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rp/pio: configure state machines with Config struct

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the many individual sets aren't very efficient, and almost no checks
were done to ensure that the configuration written to the hardware was
actually valid. this adresses both of these.
This commit is contained in:
pennae
2023-05-06 11:36:07 +02:00
parent 2873cb93ee
commit 8e4d65e163
6 changed files with 299 additions and 284 deletions
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37
examples/rp/src/bin/ws2812-pio.rs
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@ -3,10 +3,12 @@
#![feature(type_alias_impl_trait)]
use defmt::*;
use embassy_embedded_hal::SetConfig;
use embassy_executor::Spawner;
use embassy_rp::pio::{Common, FifoJoin, Instance, Pio, PioPin, ShiftDirection, StateMachine};
use embassy_rp::pio::{Common, Config, FifoJoin, Instance, Pio, PioPin, ShiftConfig, ShiftDirection, StateMachine};
use embassy_rp::relocate::RelocatedProgram;
use embassy_time::{Duration, Timer};
use fixed_macro::fixed;
use smart_leds::RGB8;
use {defmt_rtt as _, panic_probe as _};
pub struct Ws2812<'d, P: Instance, const S: usize> {
@ -43,35 +45,30 @@ impl<'d, P: Instance, const S: usize> Ws2812<'d, P, S> {
a.bind(&mut wrap_source);
let prg = a.assemble_with_wrap(wrap_source, wrap_target);
let mut cfg = Config::default();
// Pin config
let out_pin = pio.make_pio_pin(pin);
let relocated = RelocatedProgram::new(&prg);
sm.use_program(&pio.load_program(&relocated), &[&out_pin]);
cfg.use_program(&pio.load_program(&relocated), &[&out_pin]);
// Clock config
// Clock config, measured in kHz to avoid overflows
// TODO CLOCK_FREQ should come from embassy_rp
const CLOCK_FREQ: u32 = 125_000_000;
const WS2812_FREQ: u32 = 800_000;
let bit_freq = WS2812_FREQ * CYCLES_PER_BIT;
let mut int = CLOCK_FREQ / bit_freq;
let rem = CLOCK_FREQ - (int * bit_freq);
let frac = (rem * 256) / bit_freq;
// 65536.0 is represented as 0 in the pio's clock divider
if int == 65536 {
int = 0;
}
sm.set_clkdiv((int << 8) | frac);
let clock_freq = fixed!(125_000: U24F8);
let ws2812_freq = fixed!(800: U24F8);
let bit_freq = ws2812_freq * CYCLES_PER_BIT;
cfg.clock_divider = clock_freq / bit_freq;
// FIFO config
sm.set_autopull(true);
sm.set_fifo_join(FifoJoin::TxOnly);
sm.set_pull_threshold(24);
sm.set_out_shift_dir(ShiftDirection::Left);
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 { sm }