DAC driver and example

Author: Mirabellensaft

examples/dac_sine.rs

@@ -0,0 +1,78 @@
+#![no_std]
+#![no_main]
+
+//! Example usage for DAC on STM32F303
+// Based on example in stm32hal by David-OConnor
+
+use panic_semihosting as _;
+
+use cortex_m_rt::entry;
+
+use stm32f3xx_hal::{
+    dac::{Dac, DacChannel},
+    pac,
+    prelude::*,
+};
+
+const LUT_LEN: usize = 256;
+
+// A lookup table for sin(x), over one period, using values from 0 - 4095; ie the full range of
+// the STM32 12-bit onboard DAC. Compared to computation, this is faster, at the expense of memory use.
+pub static SIN_X: [u16; crate::LUT_LEN] = [
+    2048, 2098, 2148, 2198, 2248, 2298, 2348, 2398, 2447, 2496, 2545, 2594, 2642, 2690, 2737, 2784,
+    2831, 2877, 2923, 2968, 3013, 3057, 3100, 3143, 3185, 3226, 3267, 3307, 3346, 3385, 3423, 3459,
+    3495, 3530, 3565, 3598, 3630, 3662, 3692, 3722, 3750, 3777, 3804, 3829, 3853, 3876, 3898, 3919,
+    3939, 3958, 3975, 3992, 4007, 4021, 4034, 4045, 4056, 4065, 4073, 4080, 4085, 4089, 4093, 4094,
+    4095, 4094, 4093, 4089, 4085, 4080, 4073, 4065, 4056, 4045, 4034, 4021, 4007, 3992, 3975, 3958,
+    3939, 3919, 3898, 3876, 3853, 3829, 3804, 3777, 3750, 3722, 3692, 3662, 3630, 3598, 3565, 3530,
+    3495, 3459, 3423, 3385, 3346, 3307, 3267, 3226, 3185, 3143, 3100, 3057, 3013, 2968, 2923, 2877,
+    2831, 2784, 2737, 2690, 2642, 2594, 2545, 2496, 2447, 2398, 2348, 2298, 2248, 2198, 2148, 2098,
+    2048, 1997, 1947, 1897, 1847, 1797, 1747, 1697, 1648, 1599, 1550, 1501, 1453, 1405, 1358, 1311,
+    1264, 1218, 1172, 1127, 1082, 1038, 995, 952, 910, 869, 828, 788, 749, 710, 672, 636, 600, 565,
+    530, 497, 465, 433, 403, 373, 345, 318, 291, 266, 242, 219, 197, 176, 156, 137, 120, 103, 88,
+    74, 61, 50, 39, 30, 22, 15, 10, 6, 2, 1, 0, 1, 2, 6, 10, 15, 22, 30, 39, 50, 61, 74, 88, 103,
+    120, 137, 156, 176, 197, 219, 242, 266, 291, 318, 345, 373, 403, 433, 465, 497, 530, 565, 600,
+    636, 672, 710, 749, 788, 828, 869, 910, 952, 995, 1038, 1082, 1127, 1172, 1218, 1264, 1311,
+    1358, 1405, 1453, 1501, 1550, 1599, 1648, 1697, 1747, 1797, 1847, 1897, 1947, 1997,
+];
+
+#[entry]
+/// Main Thread
+fn main() -> ! {
+    // Get peripherals, clocks and freeze them
+    let dp = pac::Peripherals::take().unwrap();
+    let mut rcc = dp.RCC.constrain();
+    // let clocks = rcc.cfgr.freeze(&mut dp.FLASH.constrain().acr);
+
+    // Set up pin PA4 as analog pin.
+    let mut gpioa = dp.GPIOA.split(&mut rcc.ahb);
+    let _dac1_out1 = gpioa.pa4.into_analog(&mut gpioa.moder, &mut gpioa.pupdr);
+
+    // set up led for blinking loop
+    let mut gpioe = dp.GPIOE.split(&mut rcc.ahb);
+    let mut ok_led = gpioe
+        .pe15
+        .into_push_pull_output(&mut gpioe.moder, &mut gpioe.otyper);
+
+    // set up dac1, data is twelve bits, alighned right
+    let mut dac1 = Dac::new(dp.DAC1, &mut rcc.apb1);
+    // enable channel one for single channel mode
+    dac1.enable_channel(DacChannel::One);
+
+    let mut led = true;
+
+    loop {
+        // lookup values for sine wave and write in buffer
+        for value in SIN_X {
+            dac1.write_data(value);
+            cortex_m::asm::delay(8_000);
+        }
+        if led {
+            ok_led.set_low().unwrap();
+            led = false;
+        } else {
+            ok_led.set_high().unwrap();
+            led = true;
+        }
+    }
+}

src/dac.rs

@@ -0,0 +1,58 @@
+//Based on stm32hal by David-OConnor
+
+use cortex_m::asm;
+
+use crate::{
+    gpio::{self, Analog},
+    pac::{dac1, DAC1},
+    rcc::{Rcc, Clocks, AHB, APB1},
+};
+
+#[cfg(any(
+    feature = "stm32f303xb",
+    feature = "stm32f303xc",
+    feature = "stm32f303xd",
+    feature = "stm32f303xe",
+))]
+use crate::pac::DMA1::{self};
+
+use crate::pac::{self, rcc, RCC};
+
+pub enum DacChannel {
+    One,
+    Two,
+}
+
+/// Represents a Digital to Analog Converter (DAC) peripheral.
+pub struct Dac {
+    regs: DAC1,
+}
+
+// todo: Calculate the VDDA vref, as you do with onboard ADCs!
+impl Dac {
+    /// Initialize a DAC peripheral, including  enabling and resetting
+
+    pub fn new(regs: DAC1, abp1: &mut APB1) -> Self {
+    
+        abp1.enr().modify(|_, w| w.dac1en().set_bit());
+        abp1.rstr().modify(|_, w| w.dac1rst().set_bit());
+        abp1.rstr().modify(|_, w| w.dac1rst().clear_bit());
+
+        Self { regs }
+    }
+
+    pub fn enable_channel(&mut self, channel: DacChannel) {
+        let cr = &self.regs.cr;
+
+        cr.modify(|_, w| match channel {
+            DacChannel::One => w.en1().set_bit(),
+            DacChannel::Two => w.en2().set_bit(),
+        });
+    }
+
+    /// the data parameter MUST be a 12-bit value -- values outside that range will result in misbehavior
+    pub fn write_data(&mut self, data: u16) {
+        
+        self.regs.dhr12r1.write(|w| w.dacc1dhr().bits(data))
+    }
+}

src/lib.rs

@@ -187,6 +187,7 @@ pub mod adc;
 #[cfg(all(feature = "can", not(feature = "svd-f301")))]
 #[cfg_attr(docsrs, doc(cfg(feature = "can")))]
 pub mod can;
+pub mod dac;
 pub mod delay;
 pub mod dma;
 pub mod flash;