3 files changed, 341 insertions, 22 deletions

diff --git a/embassy-stm32/build.rs b/embassy-stm32/build.rs
index d965d8732..19851ee66 100644
--- a/embassy-stm32/build.rs
+++ b/embassy-stm32/build.rs
@@ -1338,6 +1338,18 @@ fn main() {
                         g.extend(quote! {
                             impl_opamp_vp_pin!( #peri, #pin_name, #ch);
                         })
+                    } else if pin.signal.starts_with("VINM") {
+                        // Impl NonInvertingPin for the VINM* signals ( VINM0, VINM1, etc)
+                        // STM32G4
+                        let peri = format_ident!("{}", p.name);
+                        let pin_name = format_ident!("{}", pin.pin);
+                        let ch: Result<u8, _> = pin.signal.strip_prefix("VINM").unwrap().parse();
+
+                        if let Ok(ch) = ch {
+                            g.extend(quote! {
+                                impl_opamp_vn_pin!( #peri, #pin_name, #ch);
+                            })
+                        }
                     } else if pin.signal == "VOUT" {
                         // Impl OutputPin for the VOUT pin
                         let peri = format_ident!("{}", p.name);
diff --git a/embassy-stm32/src/opamp.rs b/embassy-stm32/src/opamp.rs
index a81493c1b..82de4a89b 100644
--- a/embassy-stm32/src/opamp.rs
+++ b/embassy-stm32/src/opamp.rs
@@ -6,15 +6,33 @@ use embassy_hal_internal::PeripheralType;
 use crate::pac::opamp::vals::*;
 use crate::Peri;
 
+/// Performs a busy-wait delay for a specified number of microseconds.
+#[cfg(opamp_g4)]
+fn blocking_delay_ms(ms: u32) {
+    #[cfg(feature = "time")]
+    embassy_time::block_for(embassy_time::Duration::from_millis(ms as u64));
+    #[cfg(not(feature = "time"))]
+    cortex_m::asm::delay(unsafe { crate::rcc::get_freqs() }.sys.to_hertz().unwrap().0 / 1_000 * ms);
+}
+
 /// Gain
 #[allow(missing_docs)]
 #[derive(Clone, Copy)]
 pub enum OpAmpGain {
-    Mul1,
     Mul2,
     Mul4,
     Mul8,
     Mul16,
+    #[cfg(opamp_g4)]
+    Mul32,
+    #[cfg(opamp_g4)]
+    Mul64,
+}
+
+#[cfg(opamp_g4)]
+enum OpAmpDifferentialPair {
+    P,
+    N,
 }
 
 /// Speed
@@ -82,24 +100,71 @@ impl<'d, T: Instance> OpAmp<'d, T> {
         &mut self,
         in_pin: Peri<'_, impl NonInvertingPin<T> + crate::gpio::Pin>,
         out_pin: Peri<'_, impl OutputPin<T> + crate::gpio::Pin>,
+    ) -> OpAmpOutput<'_, T> {
+        in_pin.set_as_analog();
+        out_pin.set_as_analog();
+
+        #[cfg(opamp_g4)]
+        let vm_sel = VmSel::OUTPUT;
+        #[cfg(not(opamp_g4))]
+        let vm_sel = VmSel::from_bits(0b11);
+
+        T::regs().csr().modify(|w| {
+            w.set_vp_sel(VpSel::from_bits(in_pin.channel()));
+            w.set_vm_sel(vm_sel);
+            #[cfg(opamp_g4)]
+            w.set_opaintoen(Opaintoen::OUTPUT_PIN);
+            w.set_opampen(true);
+        });
+
+        OpAmpOutput { _inner: self }
+    }
+
+    /// Configure the OpAmp as a PGA for the provided input pin,
+    /// outputting to the provided output pin, and enable the opamp.
+    ///
+    /// The input pin is configured for analogue mode but not consumed,
+    /// so it may subsequently be used for ADC or comparator inputs.
+    ///
+    /// The output pin is held within the returned [`OpAmpOutput`] struct,
+    /// preventing it being used elsewhere. The `OpAmpOutput` can then be
+    /// directly used as an ADC input. The opamp will be disabled when the
+    /// [`OpAmpOutput`] is dropped.
+    pub fn pga_ext(
+        &mut self,
+        in_pin: Peri<'_, impl NonInvertingPin<T> + crate::gpio::Pin>,
+        out_pin: Peri<'_, impl OutputPin<T> + crate::gpio::Pin>,
         gain: OpAmpGain,
     ) -> OpAmpOutput<'_, T> {
         in_pin.set_as_analog();
         out_pin.set_as_analog();
 
