esp-wroverkit: add framebuffer on the heap

Author: georgik

docs/README.md

@@ -19,6 +19,21 @@ cd esp32-s3-box-3-minimal
 cargo run --release
 ```
 
+### ESP32-C6-LCD-1.47 Waveshare
+
+[Rust Bare Metal no_std](https://developer.espressif.com/blog/2025/02/rust-esp-hal-beta/) with [Bevy ECS no_std](https://github.com/bevyengine/bevy/issues/15460) on 1.47 inch [ESP32-C6 LCD Waheshare](https://www.waveshare.com/esp32-c6-lcd-1.47.htm) with DMA and framebuffer - [Conway's Game of Life](https://github.com/georgik/esp32-conways-game-of-life-rs/tree/main/esp32-c6-waveshare-1_47):
+
+<video src="https://github.com/user-attachments/assets/e9d48ff7-b14c-4874-9521-fe59e915bc76" controls width="640">
+View the video [here](https://github.com/user-attachments/assets/e9d48ff7-b14c-4874-9521-fe59e915bc76).
+</video>
+
+The implementation is based on Rust no\_std and Bevy 0.15 no\_std, plus mipidsi crate
+
+```
+cd esp32-c6-waveshare-1_47
+cargo run --release
+```
+
 ### ESP32-S3-BOX-3
 
 ![ESP32 Conways Game of Life in Rust - ESP32-S3-BOX-3 with Bevy ECS](esp32-s3-box-3-conway.jpg)
@@ -43,21 +58,6 @@ cd esp32-s3-box-3
 cargo run --release
 ```
 
-### ESP32-C6-LCD-1.47 Waveshare
-
-[Rust Bare Metal no_std](https://developer.espressif.com/blog/2025/02/rust-esp-hal-beta/) with [Bevy ECS no_std](https://github.com/bevyengine/bevy/issues/15460) on 1.47 inch [ESP32-C6 LCD Waheshare](https://www.waveshare.com/esp32-c6-lcd-1.47.htm) with DMA and framebuffer - [Conway's Game of Life](https://github.com/georgik/esp32-conways-game-of-life-rs/tree/main/esp32-c6-waveshare-1_47):
-
-<video src="https://github.com/user-attachments/assets/e9d48ff7-b14c-4874-9521-fe59e915bc76" controls width="640">
-View the video [here](https://github.com/user-attachments/assets/e9d48ff7-b14c-4874-9521-fe59e915bc76).
-</video>
-
-The implementation is based on Rust no\_std and Bevy 0.15 no\_std, plus mipidsi crate
-
-```
-cd esp32-c6-waveshare-1_47
-cargo run --release
-```
-
 ### ESP32-C3-LCDKit
 
 Limitation: Framebuffer fits only to 240x190 pixels. Might be cause by allocation on stack instead of heap.
@@ -82,13 +82,11 @@ python3 -m http.server
 
 This board is no longer in production, yet it's still used by many developers.
 
+![ESP32 Conways Game of Life in Rust - ESP-WROVER-KIT with Bevy ECS](esp32-wrover-kit.jpg)
+
 The implementation is based on Rust no\_std, using mipidsi crate and Bevy ECS.
 It requires es-rs toolchain for ESP32-S3 version at [least 1.85](https://github.com/esp-rs/rust-build/releases/tag/v1.85.0.0), because of edition 2024.
 
-Limitation: Graphical buffer is limited to 320x100 pixels due to memory issue.
-PSRAM should work, but for some reason the buffer is not allocated there.
-Some previous examples were working with PSRAM fine, it needs further investigation
-
 Installation of the toolchain:
 
 ```

docs/esp32-wrover-kit.jpg

@@ -55,11 +55,51 @@ type MyDisplay = mipidsi::Display<
 
 // --- LCD Resolution and FrameBuffer Type Aliases ---
 const LCD_H_RES: usize = 320;
-const LCD_V_RES: usize = 100;
+const LCD_V_RES: usize = 240;
 const LCD_BUFFER_SIZE: usize = LCD_H_RES * LCD_V_RES;
 
+use embedded_graphics::pixelcolor::PixelColor;
+use embedded_graphics_framebuf::backends::FrameBufferBackend;
+
+/// A wrapper around a boxed array that implements FrameBufferBackend.
+/// This allows the framebuffer to be allocated on the heap.
+pub struct HeapBuffer<C: PixelColor, const N: usize>(Box<[C; N]>);
+
+impl<C: PixelColor, const N: usize> HeapBuffer<C, N> {
+    pub fn new(data: Box<[C; N]>) -> Self {
+        Self(data)
+    }
+}
+
+impl<C: PixelColor, const N: usize> core::ops::Deref for HeapBuffer<C, N> {
+    type Target = [C; N];
+    fn deref(&self) -> &Self::Target {
+        &*self.0
+    }
+}
+
+impl<C: PixelColor, const N: usize> core::ops::DerefMut for HeapBuffer<C, N> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut *self.0
+    }
+}
+
+impl<C: PixelColor, const N: usize> FrameBufferBackend for HeapBuffer<C, N> {
+    type Color = C;
+    fn set(&mut self, index: usize, color: Self::Color) {
+        self.0[index] = color;
+    }
+    fn get(&self, index: usize) -> Self::Color {
+        self.0[index]
+    }
+    fn nr_elements(&self) -> usize {
+        N
+    }
+}
+
+
 // We want our pixels stored as Rgb565.
-type FbBuffer = [Rgb565; LCD_BUFFER_SIZE];
+type FbBuffer = HeapBuffer<Rgb565, LCD_BUFFER_SIZE>;
 // Define a type alias for the complete FrameBuf.
 type MyFrameBuf = FrameBuf<Rgb565, FbBuffer>;
 
@@ -70,13 +110,15 @@ struct FrameBufferResource {
 
 impl FrameBufferResource {
     fn new() -> Self {
-        // Allocate the framebuffer data as an owned array of Rgb565.
-        let fb_data: FbBuffer = *Box::new([Rgb565::BLACK; LCD_BUFFER_SIZE]);
-        let frame_buf = MyFrameBuf::new(fb_data, LCD_H_RES, LCD_V_RES);
+        // Allocate the framebuffer data on the heap.
+        let fb_data: Box<[Rgb565; LCD_BUFFER_SIZE]> = Box::new([Rgb565::BLACK; LCD_BUFFER_SIZE]);
+        let heap_buffer = HeapBuffer::new(fb_data);
+        let frame_buf = MyFrameBuf::new(heap_buffer, LCD_H_RES, LCD_V_RES);
         Self { frame_buf }
     }
 }
 
+
 // --- Game of Life Definitions ---
 // Now each cell is a u8 (0 means dead; >0 indicates age)
 const GRID_WIDTH: usize = 64;