.layer_config.window_y0) as _,
+        )
+    }
+}
+
+mod rcc_setup {
+
+    use embassy_stm32::rcc;
+    use embassy_stm32::time::Hertz;
+    use embassy_stm32::{Config, Peripherals};
+
+    /// Sets up clocks for the stm32u5g9zj mcu
+    /// change this if you plan to use a different microcontroller
+    pub fn stm32u5g9zj_init() -> Peripherals {
+        // setup power and clocks for an STM32U5G9J-DK2 run from an external 16 Mhz external oscillator
+        let mut config = Config::default();
+        config.rcc.hse = Some(rcc::Hse {
+            freq: Hertz(16_000_000),
+            mode: rcc::HseMode::Oscillator,
+        });
+        config.rcc.pll1 = Some(rcc::Pll {
+            source: rcc::PllSource::HSE,
+            prediv: rcc::PllPreDiv::DIV1,
+            mul: rcc::PllMul::MUL10,
+            divp: None,
+            divq: None,
+            divr: Some(rcc::PllDiv::DIV1),
+        });
+        config.rcc.sys = rcc::Sysclk::PLL1_R; // 160 Mhz
+        config.rcc.pll3 = Some(rcc::Pll {
+            source: rcc::PllSource::HSE,
+            prediv: rcc::PllPreDiv::DIV4, // PLL_M
+            mul: rcc::PllMul::MUL125,     // PLL_N
+            divp: None,
+            divq: None,
+            divr: Some(rcc::PllDiv::DIV20),
+        });
+        config.rcc.mux.ltdcsel = rcc::mux::Ltdcsel::PLL3_R; // 25 MHz
+        embassy_stm32::init(config)
+    }
+}
+
+mod bouncy_box {
+    use embedded_graphics::geometry::Point;
+    use embedded_graphics::primitives::Rectangle;
+
+    enum Direction {
+        DownLeft,
+        DownRight,
+        UpLeft,
+        UpRight,
+    }
+
+    pub struct BouncyBox {
+        direction: Direction,
+        child_rect: Rectangle,
+        parent_rect: Rectangle,
+        current_point: Point,
+        move_by: usize,
+    }
+
+    // This calculates the coordinates of a chile rectangle bounced around inside a parent bounded box
+    impl BouncyBox {
+        pub fn new(child_rect: Rectangle, parent_rect: Rectangle, move_by: usize) -> Self {
+            let center_box = parent_rect.center();
+            let center_img = child_rect.center();
+            let current_point = Point::new(center_box.x - center_img.x / 2, center_box.y - center_img.y / 2);
+            Self {
+                direction: Direction::DownRight,
+                child_rect,
+                parent_rect,
+                current_point,
+                move_by,
+            }
+        }
+
+        pub fn next_point(&mut self) -> Point {
+            let direction = &self.direction;
+            let img_height = self.child_rect.size.height as i32;
+            let box_height = self.parent_rect.size.height as i32;
+            let img_width = self.child_rect.size.width as i32;
+            let box_width = self.parent_rect.size.width as i32;
+            let move_by = self.move_by as i32;
+
+            match direction {
+                Direction::DownLeft => {
+                    self.current_point.x -= move_by;
+                    self.current_point.y += move_by;
+
+                    let x_out_of_bounds = self.current_point.x < 0;
+                    let y_out_of_bounds = (self.current_point.y + img_height) > box_height;
+
+                    if x_out_of_bounds && y_out_of_bounds {
+                        self.direction = Direction::UpRight
+                    } else if x_out_of_bounds && !y_out_of_bounds {
+                        self.direction = Direction::DownRight
+                    } else if !x_out_of_bounds && y_out_of_bounds {
+                        self.direction = Direction::UpLeft
+                    }
+                }
+                Direction::DownRight => {
+                    self.current_point.x += move_by;
+                    self.current_point.y += move_by;
+
+                    let x_out_of_bounds = (self.current_point.x + img_width) > box_width;
+                    let y_out_of_bounds = (self.current_point.y + img_height) > box_height;
+
+                    if x_out_of_bounds && y_out_of_bounds {
+                        self.direction = Direction::UpLeft
+                    } else if x_out_of_bounds && !y_out_of_bounds {
+                        self.direction = Direction::DownLeft
+                    } else if !x_out_of_bounds && y_out_of_bounds {
+                        self.direction = Direction::UpRight
+                    }
+                }
+                Direction::UpLeft => {
+                    self.current_point.x -= move_by;
+                    self.current_point.y -= move_by;
+
+                    let x_out_of_bounds = self.current_point.x < 0;
+                    let y_out_of_bounds = self.current_point.y < 0;
+
+                    if x_out_of_bounds && y_out_of_bounds {
+                        self.direction = Direction::DownRight
+                    } else if x_out_of_bounds && !y_out_of_bounds {
+                        self.direction = Direction::UpRight
+                    } else if !x_out_of_bounds && y_out_of_bounds {
+                        self.direction = Direction::DownLeft
+                    }
+                }
+                Direction::UpRight => {
+                    self.current_point.x += move_by;
+                    self.current_point.y -= move_by;
+
+                    let x_out_of_bounds = (self.current_point.x + img_width) > box_width;
+                    let y_out_of_bounds = self.current_point.y < 0;
+
+                    if x_out_of_bounds && y_out_of_bounds {
+                        self.direction = Direction::DownLeft
+                    } else if x_out_of_bounds && !y_out_of_bounds {
+                        self.direction = Direction::UpLeft
+                    } else if !x_out_of_bounds && y_out_of_bounds {
+                        self.direction = Direction::DownRight
+                    }
+                }
+            }
+
+            self.current_point
+        }
+    }
+}