Grove LCD RGB Backlight - Rust Driver

A platform-agnostic Rust driver for the Grove LCD RGB Backlight display using embedded-hal traits. Provides full control over the 16x2 character LCD with RGB backlight via I2C.

Features

• ✅ Full LCD control (clear, home, cursor positioning)
• ✅ RGB backlight color control (16.7 million colors)
• ✅ Custom character support (up to 8 custom chars)
• ✅ Display scrolling and text direction control
• ✅ Cursor visibility and blink control
• ✅ Automatic v4/v5 hardware detection
• ✅ Platform-agnostic using embedded-hal 1.0
• ✅ no_std compatible
• ✅ Comprehensive examples for ESP32-C6

Hardware Support

The Grove LCD RGB Backlight uses two I2C devices:

• LCD Controller: Address 0x3E (HD44780-compatible)
• RGB Controller v4: Address 0x62 (PCA9632)
• RGB Controller v5: Address 0x30 (SGM31323)

The driver automatically detects which version you have and uses the appropriate configuration.

Installation

Add this to your Cargo.toml:

[dependencies]
grove-lcd-rgb = { git = "https://github.com/maththedude/grove-lcd-rgb" }
embedded-hal = "1.0"

Or from crates.io (once published):

[dependencies]
grove-lcd-rgb = "0.1"

Quick Start

use grove_lcd_rgb::GroveLcd;

// Create LCD instance with your I2C peripheral and delay provider
let mut lcd = GroveLcd::new(i2c, delay);

// Initialize LCD (16 columns, 2 rows)
lcd.begin(16, 2)?;

// Set backlight color to green
lcd.set_rgb(0, 255, 0)?;

// Display text
lcd.print("Hello, World!")?;

// Set cursor to second line
lcd.set_cursor(0, 1)?;
lcd.print("Grove LCD")?;

ESP32-C6 Example

#![no_std]
#![no_main]

use esp_backtrace as _;
use esp_hal::{delay::Delay, i2c::master::{Config, I2c}};
use grove_lcd_rgb::GroveLcd;

esp_alloc::heap_allocator!(#[esp_hal::ram(reclaimed)] size: 65536);

#[esp_hal::main]
fn main() -> ! {
    let peripherals = esp_hal::init(esp_hal::Config::default());
    
    let i2c = I2c::new(peripherals.I2C0, Config::default())
        .unwrap()
        .with_sda(peripherals.GPIO6)
        .with_scl(peripherals.GPIO7);
    
    let delay = Delay::new();
    let mut lcd = GroveLcd::new(i2c, delay);
    
    lcd.begin(16, 2).unwrap();
    lcd.set_rgb(0, 255, 0).unwrap();
    lcd.print("Hello, ESP32!").unwrap();
    
    loop {}
}

Examples

The crate includes several examples for ESP32-C6. To run them:

# Basic "Hello World" example
cargo run --example esp32c6_basic --release

# I2C device scanner
cargo run --example esp32c6_i2c_scan --release

# Color cycling demo
cargo run --example esp32c6_color_test --release

# Counter with color changes
cargo run --example esp32c6_counter --release

# Full thermostat example
cargo run --example esp32c6_thermostat --release

# Advanced diagnostic tool
cargo run --example esp32c6_diagnostic --release

API Overview

Initialization

lcd.begin(cols: u8, rows: u8) -> Result<(), LcdError<E>>

Display Control

lcd.clear()                               // Clear display
lcd.home()                                // Return cursor to (0,0)
lcd.set_cursor(col: u8, row: u8)         // Position cursor
lcd.display()                             // Turn display on
lcd.no_display()                          // Turn display off

Backlight Control

lcd.set_rgb(r: u8, g: u8, b: u8)         // Set RGB color
lcd.backlight_white()                     // Set to white
lcd.backlight_off()                       // Turn off backlight

Text Operations

lcd.print(s: &str)                        // Print string
lcd.write(value: u8)                      // Write single byte

Cursor Control

lcd.cursor()                              // Show cursor
lcd.no_cursor()                           // Hide cursor
lcd.blink()                               // Blink cursor
lcd.no_blink()                            // Stop blinking

Advanced Features

lcd.scroll_display_left()                // Scroll content left
lcd.scroll_display_right()               // Scroll content right
lcd.create_char(location, charmap)       // Create custom character
lcd.left_to_right()                      // Text flows left to right
lcd.right_to_left()                      // Text flows right to left

Hardware Differences: v4 vs v5

The driver automatically detects and handles both versions!

Wiring for ESP32-C6

Grove LCD          ESP32-C6
---------          --------
GND                GND
VCC                5V (or 3.3V for v5)
SDA                GPIO6 (configurable)
SCL                GPIO7 (configurable)

Troubleshooting

Display not working?

1. Run the I2C scanner example to verify devices are detected
2. Check power supply (3.3V or 5V)
3. Verify SDA/SCL connections
4. Ensure pull-up resistors are present (usually built into Grove modules)

Colors not working on v5?

The driver should auto-detect v5 hardware. If colors don't work:

• Verify the RGB controller is detected at address 0x30
• Check that you're using the latest version of this crate
• Try the diagnostic example for detailed testing

Need help?

• Check the examples directory
• Read the API documentation

Using in Your Project

Add to your Cargo.toml:

[dependencies]
grove-lcd-rgb = { git = "https://github.com/maththedude/grove-lcd-rgb" }
# Or after publishing:
# grove-lcd-rgb = "0.1"

Then in your code:

use grove_lcd_rgb::GroveLcd;

let mut lcd = GroveLcd::new(i2c, delay);
lcd.begin(16, 2)?;
lcd.print("Working!")?;

License

Licensed under either of:

• 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)

at your option.

Credits

Based on the Seeed Studio Grove LCD RGB Backlight Arduino library.

AI Useage

Publicly avalible large-language models were used in the production of this library. The rights of the models' trainers to use the training data they did cannot be verified. If this violates the laws, organizational standards, or moral standards that bind you, please refrain from using any of this code.