Struct DmaFrameBuffer

#[repr(C)]
pub struct DmaFrameBuffer<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> { /* private fields */ }

DMA-compatible framebuffer for HUB75 LED panels.

This is a framebuffer implementation that:

• Manages multiple frames for Binary Code Modulation (BCM)
• Provides DMA-compatible memory layout
• Implements the embedded-graphics DrawTarget trait

Type Parameters

• ROWS: Total number of rows in the panel
• COLS: Number of columns in the panel
• NROWS: Number of rows per scan (typically half of ROWS)
• BITS: Color depth (1-8 bits)
• FRAME_COUNT: Number of frames used for Binary Code Modulation

Helper Functions

Use these functions to compute the correct values:

• esp_hub75::compute_frame_count(BITS): Computes the required number of frames
• esp_hub75::compute_rows(ROWS): Computes the number of rows per scan

Memory Layout

The buffer is aligned to ensure efficient DMA transfers and contains:

• A 64-bit alignment field
• An array of frames, each containing the full panel data

Implementations

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

pub fn new() -> Self

Create a new, ready-to-use framebuffer.

This creates a new framebuffer and automatically formats it with proper timing signals. The framebuffer is immediately ready for pixel operations and DMA transfers.

Panics

Panics if BITS is greater than 8, as only 1-8 bit color depths are supported.

Example

use hub75_framebuffer::{Color,plain::DmaFrameBuffer,compute_rows,compute_frame_count};

const ROWS: usize = 32;
const COLS: usize = 64;
const BITS: u8 = 3; // Color depth (8 brightness levels, 7 frames)
const NROWS: usize = compute_rows(ROWS); // Number of rows per scan
const FRAME_COUNT: usize = compute_frame_count(BITS); // Number of frames for BCM

let mut framebuffer = DmaFrameBuffer::<ROWS, COLS, NROWS, BITS, FRAME_COUNT>::new();
// No need to call format() - framebuffer is ready to use!

pub fn format(&mut self)

Perform full formatting of the framebuffer with timing and control signals.

This sets up all the timing and control signals needed for proper HUB75 operation. This is automatically called by new(), so you typically don’t need to call this unless you want to completely reinitialize the framebuffer.

Example

use hub75_framebuffer::{Color,plain::DmaFrameBuffer,compute_rows,compute_frame_count};

const ROWS: usize = 32;
const COLS: usize = 64;
const BITS: u8 = 3; // Color depth (8 brightness levels, 7 frames)
const NROWS: usize = compute_rows(ROWS); // Number of rows per scan
const FRAME_COUNT: usize = compute_frame_count(BITS); // Number of frames for BCM

let mut framebuffer = DmaFrameBuffer::<ROWS, COLS, NROWS, BITS, FRAME_COUNT>::new();
framebuffer.format(); // Reinitialize if needed

pub fn erase(&mut self)

Fast erase operation that clears all pixel data while preserving timing signals.

This is much faster than format() when you just want to clear the display since it preserves all the timing and control signals that are already set up. Use this for clearing between frames or when you want to start drawing fresh content.

Example

use hub75_framebuffer::{Color,plain::DmaFrameBuffer,compute_rows,compute_frame_count};

const ROWS: usize = 32;
const COLS: usize = 64;
const BITS: u8 = 3; // Color depth (8 brightness levels, 7 frames)
const NROWS: usize = compute_rows(ROWS); // Number of rows per scan
const FRAME_COUNT: usize = compute_frame_count(BITS); // Number of frames for BCM

let mut framebuffer = DmaFrameBuffer::<ROWS, COLS, NROWS, BITS, FRAME_COUNT>::new();
framebuffer.erase();

pub fn set_pixel(&mut self, p: Point, color: Color)

Set a pixel in the framebuffer.

Example

use hub75_framebuffer::{Color,plain::DmaFrameBuffer,compute_rows,compute_frame_count};
use embedded_graphics::prelude::*;

const ROWS: usize = 32;
const COLS: usize = 64;
const BITS: u8 = 3; // Color depth (8 brightness levels, 7 frames)
const NROWS: usize = compute_rows(ROWS); // Number of rows per scan
const FRAME_COUNT: usize = compute_frame_count(BITS); // Number of frames for BCM

let mut framebuffer = DmaFrameBuffer::<ROWS, COLS, NROWS, BITS, FRAME_COUNT>::new();
framebuffer.set_pixel(Point::new(10, 10), Color::RED);

Trait Implementations

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> Clone for DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

fn clone(&self) -> DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> Debug for DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> Default for DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

fn default() -> Self

Returns the “default value” for a type.

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> DrawTarget for DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

type Color = Rgb888

The pixel color type the targetted display supports.

type Error = Infallible

Error type to return when a drawing operation fails.

fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>

where I: IntoIterator<Item = Pixel<Self::Color>>,

Draw individual pixels to the display without a defined order.

fn fill_contiguous<I>( &mut self, area: &Rectangle, colors: I, ) -> Result<(), Self::Error>

where I: IntoIterator<Item = Self::Color>,

Fill a given area with an iterator providing a contiguous stream of pixel colors.

fn fill_solid( &mut self, area: &Rectangle, color: Self::Color, ) -> Result<(), Self::Error>

Fill a given area with a solid color.

fn clear(&mut self, color: Self::Color) -> Result<(), Self::Error>

Fill the entire display with a solid color.

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> FrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT> for &mut DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

fn get_word_size(&self) -> WordSize

Returns the word size configuration for this framebuffer

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> FrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT> for DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

fn get_word_size(&self) -> WordSize

Returns the word size configuration for this framebuffer

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> OriginDimensions for &mut DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

fn size(&self) -> Size

Returns the size of the bounding box.

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> OriginDimensions for DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

fn size(&self) -> Size

Returns the size of the bounding box.

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> ReadBuffer for &mut DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

type Word = u8

unsafe fn read_buffer(&self) -> (*const u8, usize)

Provide a buffer usable for DMA reads.

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> ReadBuffer for DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>

type Word = u8

unsafe fn read_buffer(&self) -> (*const u8, usize)

Provide a buffer usable for DMA reads.

impl<const ROWS: usize, const COLS: usize, const NROWS: usize, const BITS: u8, const FRAME_COUNT: usize> Copy for DmaFrameBuffer<ROWS, COLS, NROWS, BITS, FRAME_COUNT>