#![no_std] #![no_main] #![feature(type_alias_impl_trait)] use core::fmt::Write; use embassy_executor::Spawner; use embassy_rp::dma::{AnyChannel, Channel}; use embassy_rp::gpio::Pin; use embassy_rp::peripherals::PIO0; use embassy_rp::pio::{ FifoJoin, PioCommon, PioInstance, PioStateMachine, PioStateMachineInstance, ShiftDirection, SmInstanceBase, }; use embassy_rp::pwm::{Config, Pwm}; use embassy_rp::relocate::RelocatedProgram; use embassy_rp::{into_ref, Peripheral, PeripheralRef}; use embassy_time::{Duration, Instant, Timer}; use {defmt_rtt as _, panic_probe as _}; #[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_CH7, p.PIN_15, { let mut c = Config::default(); c.divider = 125.into(); c.top = 100; c.compare_b = 50; c }); let mut hd = HD44780::new( p.PIO0, p.DMA_CH3, p.PIN_0, p.PIN_1, p.PIN_2, p.PIN_3, p.PIN_4, p.PIN_5, p.PIN_6, ) .await; loop { struct Buf([u8; N], usize); impl Write for Buf { 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(Duration::from_secs(1)).await; } } pub struct HD44780<'l> { dma: PeripheralRef<'l, AnyChannel>, sm: PioStateMachineInstance>, buf: [u8; 40], } impl<'l> HD44780<'l> { pub async fn new( pio: PIO0, dma: impl Peripheral

+ 'l, rs: impl Pin, rw: impl Pin, e: impl Pin, db4: impl Pin, db5: impl Pin, db6: impl Pin, db7: impl Pin, ) -> HD44780<'l> { into_ref!(dma); let db7pin = db7.pin(); let (mut common, mut sm0, ..) = pio.split(); // takes command words ( <0:4>) let prg = pio_proc::pio_asm!( r#" .side_set 1 opt loop: out x, 24 delay: jmp x--, delay out pins, 4 side 1 out null, 4 side 0 jmp !osre, loop irq 0 "#, ); let rs = common.make_pio_pin(rs); let rw = common.make_pio_pin(rw); let e = common.make_pio_pin(e); let db4 = common.make_pio_pin(db4); let db5 = common.make_pio_pin(db5); let db6 = common.make_pio_pin(db6); let db7 = common.make_pio_pin(db7); sm0.set_set_pins(&[&rs, &rw]); embassy_rp::pio_instr_util::set_pindir(&mut sm0, 0b11); sm0.set_set_pins(&[&e]); embassy_rp::pio_instr_util::set_pindir(&mut sm0, 0b1); sm0.set_set_pins(&[&db4, &db5, &db6, &db7]); embassy_rp::pio_instr_util::set_pindir(&mut sm0, 0b11111); let relocated = RelocatedProgram::new(&prg.program); common.write_instr(relocated.origin() as usize, relocated.code()); embassy_rp::pio_instr_util::exec_jmp(&mut sm0, relocated.origin()); sm0.set_clkdiv(125 * 256); let pio::Wrap { source, target } = relocated.wrap(); sm0.set_wrap(source, target); sm0.set_side_enable(true); sm0.set_out_pins(&[&db4, &db5, &db6, &db7]); sm0.set_sideset_base_pin(&e); sm0.set_sideset_count(2); sm0.set_out_shift_dir(ShiftDirection::Left); sm0.set_fifo_join(FifoJoin::TxOnly); sm0.set_autopull(true); sm0.set_pull_threshold(32); sm0.set_enable(true); // init to 8 bit thrice sm0.push_tx((50000 << 8) | 0x30); sm0.push_tx((5000 << 8) | 0x30); sm0.push_tx((200 << 8) | 0x30); // init 4 bit sm0.push_tx((200 << 8) | 0x20); // set font and lines sm0.push_tx((50 << 8) | 0x20); sm0.push_tx(0b1100_0000); sm0.wait_irq(0).await; sm0.set_enable(false); // takes command sequences ( , data...) // many side sets are only there to free up a delay bit! let prg = pio_proc::pio_asm!( r#" .origin 7 .side_set 1 .wrap_target pull side 0 out x 1 side 0 ; !rs out y 7 side 0 ; #data - 1 ; rs/rw to e: >= 60ns ; e high time: >= 500ns ; e low time: >= 500ns ; read data valid after e falling: ~5ns ; write data hold after e falling: ~10ns loop: pull side 0 jmp !x data side 0 command: set pins 0b00 side 0 jmp shift side 0 data: set pins 0b01 side 0 shift: out pins 4 side 1 [9] nop side 0 [9] out pins 4 side 1 [9] mov osr null side 0 [7] out pindirs 4 side 0 set pins 0b10 side 0 busy: nop side 1 [9] jmp pin more side 0 [9] mov osr ~osr side 1 [9] nop side 0 [4] out pindirs 4 side 0 jmp y-- loop side 0 .wrap more: nop side 1 [9] jmp busy side 0 [9] "# ); let relocated = RelocatedProgram::new(&prg.program); common.write_instr(relocated.origin() as usize, relocated.code()); embassy_rp::pio_instr_util::exec_jmp(&mut sm0, relocated.origin()); let pio::Wrap { source, target } = relocated.wrap(); sm0.set_clkdiv(8 * 256); // ~64ns/insn sm0.set_side_enable(false); sm0.set_jmp_pin(db7pin); sm0.set_wrap(source, target); sm0.set_set_pins(&[&rs, &rw]); sm0.set_out_pins(&[&db4, &db5, &db6, &db7]); sm0.set_sideset_base_pin(&e); sm0.set_sideset_count(1); sm0.set_out_shift_dir(ShiftDirection::Left); sm0.set_fifo_join(FifoJoin::TxOnly); sm0.set_enable(true); // display on and cursor on and blinking, reset display sm0.dma_push(dma.reborrow(), &[0x81u8, 0x0f, 1]).await; Self { dma: dma.map_into(), sm: sm0, buf: [0x20; 40], } } pub async fn add_line(&mut self, s: &[u8]) { // move cursor to 0:0, prepare 16 characters self.buf[..3].copy_from_slice(&[0x80, 0x80, 15]); // move line 2 up self.buf.copy_within(22..38, 3); // move cursor to 1:0, prepare 16 characters self.buf[19..22].copy_from_slice(&[0x80, 0xc0, 15]); // file line 2 with spaces self.buf[22..38].fill(0x20); // copy input line let len = s.len().min(16); self.buf[22..22 + len].copy_from_slice(&s[0..len]); // set cursor to 1:15 self.buf[38..].copy_from_slice(&[0x80, 0xcf]); self.sm.dma_push(self.dma.reborrow(), &self.buf).await; } }