More ergonomic opamp API, add lock and pga functionality (#113)

* Checkpoint

* Checkpoint

* Example compiles

* Initial lock functionality

* Constrain so opamp output can only be used when configured as an internal output

* Checkpoint

* Checkpoint

* Checkpoint

* Rename opamp structs (correct case)

* Add traits to prelude

* Remove unwrap

* Add remaining PGA modes

* Fix incorrect use of register write (s.b. modify)

* Simplify PGA implementation

* Compiles, some trait duplication

* Simplify a little

* Rename associated types for linter

* Fix additional linter error

Author: stabler

examples/opamp.rs

@@ -5,12 +5,7 @@
 
 use stm32g4xx_hal::adc::AdcClaim;
 use stm32g4xx_hal::adc::ClockSource;
-use stm32g4xx_hal::gpio::gpioa::*;
-use stm32g4xx_hal::gpio::Analog;
-use stm32g4xx_hal::opamp::opamp1::IntoPga as _;
-use stm32g4xx_hal::opamp::opamp2::IntoPga as _;
-use stm32g4xx_hal::opamp::NonInvertingGain;
-use stm32g4xx_hal::opamp::PgaModeInternal;
+use stm32g4xx_hal::opamp::{Gain, InternalOutput};
 use stm32g4xx_hal::prelude::*;
 use stm32g4xx_hal::pwr::PwrExt;
 
@@ -40,32 +35,36 @@ fn main() -> ! {
     let (opamp1, opamp2, opamp3, ..) = dp.OPAMP.split(&mut rcc);
 
     // Set up opamp1 and opamp2 in follower mode
-    let opamp1 = opamp1.follower(gpioa.pa1, Some(gpioa.pa2));
-    let opamp2 = opamp2.follower(gpioa.pa7, Option::<PA6<Analog>>::None);
+    let opamp1 = opamp1.follower(gpioa.pa1, gpioa.pa2);
+    let opamp2 = opamp2.follower(gpioa.pa7, InternalOutput);
 
     // Set up opamp1 and opamp2 in open loop mode
-    let opamp3 = opamp3.open_loop(gpiob.pb0, gpiob.pb2, Some(gpiob.pb1));
+    let opamp3 = opamp3.open_loop(gpiob.pb0, gpiob.pb2, gpiob.pb1);
 
     // disable opamps
-    let (opamp1, pa1, some_pa2) = opamp1.disable();
-    let (opamp2, pa7, _none) = opamp2.disable();
+    let (opamp1, pa1, pa2) = opamp1.disable();
+    let (opamp2, pa7) = opamp2.disable();
 
-    let (_opamp3, _pb0, _pb2, _some_pb1) = opamp3.disable();
+    let (_opamp3, _pb0, _pb2, _pb1) = opamp3.disable();
 
     // Configure opamp1 with pa1 as non-inverting input and set gain to x2
     let _opamp1 = opamp1.pga(
         pa1,
-        PgaModeInternal::gain(NonInvertingGain::Gain2),
-        some_pa2, // Route output to pin pa2
+        pa2, // Route output to pin pa2
+        Gain::Gain2,
     );
 
     // Configure op with pa7 as non-inverting input and set gain to x4
     let opamp2 = opamp2.pga(
         pa7,
-        PgaModeInternal::gain(NonInvertingGain::Gain4),
-        Option::<PA6<Analog>>::None, // Do not route output to any external pin, use internal AD instead
+        InternalOutput, // Do not route output to any external pin, use internal AD instead
+        Gain::Gain4,
     );
 
+    // Lock opamp2. After the opamp is locked its registers cannot be written
+    // until the device is reset (even if using unsafe register accesses).
+    let opamp2 = opamp2.lock();
+
     let mut delay = cp.SYST.delay(&rcc.clocks);
     let mut adc = dp
         .ADC2
@@ -86,8 +85,7 @@ fn main() -> ! {
 
