embassy/examples/stm32h7/src/bin/dac_dma.rs

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#![no_std]
#![no_main]
#![feature(type_alias_impl_trait)]
use defmt::*;
use embassy_executor::Spawner;
use embassy_stm32::dac::{DacChannel, ValueArray};
use embassy_stm32::pac::timer::vals::{Mms, Opm};
use embassy_stm32::peripherals::{TIM6, TIM7};
use embassy_stm32::rcc::low_level::RccPeripheral;
use embassy_stm32::time::{mhz, Hertz};
use embassy_stm32::timer::low_level::Basic16bitInstance;
use micromath::F32Ext;
use {defmt_rtt as _, panic_probe as _};
pub type Dac1Type =
embassy_stm32::dac::DacCh1<'static, embassy_stm32::peripherals::DAC1, embassy_stm32::peripherals::DMA1_CH3>;
pub type Dac2Type =
embassy_stm32::dac::DacCh2<'static, embassy_stm32::peripherals::DAC1, embassy_stm32::peripherals::DMA1_CH4>;
#[embassy_executor::main]
async fn main(spawner: Spawner) {
let mut config = embassy_stm32::Config::default();
config.rcc.sys_ck = Some(mhz(400));
config.rcc.hclk = Some(mhz(100));
config.rcc.pll1.q_ck = Some(mhz(100));
// Initialize the board and obtain a Peripherals instance
let p: embassy_stm32::Peripherals = embassy_stm32::init(config);
// Obtain two independent channels (p.DAC1 can only be consumed once, though!)
let (dac_ch1, dac_ch2) = embassy_stm32::dac::Dac::new(p.DAC1, p.DMA1_CH3, p.DMA1_CH4, p.PA4, p.PA5).split();
spawner.spawn(dac_task1(dac_ch1)).ok();
spawner.spawn(dac_task2(dac_ch2)).ok();
}
#[embassy_executor::task]
async fn dac_task1(mut dac: Dac1Type) {
let data: &[u8; 256] = &calculate_array::<256>();
info!("TIM6 frequency is {}", TIM6::frequency());
const FREQUENCY: Hertz = Hertz::hz(200);
// Compute the reload value such that we obtain the FREQUENCY for the sine
let reload: u32 = (TIM6::frequency().0 / FREQUENCY.0) / data.len() as u32;
// Depends on your clock and on the specific chip used, you may need higher or lower values here
if reload < 10 {
error!("Reload value {} below threshold!", reload);
}
dac.select_trigger(embassy_stm32::dac::Ch1Trigger::Tim6).unwrap();
dac.enable_channel().unwrap();
TIM6::enable();
TIM6::regs().arr().modify(|w| w.set_arr(reload as u16 - 1));
TIM6::regs().cr2().modify(|w| w.set_mms(Mms::UPDATE));
TIM6::regs().cr1().modify(|w| {
w.set_opm(Opm::DISABLED);
w.set_cen(true);
});
debug!(
"TIM6 Frequency {}, Target Frequency {}, Reload {}, Reload as u16 {}, Samples {}",
TIM6::frequency(),
FREQUENCY,
reload,
reload as u16,
data.len()
);
// Loop technically not necessary if DMA circular mode is enabled
loop {
info!("Loop DAC1");
if let Err(e) = dac.write(ValueArray::Bit8(data), true).await {
error!("Could not write to dac: {}", e);
}
}
}
#[embassy_executor::task]
async fn dac_task2(mut dac: Dac2Type) {
let data: &[u8; 256] = &calculate_array::<256>();
info!("TIM7 frequency is {}", TIM7::frequency());
const FREQUENCY: Hertz = Hertz::hz(600);
let reload: u32 = (TIM7::frequency().0 / FREQUENCY.0) / data.len() as u32;
if reload < 10 {
error!("Reload value {} below threshold!", reload);
}
TIM7::enable();
TIM7::regs().arr().modify(|w| w.set_arr(reload as u16 - 1));
TIM7::regs().cr2().modify(|w| w.set_mms(Mms::UPDATE));
TIM7::regs().cr1().modify(|w| {
w.set_opm(Opm::DISABLED);
w.set_cen(true);
});
dac.select_trigger(embassy_stm32::dac::Ch2Trigger::Tim7).unwrap();
debug!(
"TIM7 Frequency {}, Target Frequency {}, Reload {}, Reload as u16 {}, Samples {}",
TIM7::frequency(),
FREQUENCY,
reload,
reload as u16,
data.len()
);
if let Err(e) = dac.write(ValueArray::Bit8(data), true).await {
error!("Could not write to dac: {}", e);
}
}
fn to_sine_wave(v: u8) -> u8 {
if v >= 128 {
// top half
let r = 3.14 * ((v - 128) as f32 / 128.0);
(r.sin() * 128.0 + 127.0) as u8
} else {
// bottom half
let r = 3.14 + 3.14 * (v as f32 / 128.0);
(r.sin() * 128.0 + 127.0) as u8
}
}
fn calculate_array<const N: usize>() -> [u8; N] {
let mut res = [0; N];
let mut i = 0;
while i < N {
res[i] = to_sine_wave(i as u8);
i += 1;
}
res
}