Pin fix, improve fifo handling

examples/rp/src/bin/pio_ws2812.rs

@@ -0,0 +1,132 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+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> {
+    sm: StateMachine<'d, P, S>,
+}
+
+impl<'d, P: Instance, const S: usize> Ws2812<'d, P, S> {
+    pub fn new(mut pio: Common<'d, P>, mut sm: StateMachine<'d, P, S>, pin: impl PioPin) -> Self {
+        // Setup sm0
+
+        // prepare the PIO program
+        let side_set = pio::SideSet::new(false, 1, false);
+        let mut a: pio::Assembler<32> = pio::Assembler::new_with_side_set(side_set);
+
+        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;
+
+        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 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]);
+
+        let relocated = RelocatedProgram::new(&prg);
+        cfg.use_program(&pio.load_program(&relocated), &[&out_pin]);
+
+        // Clock config, measured in kHz to avoid overflows
+        // TODO CLOCK_FREQ should come from embassy_rp
+        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
+        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 }
+    }
+
+    pub async fn write(&mut self, colors: &[RGB8]) {
+        for color in colors {
+            let word = (u32::from(color.g) << 24) | (u32::from(color.r) << 16) | (u32::from(color.b) << 8);
+            if !self.sm.tx().try_push(word) {
+                self.sm.tx().wait_push(word).await;
+            }
+        }
+    }
+}
+
+/// Input a value 0 to 255 to get a color value
+/// The colours are a transition r - g - b - back to r.
+fn wheel(mut wheel_pos: u8) -> RGB8 {
+    wheel_pos = 255 - wheel_pos;
+    if wheel_pos < 85 {
+        return (255 - wheel_pos * 3, 0, wheel_pos * 3).into();
+    }
+    if wheel_pos < 170 {
+        wheel_pos -= 85;
+        return (0, wheel_pos * 3, 255 - wheel_pos * 3).into();
+    }
+    wheel_pos -= 170;
+    (wheel_pos * 3, 255 - wheel_pos * 3, 0).into()
+}
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    info!("Start");
+    let p = embassy_rp::init(Default::default());
+
+    let Pio { common, sm0, .. } = Pio::new(p.PIO0);
+
+    // This is the number of leds in the string. Helpfully, the sparkfun thing plus and adafruit
+    // feather boards for the 2040 both have one built in.
+    const NUM_LEDS: usize = 1;
+    let mut data = [RGB8::default(); NUM_LEDS];
+
+    // For the thing plus, use pin 8
+    // For the feather, use pin 16
+    let mut ws2812 = Ws2812::new(common, sm0, p.PIN_8);
+
+    // Loop forever making RGB values and pushing them out to the WS2812.
+    loop {
+        for j in 0..(256 * 5) {
+            debug!("New Colors:");
+            for i in 0..NUM_LEDS {
+                data[i] = wheel((((i * 256) as u16 / NUM_LEDS as u16 + j as u16) & 255) as u8);
+                debug!("R: {} G: {} B: {}", data[i].r, data[i].g, data[i].b);
+            }
+            ws2812.write(&data).await;
+
+            Timer::after(Duration::from_micros(5)).await;
+        }
+    }
+}