-        // PGA_GAIN value may have different meaning in different MCU serials, use with caution.
-        let (vm_sel, pga_gain) = match gain {
-            OpAmpGain::Mul1 => (0b11, 0b00),
-            OpAmpGain::Mul2 => (0b10, 0b00),
-            OpAmpGain::Mul4 => (0b10, 0b01),
-            OpAmpGain::Mul8 => (0b10, 0b10),
-            OpAmpGain::Mul16 => (0b10, 0b11),
+        #[cfg(opamp_g4)]
+        let vm_sel = VmSel::PGA;
+        #[cfg(not(opamp_g4))]
+        let vm_sel = VmSel::from_bits(0b10);
+
+        #[cfg(opamp_g4)]
+        let pga_gain = match gain {
+            OpAmpGain::Mul2 => PgaGain::GAIN2,
+            OpAmpGain::Mul4 => PgaGain::GAIN4,
+            OpAmpGain::Mul8 => PgaGain::GAIN8,
+            OpAmpGain::Mul16 => PgaGain::GAIN16,
+            OpAmpGain::Mul32 => PgaGain::GAIN32,
+            OpAmpGain::Mul64 => PgaGain::GAIN64,
         };
+        #[cfg(not(opamp_g4))]
+        let pga_gain = PgaGain::from_bits(match gain {
+            OpAmpGain::Mul2 => 0b00,
+            OpAmpGain::Mul4 => 0b01,
+            OpAmpGain::Mul8 => 0b10,
+            OpAmpGain::Mul16 => 0b11,
+        });
 
         T::regs().csr().modify(|w| {
             w.set_vp_sel(VpSel::from_bits(in_pin.channel()));
-            w.set_vm_sel(VmSel::from_bits(vm_sel));
-            w.set_pga_gain(PgaGain::from_bits(pga_gain));
+            w.set_vm_sel(vm_sel);
+            w.set_pga_gain(pga_gain);
             #[cfg(opamp_g4)]
             w.set_opaintoen(Opaintoen::OUTPUT_PIN);
             w.set_opampen(true);
@@ -107,6 +172,7 @@ impl<'d, T: Instance> OpAmp<'d, T> {
 
         OpAmpOutput { _inner: self }
     }
+
     /// Configure the OpAmp as a buffer for the DAC it is connected to,
     /// outputting to the provided output pin, and enable the opamp.
     ///
@@ -142,30 +208,259 @@ impl<'d, T: Instance> OpAmp<'d, T> {
     pub fn buffer_int(
         &mut self,
         pin: Peri<'_, impl NonInvertingPin<T> + crate::gpio::Pin>,
+    ) -> OpAmpInternalOutput<'_, T> {
+        pin.set_as_analog();
+
+        T::regs().csr().modify(|w| {
+            w.set_vp_sel(VpSel::from_bits(pin.channel()));
+            w.set_vm_sel(VmSel::OUTPUT);
+            #[cfg(opamp_g4)]
+            w.set_opaintoen(Opaintoen::ADCCHANNEL);
+            w.set_opampen(true);
+        });
+
+        OpAmpInternalOutput { _inner: self }
+    }
+
+    /// Configure the OpAmp as a PGA for the provided input pin,
+    /// with the output only used internally, and enable the opamp.
+    ///
+    /// The input pin is configured for analogue mode but not consumed,
+    /// so it may be subsequently used for ADC or comparator inputs.
+    ///
+    /// The returned `OpAmpInternalOutput` struct may be used as an ADC input.
+    /// The opamp output will be disabled when it is dropped.
+    #[cfg(opamp_g4)]
+    pub fn pga_int(
+        &mut self,
+        pin: Peri<'_, impl NonInvertingPin<T> + crate::gpio::Pin>,
         gain: OpAmpGain,
     ) -> OpAmpInternalOutput<'_, T> {
         pin.set_as_analog();
 
