“Hello, Rust!” in LCD Display

In this program, we will just print “Hello, Rust!” text in the LCD display.

HD44780 Drivers

During my research, I came across many Rust crates for controll the LCD Display, but these two stood out as working well. In this program, we will start by using the hd44780-driver crate.

• hd44780-driver
• liquid_crystal

Project from template

To set up the project, run:

cargo generate --git https://github.com/ImplFerris/pico2-template.git --tag v0.1.0

When prompted, give your project a name, like “lcd-hello” and select RP-HAL as the HAL.

Then, navigate into the project folder:

cd PROJECT_NAME
# For example, if you named your project "lcd-hello":
# cd lcd-hello

Additional Crates required

Update your Cargo.toml to add these additional crate along with the existing dependencies.

#![allow(unused)]
fn main() {
hd44780-driver = "0.4.0"
}

Additional imports

#![allow(unused)]
fn main() {
use hd44780_driver::HD44780;
}

Mapping Pico and LCD Pins

We connect GPIO16 to the RS pin, GPIO17 to the Enable (E) pin, and GPIO18-21 to the D4-D7 data pins of the LCD. We’re using only 4 data pins since we will be working on 4-bit mode.

#![allow(unused)]
fn main() {
// Read Select Pin
let rs = pins.gpio16.into_push_pull_output();

// Enable Pin
let en = pins.gpio17.into_push_pull_output();

// Data Pins
let d4 = pins.gpio18.into_push_pull_output();
let d5 = pins.gpio19.into_push_pull_output();
let d6 = pins.gpio20.into_push_pull_output();
let d7 = pins.gpio21.into_push_pull_output();

}

Write Text to the LCD

Here, we initialize the LCD module, clear the screen, and then write the text “Hello, Rust!”.

#![allow(unused)]
fn main() {
// LCD Init
let mut lcd = HD44780::new_4bit(rs, en, d4, d5, d6, d7, &mut timer).unwrap();

// Clear the screen
lcd.reset(&mut timer).unwrap();
lcd.clear(&mut timer).unwrap();

// Write to the top line
lcd.write_str("Hello, Rust!", &mut timer).unwrap();
}

Clone the existing project

You can clone (or refer) project I created and navigate to the lcd-hello folder.

git clone https://github.com/ImplFerris/pico2-rp-projects
cd pico2-projects/lcd-hello/