Merge pull request #3566 from IvanLi-CN/feat/adc-read-async-stm32g4

STM32: Implement Asynchronous ADC Reading for G4

2 files changed, 219 insertions, 10 deletions

diff --git a/embassy-stm32/src/adc/g4.rs b/embassy-stm32/src/adc/g4.rs
index 3e9ba8ae2..872cf3f06 100644
--- a/embassy-stm32/src/adc/g4.rs
+++ b/embassy-stm32/src/adc/g4.rs
@@ -5,8 +5,11 @@ use pac::adc::vals::{Adcaldif, Difsel, Exten};
 #[cfg(stm32g4)]
 use pac::adc::vals::{Adcaldif, Difsel, Exten, Rovsm, Trovs};
 use pac::adccommon::vals::Presc;
+use stm32_metapac::adc::vals::{Adstp, Dmacfg, Dmaen};
 
-use super::{blocking_delay_us, Adc, AdcChannel, Instance, Resolution, SampleTime};
+use super::{blocking_delay_us, Adc, AdcChannel, AnyAdcChannel, Instance, Resolution, RxDma, SampleTime};
+use crate::adc::SealedAdcChannel;
+use crate::dma::Transfer;
 use crate::time::Hertz;
 use crate::{pac, rcc, Peripheral};
 
@@ -191,10 +194,24 @@ impl<'d, T: Instance> Adc<'d, T> {
     }
 
     fn enable(&mut self) {
-        T::regs().isr().write(|w| w.set_adrdy(true));
-        T::regs().cr().modify(|w| w.set_aden(true));
-        while !T::regs().isr().read().adrdy() {}
-        T::regs().isr().write(|w| w.set_adrdy(true));
+        // Make sure bits are off
+        while T::regs().cr().read().addis() {
+            // spin
+        }
+
+        if !T::regs().cr().read().aden() {
+            // Enable ADC
+            T::regs().isr().modify(|reg| {
+                reg.set_adrdy(true);
+            });
+            T::regs().cr().modify(|reg| {
+                reg.set_aden(true);
+            });
+
+            while !T::regs().isr().read().adrdy() {
+                // spin
+            }
+        }
     }
 
     fn configure(&mut self) {
@@ -327,23 +344,146 @@ impl<'d, T: Instance> Adc<'d, T> {
     pub fn blocking_read(&mut self, channel: &mut impl AdcChannel<T>) -> u16 {
         channel.setup();
 
-        self.read_channel(channel.channel())
+        self.read_channel(channel)
+    }
+
+    /// Read one or multiple ADC channels using DMA.
+    ///
+    /// `sequence` iterator and `readings` must have the same length.
+    ///
+    /// Example
+    /// ```rust,ignore
+    /// use embassy_stm32::adc::{Adc, AdcChannel}
+    ///
+    /// let mut adc = Adc::new(p.ADC1);
+    /// let mut adc_pin0 = p.PA0.degrade_adc();
+    /// let mut adc_pin1 = p.PA1.degrade_adc();
+    /// let mut measurements = [0u16; 2];
+    ///
+    /// adc.read_async(
+    ///     p.DMA1_CH2,
+    ///     [
+    ///         (&mut *adc_pin0, SampleTime::CYCLES160_5),
+    ///         (&mut *adc_pin1, SampleTime::CYCLES160_5),
+    ///     ]
+    ///     .into_iter(),
+    ///     &mut measurements,
+    /// )
+    /// .await;
+    /// defmt::info!("measurements: {}", measurements);
+    /// ```
+    pub async fn read(
+        &mut self,
+        rx_dma: &mut impl RxDma<T>,
+        sequence: impl ExactSizeIterator<Item = (&mut AnyAdcChannel<T>, SampleTime)>,
+        readings: &mut [u16],
+    ) {
+        assert!(sequence.len() != 0, "Asynchronous read sequence cannot be empty");
+        assert!(
+            sequence.len() == readings.len(),
+            "Sequence length must be equal to readings length"
+        );
+        assert!(
+            sequence.len() <= 16,
+            "Asynchronous read sequence cannot be more than 16 in length"
+        );
+
+        // Ensure no conversions are ongoing and ADC is enabled.
+        Self::cancel_conversions();
+        self.enable();
+
+        // Set sequence length
+        T::regs().sqr1().modify(|w| {
+            w.set_l(sequence.len() as u8 - 1);
+        });
+
+        // Configure channels and ranks
+        for (_i, (channel, sample_time)) in sequence.enumerate() {
+            Self::configure_channel(channel, sample_time);
+
+            match _i {
+                0..=3 => {
+                    T::regs().sqr1().modify(|w| {
+                        w.set_sq(_i, channel.channel());
+                    });
+                }
+                4..=8 => {
+                    T::regs().sqr2().modify(|w| {
+                        w.set_sq(_i - 4, channel.channel());
+                    });
+                }
+                9..=13 => {
+                    T::regs().sqr3().modify(|w| {
+                        w.set_sq(_i - 9, channel.channel());
+                    });
+                }
+                14..=15 => {
+                    T::regs().sqr4().modify(|w| {
+                        w.set_sq(_i - 14, channel.channel());
+                    });
+                }
+                _ => unreachable!(),
+            }
+        }
+
+        // Set continuous mode with oneshot dma.
+        // Clear overrun flag before starting transfer.
+        T::regs().isr().modify(|reg| {
+            reg.set_ovr(true);
+        });
+
+        T::regs().cfgr().modify(|reg| {
+            reg.set_discen(false);
+            reg.set_cont(true);
+            reg.set_dmacfg(Dmacfg::ONESHOT);
+            reg.set_dmaen(Dmaen::ENABLE);
+        });
+
+        let request = rx_dma.request();
+        let transfer = unsafe {
+            Transfer::new_read(
+                rx_dma,
+                request,
+                T::regs().dr().as_ptr() as *mut u16,
+                readings,
+                Default::default(),
+            )
+        };
+
+        // Start conversion
+        T::regs().cr().modify(|reg| {
+            reg.set_adstart(true);
+        });
+
+        // Wait for conversion sequence to finish.
+        transfer.await;
+
+        // Ensure conversions are finished.
+        Self::cancel_conversions();
+
+        // Reset configuration.
+        T::regs().cfgr().modify(|reg| {
+            reg.set_cont(false);
+        });
     }
 