-        // PGA_GAIN value may have different meaning in different MCU serials, use with caution.
-        let (vm_sel, pga_gain) = match gain {
-            OpAmpGain::Mul1 => (0b11, 0b00),
-            OpAmpGain::Mul2 => (0b10, 0b00),
-            OpAmpGain::Mul4 => (0b10, 0b01),
-            OpAmpGain::Mul8 => (0b10, 0b10),
-            OpAmpGain::Mul16 => (0b10, 0b11),
+        let pga_gain = match gain {
+            OpAmpGain::Mul2 => PgaGain::GAIN2,
+            OpAmpGain::Mul4 => PgaGain::GAIN4,
+            OpAmpGain::Mul8 => PgaGain::GAIN8,
+            OpAmpGain::Mul16 => PgaGain::GAIN16,
+            OpAmpGain::Mul32 => PgaGain::GAIN32,
+            OpAmpGain::Mul64 => PgaGain::GAIN64,
         };
 
         T::regs().csr().modify(|w| {
-            use crate::pac::opamp::vals::*;
             w.set_vp_sel(VpSel::from_bits(pin.channel()));
-            w.set_vm_sel(VmSel::from_bits(vm_sel));
-            w.set_pga_gain(PgaGain::from_bits(pga_gain));
+            w.set_vm_sel(VmSel::OUTPUT);
+            w.set_pga_gain(pga_gain);
             w.set_opaintoen(Opaintoen::ADCCHANNEL);
             w.set_opampen(true);
         });
 
