rp-hal-boards/rp2040-hal/examples/lcd_display.rs

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//! # LCD Display Example
//!
//! In this example, the RP2040 is configured to drive a small two-line
//! alphanumeric LCD using the
//! [HD44780](https://crates.io/crates/hd44780-driver) driver.
//!
//! It drives the LCD by pushing data out of six GPIO pins. It may need to be
//! adapted to your particular board layout and/or pin assignment.
//!
//! See the `Cargo.toml` file for Copyright and licence details.
#![no_std]
#![no_main]
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// The macro for our start-up function
use cortex_m_rt::entry;
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// Ensure we halt the program on panic (if we don't mention this crate it won't
// be linked)
use panic_halt as _;
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// Alias for our HAL crate
use rp2040_hal as hal;
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// Our LCD driver
use hd44780_driver as hd44780;
// Traits we need
use embedded_time::fixed_point::FixedPoint;
use rp2040_hal::clocks::Clock;
// A shorter alias for the Peripheral Access Crate, which provides low-level
// register access
use hal::pac;
/// The linker will place this boot block at the start of our program image. We
/// need this to help the ROM bootloader get our code up and running.
#[link_section = ".boot2"]
#[used]
pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER;
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/// External high-speed crystal on the Raspberry Pi Pico board is 12 MHz. Adjust
/// if your board has a different frequency
const XTAL_FREQ_HZ: u32 = 12_000_000u32;
/// Entry point to our bare-metal application.
///
/// The `#[entry]` macro ensures the Cortex-M start-up code calls this function
/// as soon as all global variables are initialised.
///
/// The function configures the RP2040 peripherals, writes to the LCD, then goes
/// to sleep.
#[entry]
fn main() -> ! {
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// Grab our singleton objects
let mut pac = pac::Peripherals::take().unwrap();
let core = pac::CorePeripherals::take().unwrap();
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// Set up the watchdog driver - needed by the clock setup code
let mut watchdog = hal::watchdog::Watchdog::new(pac.WATCHDOG);
// Configure the clocks
let clocks = hal::clocks::init_clocks_and_plls(
XTAL_FREQ_HZ,
pac.XOSC,
pac.CLOCKS,
pac.PLL_SYS,
pac.PLL_USB,
&mut pac.RESETS,
&mut watchdog,
)
.ok()
.unwrap();
// The delay object lets us wait for specified amounts of time (in
// milliseconds)
let mut delay = cortex_m::delay::Delay::new(core.SYST, clocks.system_clock.freq().integer());
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// The single-cycle I/O block controls our GPIO pins
let sio = hal::sio::Sio::new(pac.SIO);
// Set the pins to their default state
let pins = hal::gpio::Pins::new(
pac.IO_BANK0,
pac.PADS_BANK0,
sio.gpio_bank0,
&mut pac.RESETS,
);
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// Create the LCD driver from some GPIO pins
let mut lcd = hd44780::HD44780::new_4bit(
pins.gpio16.into_push_pull_output(), // Register Select
pins.gpio17.into_push_pull_output(), // Enable
pins.gpio18.into_push_pull_output(), // d4
pins.gpio19.into_push_pull_output(), // d5
pins.gpio20.into_push_pull_output(), // d6
pins.gpio21.into_push_pull_output(), // d7
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&mut delay,
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)
.unwrap();
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// Clear the screen
lcd.reset(&mut delay).unwrap();
lcd.clear(&mut delay).unwrap();
// Write to the top line
lcd.write_str("rp-hal on", &mut delay).unwrap();
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// Move the cursor
lcd.set_cursor_pos(40, &mut delay).unwrap();
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// Write more more text
lcd.write_str("HD44780!", &mut delay).unwrap();
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// Do nothing - we're finished
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#[allow(clippy::empty_loop)]
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loop {
// Empty loop
}
}