     #[allow(unreachable_code)]
     {
-        let (_opamp1, _pa1, _mode) = _opamp1.disable();
-        let (_opamp2, _pa7, _mode) = opamp2.disable();
+        let (_opamp1, _pin) = _opamp1.disable();
 
         loop {
             delay.delay_ms(100);

src/adc.rs

@@ -13,7 +13,7 @@ pub use crate::time::U32Ext as _;
 use crate::{
     dma::{mux::DmaMuxResources, traits::TargetAddress, PeripheralToMemory},
     gpio::*,
-    opamp,
+    opamp::{self, InternalOutput},
     rcc::{Enable, Rcc, Reset},
     signature::{VtempCal130, VtempCal30, VDDA_CALIB},
     stm32,
@@ -144,21 +144,25 @@ macro_rules! adc_pins {
     };
 }
 
-macro_rules! adc_op_pga {
+macro_rules! adc_opamp {
     ($($opamp:ty => ($adc:ident, $chan:expr)),+ $(,)*) => {
         $(
-            impl<A, B> Channel<stm32::$adc> for $opamp {
+            impl<A> Channel<stm32::$adc> for opamp::Follower<$opamp, A, InternalOutput> {
                 type ID = u8;
                 fn channel() -> u8 { $chan }
             }
-        )+
-    };
-}
 
-macro_rules! adc_op_follower {
-    ($($opamp:ty => ($adc:ident, $chan:expr)),+ $(,)*) => {
-        $(
-            impl<A> Channel<stm32::$adc> for $opamp {
+            impl<A, B> Channel<stm32::$adc> for opamp::OpenLoop<$opamp, A, B, InternalOutput> {
+                type ID = u8;
+                fn channel() -> u8 { $chan }
+            }
+
+            impl<A> Channel<stm32::$adc> for opamp::Pga<$opamp, A, InternalOutput> {
+                type ID = u8;
+                fn channel() -> u8 { $chan }
+            }
+
+            impl Channel<stm32::$adc> for opamp::Locked<$opamp, InternalOutput> {
                 type ID = u8;
                 fn channel() -> u8 { $chan }
             }
@@ -2811,21 +2815,13 @@ adc_pins!(
 );
 
 // See https://www.st.com/resource/en/reference_manual/rm0440-stm32g4-series-advanced-armbased-32bit-mcus-stmicroelectronics.pdf#page=782
-adc_op_pga!(
+adc_opamp!(
     // TODO: Add all opamp types: OpenLoop, Follower(for all opamps)
     // TODO: Should we restrict type parameters A and B?
     // TODO: Also allow AD-channels shared by pins
-    opamp::opamp1::Pga<A, B> => (ADC1, 13),
-    opamp::opamp2::Pga<A, B> => (ADC2, 16),
-
-    opamp::opamp3::Pga<A, B> => (ADC2, 18),
-);
-
-adc_op_follower!(
-    opamp::opamp1::Follower<A> => (ADC1, 13),
-    opamp::opamp2::Follower<A> => (ADC2, 16),
-
-    opamp::opamp3::Follower<A> => (ADC2, 18),
+    opamp::Opamp1 => (ADC1, 13),
+    opamp::Opamp2 => (ADC2, 16),
+    opamp::Opamp3 => (ADC2, 18),
 );
 
 #[cfg(any(
@@ -2836,16 +2832,16 @@ adc_op_follower!(
     feature = "stm32g491",
     feature = "stm32g4a1",
 ))]
-adc_op_pga!(
-    opamp::opamp3::Pga<A, B> => (ADC3, 13),
-    opamp::opamp4::Pga<A, B> => (ADC5, 5),
-    opamp::opamp5::Pga<A, B> => (ADC5, 3),
-    opamp::opamp6::Pga<A, B> => (ADC4, 17),
+adc_opamp!(
+    opamp::Opamp3 => (ADC3, 13),
+    opamp::Opamp4 => (ADC5, 5),
+    opamp::Opamp5 => (ADC5, 3),
+    opamp::Opamp6 => (ADC4, 17),
 );
 
 #[cfg(any(feature = "stm32g491", feature = "stm32g4a1",))]
-adc_op_pga!(
-    opamp::opamp6::Pga<A, B> => (ADC3, 17),
+adc_opamp!(
+    opamp::Opamp6 => (ADC3, 17),
 );
 
 #[cfg(any(feature = "stm32g491", feature = "stm32g4a1",))]