         OpAmpInternalOutput { _inner: self }
     }
+
+    /// Configure the OpAmp as a standalone DAC with the inverting input
+    /// connected to the provided pin, and the output is connected
+    /// internally to an ADC channel.
+    ///
+    /// The input pin is configured for analogue mode but not consumed,
+    /// so it may be subsequently used for ADC or comparator inputs.
+    ///
+    /// The returned `OpAmpInternalOutput` struct may be used as an ADC
+    /// input. The opamp output will be disabled when it is dropped.
+    #[cfg(opamp_g4)]
+    pub fn standalone_dac_int(
+        &mut self,
+        m_pin: Peri<'_, impl InvertingPin<T> + crate::gpio::Pin>,
+    ) -> OpAmpInternalOutput<'_, T> {
+        m_pin.set_as_analog();
+
+        T::regs().csr().modify(|w| {
+            use crate::pac::opamp::vals::*;
+            w.set_vp_sel(VpSel::DAC3_CH1); // Actually DAC3_CHx
+            w.set_vm_sel(VmSel::from_bits(m_pin.channel()));
+            w.set_opaintoen(Opaintoen::ADCCHANNEL);
+            w.set_opampen(true);
+        });
+
+        OpAmpInternalOutput { _inner: self }
+    }
+
+    /// Configure the OpAmp as a standalone DAC with the inverting input
+    /// connected to the provided pin, and the output connected to the
+    /// provided pin.
+    ///
+    /// The input pin is configured for analogue mode but not consumed,
+    /// so it may be subsequently used for ADC or comparator inputs.
+    ///
+    /// The output pin is held within the returned [`OpAmpOutput`] struct,
+    /// preventing it being used elsewhere. The opamp will be disabled when
+    /// the [`OpAmpOutput`] is dropped.
+    #[cfg(opamp_g4)]
+    pub fn standalone_dac_ext(
+        &mut self,
+        m_pin: Peri<'_, impl InvertingPin<T> + crate::gpio::Pin>,
+        out_pin: Peri<'_, impl OutputPin<T> + crate::gpio::Pin>,
+    ) -> OpAmpOutput<'_, T> {
+        m_pin.set_as_analog();
+        out_pin.set_as_analog();
+
+        T::regs().csr().modify(|w| {
+            use crate::pac::opamp::vals::*;
+            w.set_vp_sel(VpSel::DAC3_CH1); // Actually DAC3_CHx
+            w.set_vm_sel(VmSel::from_bits(m_pin.channel()));
+            w.set_opaintoen(Opaintoen::OUTPUT_PIN);
+            w.set_opampen(true);
+        });
+
+        OpAmpOutput { _inner: self }
+    }
+
+    /// Configure the OpAmp in standalone mode with the non-inverting input
+    /// connected to the provided `p_pin`, the inverting input connected to
+    /// the `m_pin`, and output to the provided `out_pin`.
+    ///
+    /// The input pins are configured for analogue mode but not consumed,
+    /// allowing their subsequent use for ADC or comparator inputs.
+    ///
+    /// The output pin is held within the returned [`OpAmpOutput`] struct,
+    /// preventing it being used elsewhere. The opamp will be disabled when
+    /// the [`OpAmpOutput`] is dropped.
+    #[cfg(opamp_g4)]
+    pub fn standalone_ext(
+        &mut self,
+        p_pin: Peri<'d, impl NonInvertingPin<T> + crate::gpio::Pin>,
+        m_pin: Peri<'d, impl InvertingPin<T> + crate::gpio::Pin>,
+        out_pin: Peri<'d, impl OutputPin<T> + crate::gpio::Pin>,
+    ) -> OpAmpOutput<'_, T> {
+        p_pin.set_as_analog();
+        m_pin.set_as_analog();
+        out_pin.set_as_analog();
+
+        T::regs().csr().modify(|w| {
+            use crate::pac::opamp::vals::*;
+            w.set_vp_sel(VpSel::from_bits(p_pin.channel()));
+            w.set_vm_sel(VmSel::from_bits(m_pin.channel()));
+            w.set_opaintoen(Opaintoen::OUTPUT_PIN);
+            w.set_opampen(true);
+        });
+
+        OpAmpOutput { _inner: self }
+    }
+
+    /// Configure the OpAmp in standalone mode with the non-inverting input
+    /// connected to the provided `p_pin`, the inverting input connected to
+    /// the `m_pin`, and output is connected to the DAC.
+    ///
+    /// The input pins are configured for analogue mode but not consumed,
+    /// allowing their subsequent use for ADC or comparator inputs.
+    ///
+    /// The returned `OpAmpOutput` struct may be used as an ADC
+    /// input. The opamp output will be disabled when it is dropped.
+    #[cfg(opamp_g4)]
+    pub fn standalone_int(
+        &mut self,
+        p_pin: Peri<'d, impl NonInvertingPin<T> + crate::gpio::Pin>,
+        m_pin: Peri<'d, impl InvertingPin<T> + crate::gpio::Pin>,
+    ) -> OpAmpOutput<'_, T> {
+        p_pin.set_as_analog();
+        m_pin.set_as_analog();
+
+        T::regs().csr().modify(|w| {
+            use crate::pac::opamp::vals::*;
+            w.set_vp_sel(VpSel::from_bits(p_pin.channel()));
+            w.set_vm_sel(VmSel::from_bits(m_pin.channel()));
+            w.set_opaintoen(Opaintoen::ADCCHANNEL);
+            w.set_opampen(true);
+        });
+
+        OpAmpOutput { _inner: self }
+    }
+
+    /// Calibrates the operational amplifier.
+    ///
+    /// This function enables the opamp and sets the user trim mode for calibration.
+    /// Depending on the speed mode of the opamp, it calibrates the differential pair inputs.
+    /// For normal speed, both the P and N differential pairs are calibrated,
+    /// while for high-speed mode, only the P differential pair is calibrated.
+    ///
+    /// Calibrating a differential pair requires waiting 12ms in the worst case (binary method).
+    #[cfg(opamp_g4)]
+    pub fn calibrate(&mut self) {
+        T::regs().csr().modify(|w| {
+            w.set_opampen(true);
+            w.set_calon(true);
+            w.set_usertrim(Usertrim::USER);
+        });
+
+        match T::regs().csr().read().opahsm() {
+            Opahsm::NORMAL => {
+                self.calibrate_differential_pair(OpAmpDifferentialPair::P);
+                self.calibrate_differential_pair(OpAmpDifferentialPair::N);
+            }
+            Opahsm::HIGH_SPEED => {
+                self.calibrate_differential_pair(OpAmpDifferentialPair::P);
+            }
+        }
+
+        T::regs().csr().modify(|w| {
+            w.set_calon(false);
+            w.set_opampen(false);
+        });
+    }
+
+    /// Calibrate differential pair.
+    ///
+    /// The calibration is done by trying different offset values and
+    /// measuring the outcal bit.
+    ///
+    /// The calibration range is from 0 to 31.
+    ///
+    /// The result is stored in the OPAMP_CSR register.
+    #[cfg(opamp_g4)]
+    fn calibrate_differential_pair(&mut self, pair: OpAmpDifferentialPair) {
+        let mut low = 0;
+        let mut high = 31;
+
+        let calsel = match pair {
+            OpAmpDifferentialPair::P => Calsel::PERCENT10,
+            OpAmpDifferentialPair::N => Calsel::PERCENT90,
+        };
+
+        T::regs().csr().modify(|w| {
+            w.set_calsel(calsel);
+        });
+
+        while low <= high {
+            let mid = (low + high) / 2;
+
+            T::regs().csr().modify(|w| match pair {
+                OpAmpDifferentialPair::P => {
+                    defmt::info!("p calibration. offset: {}", mid);
+                    w.set_trimoffsetp(mid);
+                }
+                OpAmpDifferentialPair::N => {
+                    defmt::info!("n calibration. offset: {}", mid);
+                    w.set_trimoffsetn(mid);
+                }
+            });
+
+            // The closer the trimming value is to the optimum trimming value, the longer it takes to stabilize
+            // (with a maximum stabilization time remaining below 2 ms in any case) -- RM0440 25.3.7
+            blocking_delay_ms(2);
+
+            if T::regs().csr().read().outcal() == Outcal::LOW {
+                if mid == 0 {
+                    break;
+                }
+                high = mid - 1;
+            } else {
+                if mid == 31 {
+                    break;
+                }
+                low = mid + 1;
+            }
+        }
+    }
 }
 
