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//! [ws2812](https://www.sparkfun.com/datasheets/LCD/HD44780.pdf)
use embassy_time::Timer;
use fixed::types::U24F8;
use smart_leds::RGB8;
use crate::clocks::clk_sys_freq;
use crate::dma::{AnyChannel, Channel};
use crate::pio::{
Common, Config, FifoJoin, Instance, LoadedProgram, PioPin, ShiftConfig, ShiftDirection, StateMachine,
};
use crate::Peri;
const T1: u8 = 2; // start bit
const T2: u8 = 5; // data bit
const T3: u8 = 3; // stop bit
const CYCLES_PER_BIT: u32 = (T1 + T2 + T3) as u32;
/// This struct represents a ws2812 program loaded into pio instruction memory.
pub struct PioWs2812Program<'a, PIO: Instance> {
prg: LoadedProgram<'a, PIO>,
}
impl<'a, PIO: Instance> PioWs2812Program<'a, PIO> {
/// Load the ws2812 program into the given pio
pub fn new(common: &mut Common<'a, PIO>) -> Self {
let side_set = pio::SideSet::new(false, 1, false);
let mut a: pio::Assembler<32> = pio::Assembler::new_with_side_set(side_set);
let mut wrap_target = a.label();
let mut wrap_source = a.label();
let mut do_zero = a.label();
a.set_with_side_set(pio::SetDestination::PINDIRS, 1, 0);
a.bind(&mut wrap_target);
// Do stop bit
a.out_with_delay_and_side_set(pio::OutDestination::X, 1, T3 - 1, 0);
// Do start bit
a.jmp_with_delay_and_side_set(pio::JmpCondition::XIsZero, &mut do_zero, T1 - 1, 1);
// Do data bit = 1
a.jmp_with_delay_and_side_set(pio::JmpCondition::Always, &mut wrap_target, T2 - 1, 1);
a.bind(&mut do_zero);
// Do data bit = 0
a.nop_with_delay_and_side_set(T2 - 1, 0);
a.bind(&mut wrap_source);
let prg = a.assemble_with_wrap(wrap_source, wrap_target);
let prg = common.load_program(&prg);
Self { prg }
}
}
/// Pio backed ws2812 driver
/// Const N is the number of ws2812 leds attached to this pin
pub struct PioWs2812<'d, P: Instance, const S: usize, const N: usize> {
dma: Peri<'d, AnyChannel>,
sm: StateMachine<'d, P, S>,
}
impl<'d, P: Instance, const S: usize, const N: usize> PioWs2812<'d, P, S, N> {
/// Configure a pio state machine to use the loaded ws2812 program.
pub fn new(
pio: &mut Common<'d, P>,
mut sm: StateMachine<'d, P, S>,
dma: Peri<'d, impl Channel>,
pin: Peri<'d, impl PioPin>,
program: &PioWs2812Program<'d, P>,
) -> Self {
// Setup sm0
let mut cfg = Config::default();
// Pin config
let out_pin = pio.make_pio_pin(pin);
cfg.set_out_pins(&[&out_pin]);
cfg.set_set_pins(&[&out_pin]);
cfg.use_program(&program.prg, &[&out_pin]);
// Clock config, measured in kHz to avoid overflows
let clock_freq = U24F8::from_num(clk_sys_freq() / 1000);
let ws2812_freq = U24F8::from_num(800);
let bit_freq = ws2812_freq * CYCLES_PER_BIT;
cfg.clock_divider = clock_freq / bit_freq;
// FIFO config
cfg.fifo_join = FifoJoin::TxOnly;
cfg.shift_out = ShiftConfig {
auto_fill: true,
threshold: 24,
direction: ShiftDirection::Left,
};
sm.set_config(&cfg);
sm.set_enable(true);
Self { dma: dma.into(), sm }
}
/// Write a buffer of [smart_leds::RGB8] to the ws2812 string
pub async fn write(&mut self, colors: &[RGB8; N]) {
// Precompute the word bytes from the colors
let mut words = [0u32; N];
for i in 0..N {
let word = (u32::from(colors[i].g) << 24) | (u32::from(colors[i].r) << 16) | (u32::from(colors[i].b) << 8);
words[i] = word;
}
// DMA transfer
self.sm.tx().dma_push(self.dma.reborrow(), &words, false).await;
Timer::after_micros(55).await;
}
}
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