117 lines
3.4 KiB
Rust
117 lines
3.4 KiB
Rust
#![no_std]
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#![no_main]
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use defmt::{debug, error, info};
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use embassy_executor::Spawner;
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use embassy_nrf::i2s::{self, Channels, Config, DoubleBuffering, MasterClock, Sample as _, SampleWidth, I2S};
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use embassy_nrf::pwm::{Prescaler, SimplePwm};
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use embassy_nrf::{bind_interrupts, peripherals};
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use {defmt_rtt as _, panic_probe as _};
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type Sample = i16;
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const NUM_SAMPLES: usize = 500;
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bind_interrupts!(struct Irqs {
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I2S => i2s::InterruptHandler<peripherals::I2S>;
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});
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#[embassy_executor::main]
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async fn main(_spawner: Spawner) {
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let p = embassy_nrf::init(Default::default());
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let master_clock: MasterClock = i2s::ExactSampleRate::_50000.into();
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let sample_rate = master_clock.sample_rate();
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info!("Sample rate: {}", sample_rate);
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let mut config = Config::default();
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config.sample_width = SampleWidth::_16bit;
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config.channels = Channels::MonoLeft;
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let buffers = DoubleBuffering::<Sample, NUM_SAMPLES>::new();
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let mut input_stream =
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I2S::new_master(p.I2S, Irqs, p.P0_25, p.P0_26, p.P0_27, master_clock, config).input(p.P0_29, buffers);
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// Configure the PWM to use the pins corresponding to the RGB leds
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let mut pwm = SimplePwm::new_3ch(p.PWM0, p.P0_23, p.P0_22, p.P0_24);
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pwm.set_prescaler(Prescaler::Div1);
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pwm.set_max_duty(255);
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let mut rms_online = RmsOnline::<NUM_SAMPLES>::default();
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input_stream.start().await.expect("I2S Start");
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loop {
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let rms = rms_online.process(input_stream.buffer());
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let rgb = rgb_from_rms(rms);
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debug!("RMS: {}, RGB: {:?}", rms, rgb);
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for i in 0..3 {
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pwm.set_duty(i, rgb[i].into());
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}
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if let Err(err) = input_stream.receive().await {
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error!("{}", err);
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}
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}
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}
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/// RMS from 0.0 until 0.75 will give green with a proportional intensity
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/// RMS from 0.75 until 0.9 will give a blend between orange and red proportionally to the intensity
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/// RMS above 0.9 will give a red with a proportional intensity
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fn rgb_from_rms(rms: f32) -> [u8; 3] {
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if rms < 0.75 {
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let intensity = rms / 0.75;
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[0, (intensity * 165.0) as u8, 0]
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} else if rms < 0.9 {
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let intensity = (rms - 0.75) / 0.15;
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[200, 165 - (165.0 * intensity) as u8, 0]
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} else {
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let intensity = (rms - 0.9) / 0.1;
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[200 + (55.0 * intensity) as u8, 0, 0]
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}
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}
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pub struct RmsOnline<const N: usize> {
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pub squares: [f32; N],
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pub head: usize,
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}
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impl<const N: usize> Default for RmsOnline<N> {
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fn default() -> Self {
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RmsOnline {
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squares: [0.0; N],
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head: 0,
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}
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}
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}
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impl<const N: usize> RmsOnline<N> {
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pub fn reset(&mut self) {
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self.squares = [0.0; N];
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self.head = 0;
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}
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pub fn process(&mut self, buf: &[Sample]) -> f32 {
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buf.iter()
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.for_each(|sample| self.push(*sample as f32 / Sample::SCALE as f32));
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let sum_of_squares = self.squares.iter().fold(0.0, |acc, v| acc + *v);
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Self::approx_sqrt(sum_of_squares / N as f32)
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}
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pub fn push(&mut self, signal: f32) {
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let square = signal * signal;
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self.squares[self.head] = square;
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self.head = (self.head + 1) % N;
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}
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/// Approximated sqrt taken from [micromath]
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///
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/// [micromath]: https://docs.rs/micromath/latest/src/micromath/float/sqrt.rs.html#11-17
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///
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fn approx_sqrt(value: f32) -> f32 {
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f32::from_bits((value.to_bits() + 0x3f80_0000) >> 1)
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}
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}
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