mirror of
https://github.com/italicsjenga/rp-hal-boards.git
synced 2024-10-17 22:41:30 +11:00
44019781e2
- Clippy warns about empty loops, https://github.com/rust-lang/rust-clippy/issues/6161 - wfi allows to CPU to save some power WFI was avoided in examples for fear of ill interactions with debuggers. However the rp2040 debug port does continue to work, as long as the relevant clocks are not disabled in SLEEP_EN0/SLEEP_EN1. (By default, all clocks stay enabled in sleep mode.) This patch replaces several different workarounds with just calling wfi.
122 lines
3.5 KiB
Rust
122 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 license 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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loop {
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cortex_m::asm::wfi();
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}
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}
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// End of file
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