adc: move enable after configure_sequence

3 files changed, 70 insertions, 34 deletions

diff --git a/embassy-stm32/src/adc/g4.rs b/embassy-stm32/src/adc/g4.rs
index bd8ccbf17..4957123a1 100644
--- a/embassy-stm32/src/adc/g4.rs
+++ b/embassy-stm32/src/adc/g4.rs
@@ -1,14 +1,12 @@
 #[cfg(stm32g4)]
 use pac::adc::regs::Difsel as DifselReg;
 #[allow(unused)]
+#[cfg(stm32g4)]
+pub use pac::adc::vals::{Adcaldif, Adstp, Difsel, Dmacfg, Dmaen, Exten, Rovsm, Trovs};
+#[allow(unused)]
 #[cfg(stm32h7)]
 use pac::adc::vals::{Adcaldif, Difsel, Exten};
-#[allow(unused)]
-#[cfg(stm32g4)]
-pub use pac::adc::vals::{Adcaldif, Difsel, Exten, Rovsm, Trovs};
-pub use pac::adccommon::vals::Presc;
-pub use stm32_metapac::adc::vals::{Adstp, Dmacfg, Dmaen};
-pub use stm32_metapac::adccommon::vals::Dual;
+pub use pac::adccommon::vals::{Dual, Presc};
 
 use super::{
     Adc, AnyAdcChannel, ConversionMode, Instance, RegularConversionMode, Resolution, RxDma, SampleTime,
@@ -176,6 +174,8 @@ impl<T: Instance> super::SealedAnyInstance for T {
     }
 
     fn configure_sequence(sequence: impl ExactSizeIterator<Item = ((u8, bool), SampleTime)>) {
+        T::regs().cr().modify(|w| w.set_aden(false));
+
         // Set sequence length
         T::regs().sqr1().modify(|w| {
             w.set_l(sequence.len() as u8 - 1);
@@ -183,36 +183,34 @@ impl<T: Instance> super::SealedAnyInstance for T {
 
         #[cfg(stm32g4)]
         let mut difsel = DifselReg::default();
+        let mut smpr = T::regs().smpr().read();
+        let mut smpr2 = T::regs().smpr2().read();
+        let mut sqr1 = T::regs().sqr1().read();
+        let mut sqr2 = T::regs().sqr2().read();
+        let mut sqr3 = T::regs().sqr3().read();
+        let mut sqr4 = T::regs().sqr4().read();
 
         // Configure channels and ranks
         for (_i, ((ch, is_differential), sample_time)) in sequence.enumerate() {
             let sample_time = sample_time.into();
             if ch <= 9 {
-                T::regs().smpr().modify(|reg| reg.set_smp(ch as _, sample_time));
+                smpr.set_smp(ch as _, sample_time);
             } else {
-                T::regs().smpr2().modify(|reg| reg.set_smp((ch - 10) as _, sample_time));
+                smpr2.set_smp((ch - 10) as _, sample_time);
             }
 
             match _i {
                 0..=3 => {
-                    T::regs().sqr1().modify(|w| {
-                        w.set_sq(_i, ch);
-                    });
+                    sqr1.set_sq(_i, ch);
                 }
                 4..=8 => {
-                    T::regs().sqr2().modify(|w| {
-                        w.set_sq(_i - 4, ch);
-                    });
+                    sqr2.set_sq(_i - 4, ch);
                 }
                 9..=13 => {
-                    T::regs().sqr3().modify(|w| {
-                        w.set_sq(_i - 9, ch);
-                    });
+                    sqr3.set_sq(_i - 9, ch);
                 }
                 14..=15 => {
-                    T::regs().sqr4().modify(|w| {
-                        w.set_sq(_i - 14, ch);
-                    });
+                    sqr4.set_sq(_i - 14, ch);
                 }
                 _ => unreachable!(),
             }
@@ -232,12 +230,14 @@ impl<T: Instance> super::SealedAnyInstance for T {
             }
         }
 
+        T::regs().smpr().write_value(smpr);
+        T::regs().smpr2().write_value(smpr2);
+        T::regs().sqr1().write_value(sqr1);
+        T::regs().sqr2().write_value(sqr2);
+        T::regs().sqr3().write_value(sqr3);
+        T::regs().sqr4().write_value(sqr4);
         #[cfg(stm32g4)]
-        {
-            T::regs().cr().modify(|w| w.set_aden(false));
-            T::regs().difsel().write_value(difsel);
-            T::enable();
-        }
+        T::regs().difsel().write_value(difsel);
     }
 }
 
diff --git a/embassy-stm32/src/adc/mod.rs b/embassy-stm32/src/adc/mod.rs
index 13f8a1544..74648cc21 100644
--- a/embassy-stm32/src/adc/mod.rs
+++ b/embassy-stm32/src/adc/mod.rs
@@ -192,10 +192,16 @@ impl<'d, T: AnyInstance> Adc<'d, T> {
         #[cfg(any(adc_v1, adc_c0, adc_l0, adc_v2, adc_g4, adc_v4, adc_u5, adc_wba))]
         channel.setup();
 
-        #[cfg(not(adc_v4))]
+        #[cfg(any(adc_v2, adc_v3, adc_g0, adc_h7rs, adc_u0, adc_u5, adc_wba, adc_c0))]
         T::enable();
         T::configure_sequence([((channel.channel(), channel.is_differential()), sample_time)].into_iter());
 
+        // On chips with differential channels, enable after configure_sequence to allow setting differential channels
+        //
+        // TODO: If hardware allows, enable after configure_sequence on all chips
+        #[cfg(any(adc_g4, adc_h5))]
+        T::enable();
+
         T::convert()
     }
 
