116 lines
3 KiB
Rust
116 lines
3 KiB
Rust
#![no_std]
|
|
#![no_main]
|
|
#![feature(type_alias_impl_trait)]
|
|
|
|
use core::f32::consts::PI;
|
|
|
|
use defmt::{error, info};
|
|
use embassy_executor::Spawner;
|
|
use embassy_nrf::i2s::{self, Channels, Config, MasterClock, MultiBuffering, Sample as _, SampleWidth, I2S};
|
|
use embassy_nrf::{bind_interrupts, peripherals};
|
|
use {defmt_rtt as _, panic_probe as _};
|
|
|
|
type Sample = i16;
|
|
|
|
const NUM_BUFFERS: usize = 2;
|
|
const NUM_SAMPLES: usize = 4;
|
|
|
|
bind_interrupts!(struct Irqs {
|
|
I2S => i2s::InterruptHandler<peripherals::I2S>;
|
|
});
|
|
|
|
#[embassy_executor::main]
|
|
async fn main(_spawner: Spawner) {
|
|
let p = embassy_nrf::init(Default::default());
|
|
|
|
let master_clock: MasterClock = i2s::ExactSampleRate::_50000.into();
|
|
|
|
let sample_rate = master_clock.sample_rate();
|
|
info!("Sample rate: {}", sample_rate);
|
|
|
|
let mut config = Config::default();
|
|
config.sample_width = SampleWidth::_16bit;
|
|
config.channels = Channels::MonoLeft;
|
|
|
|
let buffers_out = MultiBuffering::<Sample, NUM_BUFFERS, NUM_SAMPLES>::new();
|
|
let buffers_in = MultiBuffering::<Sample, NUM_BUFFERS, NUM_SAMPLES>::new();
|
|
let mut full_duplex_stream = I2S::new_master(p.I2S, Irqs, p.P0_25, p.P0_26, p.P0_27, master_clock, config)
|
|
.full_duplex(p.P0_29, p.P0_28, buffers_out, buffers_in);
|
|
|
|
let mut modulator = SineOsc::new();
|
|
modulator.set_frequency(8.0, 1.0 / sample_rate as f32);
|
|
modulator.set_amplitude(1.0);
|
|
|
|
full_duplex_stream.start().await.expect("I2S Start");
|
|
|
|
loop {
|
|
let (buff_out, buff_in) = full_duplex_stream.buffers();
|
|
for i in 0..NUM_SAMPLES {
|
|
let modulation = (Sample::SCALE as f32 * bipolar_to_unipolar(modulator.generate())) as Sample;
|
|
buff_out[i] = buff_in[i] * modulation;
|
|
}
|
|
|
|
if let Err(err) = full_duplex_stream.send_and_receive().await {
|
|
error!("{}", err);
|
|
}
|
|
}
|
|
}
|
|
|
|
struct SineOsc {
|
|
amplitude: f32,
|
|
modulo: f32,
|
|
phase_inc: f32,
|
|
}
|
|
|
|
impl SineOsc {
|
|
const B: f32 = 4.0 / PI;
|
|
const C: f32 = -4.0 / (PI * PI);
|
|
const P: f32 = 0.225;
|
|
|
|
pub fn new() -> Self {
|
|
Self {
|
|
amplitude: 1.0,
|
|
modulo: 0.0,
|
|
phase_inc: 0.0,
|
|
}
|
|
}
|
|
|
|
pub fn set_frequency(&mut self, freq: f32, inv_sample_rate: f32) {
|
|
self.phase_inc = freq * inv_sample_rate;
|
|
}
|
|
|
|
pub fn set_amplitude(&mut self, amplitude: f32) {
|
|
self.amplitude = amplitude;
|
|
}
|
|
|
|
pub fn generate(&mut self) -> f32 {
|
|
let signal = self.parabolic_sin(self.modulo);
|
|
self.modulo += self.phase_inc;
|
|
if self.modulo < 0.0 {
|
|
self.modulo += 1.0;
|
|
} else if self.modulo > 1.0 {
|
|
self.modulo -= 1.0;
|
|
}
|
|
signal * self.amplitude
|
|
}
|
|
|
|
fn parabolic_sin(&mut self, modulo: f32) -> f32 {
|
|
let angle = PI - modulo * 2.0 * PI;
|
|
let y = Self::B * angle + Self::C * angle * abs(angle);
|
|
Self::P * (y * abs(y) - y) + y
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
fn abs(value: f32) -> f32 {
|
|
if value < 0.0 {
|
|
-value
|
|
} else {
|
|
value
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
fn bipolar_to_unipolar(value: f32) -> f32 {
|
|
(value + 1.0) / 2.0
|
|
}
|