-    fn read_channel(&mut self, channel: u8) -> u16 {
+    fn configure_channel(channel: &mut impl AdcChannel<T>, sample_time: SampleTime) {
         // Configure channel
-        Self::set_channel_sample_time(channel, self.sample_time);
+        Self::set_channel_sample_time(channel.channel(), sample_time);
+    }
 
+    fn read_channel(&mut self, channel: &mut impl AdcChannel<T>) -> u16 {
+        Self::configure_channel(channel, self.sample_time);
         #[cfg(stm32h7)]
         {
             T::regs().cfgr2().modify(|w| w.set_lshift(0));
             T::regs()
                 .pcsel()
-                .write(|w| w.set_pcsel(channel as _, Pcsel::PRESELECTED));
+                .write(|w| w.set_pcsel(channel.channel() as _, Pcsel::PRESELECTED));
         }
 
         T::regs().sqr1().write(|reg| {
-            reg.set_sq(0, channel);
+            reg.set_sq(0, channel.channel());
             reg.set_l(0);
         });
 
@@ -358,4 +498,13 @@ impl<'d, T: Instance> Adc<'d, T> {
             T::regs().smpr2().modify(|reg| reg.set_smp((ch - 10) as _, sample_time));
         }
     }
+
+    fn cancel_conversions() {
+        if T::regs().cr().read().adstart() && !T::regs().cr().read().addis() {
+            T::regs().cr().modify(|reg| {
+                reg.set_adstp(Adstp::STOP);
+            });
+            while T::regs().cr().read().adstart() {}
+        }
+    }
 }
diff --git a/examples/stm32g4/src/bin/adc_dma.rs b/examples/stm32g4/src/bin/adc_dma.rs
new file mode 100644
index 000000000..970623b32
--- /dev/null
+++ b/examples/stm32g4/src/bin/adc_dma.rs
@@ -0,0 +1,60 @@
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::adc::{Adc, AdcChannel as _, SampleTime};
+use embassy_stm32::Config;
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+
+static mut DMA_BUF: [u16; 2] = [0; 2];
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let mut read_buffer = unsafe { &mut DMA_BUF[..] };
+
+    let mut config = Config::default();
+    {
+        use embassy_stm32::rcc::*;
+        config.rcc.pll = Some(Pll {
+            source: PllSource::HSI,
+            prediv: PllPreDiv::DIV4,
+            mul: PllMul::MUL85,
+            divp: None,
+            divq: None,
+            // Main system clock at 170 MHz
+            divr: Some(PllRDiv::DIV2),
+        });
+        config.rcc.mux.adc12sel = mux::Adcsel::SYS;
+        config.rcc.sys = Sysclk::PLL1_R;
+    }
+    let p = embassy_stm32::init(config);
+
+    info!("Hello World!");
+
+    let mut adc = Adc::new(p.ADC1);
+
+    let mut dma = p.DMA1_CH1;
+    let mut vrefint_channel = adc.enable_vrefint().degrade_adc();
+    let mut pa0 = p.PA0.degrade_adc();
+
+    loop {
+        adc.read(
+            &mut dma,
+            [
+                (&mut vrefint_channel, SampleTime::CYCLES247_5),
+                (&mut pa0, SampleTime::CYCLES247_5),
+            ]
+            .into_iter(),
+            &mut read_buffer,
+        )
+        .await;
+
+        let vrefint = read_buffer[0];
+        let measured = read_buffer[1];
+        info!("vrefint: {}", vrefint);
+        info!("measured: {}", measured);
+        Timer::after_millis(500).await;
+    }
+}