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// This example is written for an STM32F411 chip communicating with an external
// PCM5102a DAC. Remap pins, change clock speeds, etc. as necessary for your own
// hardware.
//
// NOTE: This example outputs potentially loud audio. Please run responsibly.
#![no_std]
#![no_main]
use embassy_executor::Spawner;
use embassy_stm32::i2s::{Config, Format, I2S};
use embassy_stm32::time::Hertz;
use {defmt_rtt as _, panic_probe as _};
#[embassy_executor::main]
async fn main(_spawner: Spawner) {
let config = {
use embassy_stm32::rcc::*;
let mut config = embassy_stm32::Config::default();
config.rcc.hse = Some(Hse {
freq: Hertz::mhz(25),
mode: HseMode::Oscillator,
});
config.rcc.pll_src = PllSource::HSE;
config.rcc.pll = Some(Pll {
prediv: PllPreDiv::DIV25,
mul: PllMul::MUL192,
divp: Some(PllPDiv::DIV2),
divq: Some(PllQDiv::DIV4),
divr: None,
});
config.rcc.sys = Sysclk::PLL1_P;
config.rcc.ahb_pre = AHBPrescaler::DIV1;
config.rcc.apb1_pre = APBPrescaler::DIV2;
config.rcc.apb2_pre = APBPrescaler::DIV1;
// reference your chip's manual for proper clock settings; this config
// is recommended for a 32 bit frame at 48 kHz sample rate
config.rcc.plli2s = Some(Pll {
prediv: PllPreDiv::DIV25,
mul: PllMul::MUL384,
divp: None,
divq: None,
divr: Some(PllRDiv::DIV5),
});
config.enable_debug_during_sleep = true;
config
};
let p = embassy_stm32::init(config);
// stereo wavetable generation
let mut wavetable = [0u16; 1200];
for (i, frame) in wavetable.chunks_mut(2).enumerate() {
frame[0] = ((((i / 150) % 2) * 2048) as i16 - 1024) as u16; // 160 Hz square wave in left channel
frame[1] = ((((i / 100) % 2) * 2048) as i16 - 1024) as u16; // 240 Hz square wave in right channel
}
// i2s configuration
let mut dma_buffer = [0u16; 2400];
let mut i2s_config = Config::default();
i2s_config.format = Format::Data16Channel32;
i2s_config.master_clock = false;
let mut i2s = I2S::new_txonly_nomck(
p.SPI3,
p.PB5, // sd
p.PA15, // ws
p.PB3, // ck
p.DMA1_CH7,
&mut dma_buffer,
i2s_config,
);
i2s.start();
loop {
i2s.write(&wavetable).await.ok();
}
}
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