ESP-HUB75

A no-std Rust driver for HUB75-style LED matrix panels on ESP32-series microcontrollers. HUB75 is a standard interface for driving large, bright, and colorful RGB LED displays, commonly used in digital signage and art installations.

This library provides a high-performance implementation that uses Direct Memory Access (DMA) to drive the display with minimal CPU overhead. It is designed to work with a variety of ESP32 models, using the most efficient peripheral available on each chip:

• ESP32-S3: Uses the LCD_CAM peripheral
• ESP32-C6: Uses the PARL_IO peripheral
• ESP32: Uses the I2S peripheral in parallel mode

The driver is built on top of the embedded-graphics crate, allowing you to easily draw shapes, text, and images on the display. It also uses a zero-copy framebuffer for efficient memory usage.

Hardware Requirements

• An ESP32-series microcontroller (ESP32, ESP32-S3, or ESP32-C6)
• A HUB75 LED matrix panel
• A 5V power supply capable of providing several amps of current
• A 3.3V to 5V level shifter (e.g., 74HCT245) is highly recommended

Note: The ESP32 operates at 3.3V, while HUB75 panels require 5V logic signals. While it may sometimes work without one, using a level shifter ensures reliable operation and prevents damage to your hardware.

Pin Configurations

This driver supports two types of HUB75 pin configurations, which you can select based on your hardware setup:

• Hub75Pins16 (Direct Drive): This is the standard configuration where the row address lines are sent with every pixel. It requires more GPIO pins but works with any standard HUB75 panel.

• Hub75Pins8 (Latched): This configuration is for controller boards that include an external 74HC574-style latch for the row address lines. This is more memory-efficient and requires fewer GPIO pins. For more details on the required circuit, see the hub75-framebuffer crate's documentation or its GitHub repository.

Examples

The following examples demonstrate how to use this crate with different ESP32 variants.

ESP32-S3 (LCD_CAM Interface)

• examples/hello_lcd_cam - Displays "Hello, World!".
• examples/lcd_cam.rs - Shows a color gradient and stats.
• examples/lcd_cam_tiled.rs - uses 4 64x32 panels in a 2x2 configuration to show a color gradient and stats

ESP32-C6 (PARL_IO Interface)

• examples/hello_parl_io.rs - Displays "Hello, World!".
• examples/parl_io.rs - Shows a color gradient and stats.

ESP32 (I2S Parallel Interface)

• examples/hello_i2s_parallel.rs - Displays "Hello, World!".
• examples/i2s_parallel.rs - Shows a color gradient and stats.
• examples/i2s_parallel_latch.rs - Shows a color gradient and stats.
• examples/i2s_parallel_dimming.rs - Shows a color gradient and stats.

Crate Features

• esp32: Enable support for the ESP32
• esp32s3: Enable support for the ESP32-S3
• esp32c6: Enable support for the ESP32-C6
• defmt: Enable logging with defmt
• log: Enable logging with the log crate
• invert-blank: Invert the blank signal, required for some controller boards.
• skip-black-pixels: Forwards to the hub75-framebuffer crate, enabling an optimization that skips writing black pixels to the framebuffer.
• iram: Place the driver’s hot-path (render / DMA wait functions) in Instruction RAM (IRAM) to avoid flash-cache stalls (for example during Wi-Fi, PSRAM, or SPI-flash activity) that can cause visible flicker. Enabling this feature consumes roughly 5–10 KiB of IRAM.

License

This project is dual-licensed under either of the following:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

Contributing

We welcome contributions! Please feel free to submit a Pull Request.

By contributing, you agree that your submissions will be licensed under both the Apache-2.0 and MIT licenses.

Support

If you need help, please open an issue on our GitHub repository.