2 files changed, 143 insertions, 0 deletions

diff --git a/examples/rp/Cargo.toml b/examples/rp/Cargo.toml
index f07684f29..1e8870ed7 100644
--- a/examples/rp/Cargo.toml
+++ b/examples/rp/Cargo.toml
@@ -28,6 +28,7 @@ embedded-graphics = "0.7.1"
 st7789 = "0.6.1"
 display-interface = "0.4.1"
 byte-slice-cast = { version = "1.2.0", default-features = false }
+smart-leds = "0.3.0"
 
 embedded-hal-1 = { package = "embedded-hal", version = "=1.0.0-alpha.9" }
 embedded-hal-async = "0.2.0-alpha.0"
diff --git a/examples/rp/src/bin/ws2812-pio.rs b/examples/rp/src/bin/ws2812-pio.rs
new file mode 100644
index 000000000..5f8a3baee
--- /dev/null
+++ b/examples/rp/src/bin/ws2812-pio.rs
@@ -0,0 +1,142 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_rp::gpio::{self, Pin};
+use embassy_rp::pio::{
+    FifoJoin, PioInstance, PioPeripheral, PioStateMachine, PioStateMachineInstance, ShiftDirection, SmInstance,
+};
+use embassy_rp::pio_instr_util;
+use embassy_rp::relocate::RelocatedProgram;
+use embassy_time::{Duration, Timer};
+use smart_leds::RGB8;
+use {defmt_rtt as _, panic_probe as _};
+pub struct Ws2812<P: PioInstance, S: SmInstance> {
+    sm: PioStateMachineInstance<P, S>,
+}
+
+impl<P: PioInstance, S: SmInstance> Ws2812<P, S> {
+    pub fn new(mut sm: PioStateMachineInstance<P, S>, pin: gpio::AnyPin) -> 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 relocated = RelocatedProgram::new(&prg);
+        sm.write_instr(relocated.origin() as usize, relocated.code());
+        pio_instr_util::exec_jmp(&mut sm, relocated.origin());
+
+        // Pin config
+        let out_pin = sm.make_pio_pin(pin);
+        sm.set_set_pins(&[&out_pin]);
+        sm.set_sideset_base_pin(&out_pin);
+        sm.set_sideset_count(1);
+
+        // Clock config
+        // 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 pio::Wrap { source, target } = relocated.wrap();
+        sm.set_wrap(source, target);
+
+        // FIFO config
+        sm.set_autopull(true);
+        sm.set_fifo_join(FifoJoin::TxOnly);
+        sm.set_pull_threshold(24);
+        sm.set_out_shift_dir(ShiftDirection::Left);
+
+        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);
+            self.sm.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 (_pio0, sm0, _sm1, _sm2, _sm3) = p.PIO0.split();
+
+    // 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(sm0, p.PIN_8.degrade());
+
+    // 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;
+        }
+    }
+}