@@ -229,10 +235,10 @@ impl<'d, T: AnyInstance> Adc<'d, T> {
     /// Note: This is not very efficient as the ADC needs to be reconfigured for each read. Use
     /// `into_ring_buffered`, `into_ring_buffered_and_injected`
     ///
-    /// In STM32C0, channels bigger than 14 cannot be read using sequencer, so you have to use
-    /// either blocking reads or use the mechanism to read in HW order (CHSELRMOD=0).
-    ///
-    /// In addtion, on STM320, this method will panic if the channels are not passed in order
+    /// Note: Depending on hardware limitations, this method may require channels to be passed
+    /// in order or require the sequence to have the same sample time for all channnels, depending
+    /// on the number and properties of the channels in the sequence. This method will panic if
+    /// the hardware cannot deliver the requested configuration.
     pub async fn read(
         &mut self,
         rx_dma: embassy_hal_internal::Peri<'_, impl RxDma<T>>,
@@ -249,14 +255,20 @@ impl<'d, T: AnyInstance> Adc<'d, T> {
             "Asynchronous read sequence cannot be more than 16 in length"
         );
 
-        // Ensure no conversions are ongoing and ADC is enabled.
+        // Ensure no conversions are ongoing
         T::stop();
+        #[cfg(any(adc_g0, adc_v3, adc_h7rs, adc_u0, adc_v4, adc_u5, adc_wba, adc_c0))]
         T::enable();
 
         T::configure_sequence(
             sequence.map(|(channel, sample_time)| ((channel.channel, channel.is_differential), sample_time)),
         );
 
+        // On chips with differential channels, enable after configure_sequence to allow setting differential channels
+        //
+        // TODO: If hardware allows, enable after configure_sequence on all chips
+        #[cfg(any(adc_g4, adc_h5))]
+        T::enable();
         T::configure_dma(ConversionMode::Singular);
 
         let request = rx_dma.request();
@@ -294,6 +306,11 @@ impl<'d, T: AnyInstance> Adc<'d, T> {
     ///
     /// # Returns
     /// A `RingBufferedAdc<'a, T>` instance configured for continuous DMA-based sampling.
+    ///
+    /// Note: Depending on hardware limitations, this method may require channels to be passed
+    /// in order or require the sequence to have the same sample time for all channnels, depending
+    /// on the number and properties of the channels in the sequence. This method will panic if
+    /// the hardware cannot deliver the requested configuration.
     pub fn into_ring_buffered<'a>(
         self,
         dma: embassy_hal_internal::Peri<'a, impl RxDma<T>>,
@@ -307,15 +324,20 @@ impl<'d, T: AnyInstance> Adc<'d, T> {
             sequence.len() <= 16,
             "Asynchronous read sequence cannot be more than 16 in length"
         );
-        // reset conversions and enable the adc
+        // Ensure no conversions are ongoing
         T::stop();
+        #[cfg(any(adc_g0, adc_v3, adc_h7rs, adc_u0, adc_v4, adc_u5, adc_wba, adc_c0))]
         T::enable();
 
-        //adc side setup
         T::configure_sequence(
             sequence.map(|(channel, sample_time)| ((channel.channel, channel.is_differential), sample_time)),
         );
 
+        // On chips with differential channels, enable after configure_sequence to allow setting differential channels
+        //
+        // TODO: If hardware allows, enable after configure_sequence on all chips
+        #[cfg(any(adc_g4, adc_h5))]
+        T::enable();
         T::configure_dma(ConversionMode::Repeated(mode));
 
         core::mem::forget(self);
diff --git a/embassy-stm32/src/adc/v3.rs b/embassy-stm32/src/adc/v3.rs
index 81eb1e3ee..b270588c4 100644
--- a/embassy-stm32/src/adc/v3.rs
+++ b/embassy-stm32/src/adc/v3.rs
@@ -260,6 +260,9 @@ impl<T: Instance> super::SealedAnyInstance for T {
     }
 
     fn configure_sequence(sequence: impl ExactSizeIterator<Item = ((u8, bool), SampleTime)>) {
+        #[cfg(adc_h5)]
+        T::regs().cr().modify(|w| w.set_aden(false));
+
         // Set sequence length
         #[cfg(not(any(adc_g0, adc_u0)))]
         T::regs().sqr1().modify(|w| {
@@ -294,8 +297,11 @@ impl<T: Instance> super::SealedAnyInstance for T {
             #[cfg(adc_u0)]
             let mut channel_mask = 0;
 
+            #[cfg(adc_h5)]
+            let mut difsel = 0u32;
+
             // Configure channels and ranks
-            for (_i, ((channel, _), sample_time)) in sequence.enumerate() {
+            for (_i, ((channel, _is_differential), sample_time)) in sequence.enumerate() {
                 // RM0492, RM0481, etc.
                 // "This option bit must be set to 1 when ADCx_INP0 or ADCx_INN1 channel is selected."
                 #[cfg(any(adc_h5, adc_h7rs))]
@@ -357,12 +363,20 @@ impl<T: Instance> super::SealedAnyInstance for T {
                     _ => unreachable!(),
                 }
 
+                #[cfg(adc_h5)]
+                {
+                    difsel |= (_is_differential as u32) << channel;
+                }
+
                 #[cfg(adc_u0)]
                 {
                     channel_mask |= 1 << channel;
                 }
             }
 
+            #[cfg(adc_h5)]
+            T::regs().difsel().write(|w| w.set_difsel(difsel));
+
             // On G0 and U0 enabled channels are sampled from 0 to last channel.
             // It is possible to add up to 8 sequences if CHSELRMOD = 1.
             // However for supporting more than 8 channels alternative CHSELRMOD = 0 approach is used.