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//! This example shows powerful PIO module in the RP2040 chip to communicate with a HD44780 display.
//! See (https://www.sparkfun.com/datasheets/LCD/HD44780.pdf)
#![no_std]
#![no_main]
use core::fmt::Write;
use embassy_executor::Spawner;
use embassy_rp::bind_interrupts;
use embassy_rp::peripherals::PIO0;
use embassy_rp::pio::{InterruptHandler, Pio};
use embassy_rp::pio_programs::hd44780::{PioHD44780, PioHD44780CommandSequenceProgram, PioHD44780CommandWordProgram};
use embassy_rp::pwm::{self, Pwm};
use embassy_time::{Instant, Timer};
use {defmt_rtt as _, panic_probe as _};
bind_interrupts!(pub struct Irqs {
PIO0_IRQ_0 => InterruptHandler<PIO0>;
});
#[embassy_executor::main]
async fn main(_spawner: Spawner) {
// this test assumes a 2x16 HD44780 display attached as follow:
// rs = PIN0
// rw = PIN1
// e = PIN2
// db4 = PIN3
// db5 = PIN4
// db6 = PIN5
// db7 = PIN6
// additionally a pwm signal for a bias voltage charge pump is provided on pin 15,
// allowing direct connection of the display to the RP2040 without level shifters.
let p = embassy_rp::init(Default::default());
let _pwm = Pwm::new_output_b(p.PWM_SLICE7, p.PIN_15, {
let mut c = pwm::Config::default();
c.divider = 125.into();
c.top = 100;
c.compare_b = 50;
c
});
let Pio {
mut common, sm0, irq0, ..
} = Pio::new(p.PIO0, Irqs);
let word_prg = PioHD44780CommandWordProgram::new(&mut common);
let seq_prg = PioHD44780CommandSequenceProgram::new(&mut common);
let mut hd = PioHD44780::new(
&mut common,
sm0,
irq0,
p.DMA_CH3,
p.PIN_0,
p.PIN_1,
p.PIN_2,
p.PIN_3,
p.PIN_4,
p.PIN_5,
p.PIN_6,
&word_prg,
&seq_prg,
)
.await;
loop {
struct Buf<const N: usize>([u8; N], usize);
impl<const N: usize> Write for Buf<N> {
fn write_str(&mut self, s: &str) -> Result<(), core::fmt::Error> {
for b in s.as_bytes() {
if self.1 >= N {
return Err(core::fmt::Error);
}
self.0[self.1] = *b;
self.1 += 1;
}
Ok(())
}
}
let mut buf = Buf([0; 16], 0);
write!(buf, "up {}s", Instant::now().as_micros() as f32 / 1e6).unwrap();
hd.add_line(&buf.0[0..buf.1]).await;
Timer::after_secs(1).await;
}
}
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