embassy/tests/stm32/src/bin/dac.rs

#![no_std]
#![no_main]

// required-features: dac

#[path = "../common.rs"]
mod common;
use core::f32::consts::PI;

use common::*;
use defmt::assert;
use embassy_executor::Spawner;
use embassy_stm32::adc::Adc;
use embassy_stm32::dac::{DacCh1, Value};
use embassy_stm32::dma::NoDma;
use embassy_time::Timer;
use micromath::F32Ext;
use {defmt_rtt as _, panic_probe as _};

#[embassy_executor::main]
async fn main(_spawner: Spawner) {
    // Initialize the board and obtain a Peripherals instance
    let p: embassy_stm32::Peripherals = embassy_stm32::init(config());

    let adc = peri!(p, ADC);
    let dac = peri!(p, DAC);
    let dac_pin = peri!(p, DAC_PIN);
    let mut adc_pin = unsafe { core::ptr::read(&dac_pin) };

    let mut dac = DacCh1::new(dac, NoDma, dac_pin);
    let mut adc = Adc::new(adc);

    #[cfg(feature = "stm32h755zi")]
    let normalization_factor = 256;
    #[cfg(any(feature = "stm32f429zi", feature = "stm32f446re", feature = "stm32g071rb"))]
    let normalization_factor: i32 = 16;

    dac.set(Value::Bit8(0));
    // Now wait a little to obtain a stable value
    Timer::after_millis(30).await;
    let offset = adc.read(&mut adc_pin);

    for v in 0..=255 {
        // First set the DAC output value
        let dac_output_val = to_sine_wave(v);
        dac.set(Value::Bit8(dac_output_val));

        // Now wait a little to obtain a stable value
        Timer::after_millis(30).await;

        // Need to steal the peripherals here because PA4 is obviously in use already
        let measured = adc.read(&mut unsafe { embassy_stm32::Peripherals::steal() }.PA4);
        // Calibrate and normalize the measurement to get close to the dac_output_val
        let measured_normalized = ((measured as i32 - offset as i32) / normalization_factor) as i16;

        //info!("value / measured: {} / {}", dac_output_val, measured_normalized);

        // The deviations are quite enormous but that does not matter since this is only a quick test
        assert!((dac_output_val as i16 - measured_normalized).abs() < 15);
    }

    info!("Test OK");
    cortex_m::asm::bkpt();
}

fn to_sine_wave(v: u8) -> u8 {
    if v >= 128 {
        // top half
        let r = PI * ((v - 128) as f32 / 128.0);
        (r.sin() * 128.0 + 127.0) as u8
    } else {
        // bottom half
        let r = PI + PI * (v as f32 / 128.0);
        (r.sin() * 128.0 + 127.0) as u8
    }
}