mirror of
https://github.com/italicsjenga/rp-hal-boards.git
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123 lines
3.5 KiB
Rust
123 lines
3.5 KiB
Rust
//! # LCD Display Example
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//!
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//! In this example, the RP2040 is configured to drive a small two-line
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//! alphanumeric LCD using the
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//! [HD44780](https://crates.io/crates/hd44780-driver) driver.
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//!
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//! It drives the LCD by pushing data out of six GPIO pins. It may need to be
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//! adapted to your particular board layout and/or pin assignment.
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//!
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//! See the `Cargo.toml` file for Copyright and licence details.
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#![no_std]
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#![no_main]
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// The macro for our start-up function
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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
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// be linked)
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use panic_halt as _;
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// Alias for our HAL crate
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use rp2040_hal as hal;
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// Our LCD driver
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use hd44780_driver as hd44780;
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// Some traits we need
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use embedded_time::fixed_point::FixedPoint;
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use rp2040_hal::clocks::Clock;
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// A shorter alias for the Peripheral Access Crate, which provides low-level
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// register access
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use hal::pac;
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/// The linker will place this boot block at the start of our program image. We
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/// need this to help the ROM bootloader get our code up and running.
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#[link_section = ".boot2"]
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#[used]
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pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_W25Q080;
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/// External high-speed crystal on the Raspberry Pi Pico board is 12 MHz. Adjust
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/// if your board has a different frequency
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const XTAL_FREQ_HZ: u32 = 12_000_000u32;
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/// Entry point to our bare-metal application.
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///
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/// The `#[entry]` macro ensures the Cortex-M start-up code calls this function
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/// as soon as all global variables are initialised.
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///
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/// The function configures the RP2040 peripherals, writes to the LCD, then goes
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/// to sleep.
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#[entry]
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fn main() -> ! {
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// Grab our singleton objects
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let mut pac = pac::Peripherals::take().unwrap();
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let core = pac::CorePeripherals::take().unwrap();
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// Set up the watchdog driver - needed by the clock setup code
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let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
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// Configure the clocks
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let clocks = hal::clocks::init_clocks_and_plls(
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XTAL_FREQ_HZ,
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pac.XOSC,
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pac.CLOCKS,
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pac.PLL_SYS,
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pac.PLL_USB,
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&mut pac.RESETS,
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&mut watchdog,
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)
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.ok()
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.unwrap();
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// The delay object lets us wait for specified amounts of time (in
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// milliseconds)
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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
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let sio = hal::Sio::new(pac.SIO);
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// Set the pins to their default state
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let pins = hal::gpio::Pins::new(
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pac.IO_BANK0,
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pac.PADS_BANK0,
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sio.gpio_bank0,
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&mut pac.RESETS,
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);
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// Create the LCD driver from some GPIO pins
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let mut lcd = hd44780::HD44780::new_4bit(
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pins.gpio16.into_push_pull_output(), // Register Select
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pins.gpio17.into_push_pull_output(), // Enable
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pins.gpio18.into_push_pull_output(), // d4
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pins.gpio19.into_push_pull_output(), // d5
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pins.gpio20.into_push_pull_output(), // d6
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pins.gpio21.into_push_pull_output(), // d7
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&mut delay,
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)
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.unwrap();
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// Clear the screen
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lcd.reset(&mut delay).unwrap();
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lcd.clear(&mut delay).unwrap();
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// Write to the top line
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lcd.write_str("rp-hal on", &mut delay).unwrap();
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// Move the cursor
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lcd.set_cursor_pos(40, &mut delay).unwrap();
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// Write more more text
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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 {
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// Empty loop
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}
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}
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// End of file
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