 impl<'d, T: Instance> Drop for OpAmpOutput<'d, T> {
@@ -339,6 +634,18 @@ macro_rules! impl_opamp_vp_pin {
 }
 
 #[allow(unused_macros)]
+macro_rules! impl_opamp_vn_pin {
+    ($inst:ident, $pin:ident, $ch:expr) => {
+        impl crate::opamp::InvertingPin<peripherals::$inst> for crate::peripherals::$pin {}
+        impl crate::opamp::SealedInvertingPin<peripherals::$inst> for crate::peripherals::$pin {
+            fn channel(&self) -> u8 {
+                $ch
+            }
+        }
+    };
+}
+
+#[allow(unused_macros)]
 macro_rules! impl_opamp_vout_pin {
     ($inst:ident, $pin:ident) => {
         impl crate::opamp::OutputPin<peripherals::$inst> for crate::peripherals::$pin {}
diff --git a/examples/stm32f334/src/bin/opamp.rs b/examples/stm32f334/src/bin/opamp.rs
index b30445ead..c344935d7 100644
--- a/examples/stm32f334/src/bin/opamp.rs
+++ b/examples/stm32f334/src/bin/opamp.rs
@@ -4,7 +4,7 @@
 use defmt::info;
 use embassy_executor::Spawner;
 use embassy_stm32::adc::{Adc, SampleTime};
-use embassy_stm32::opamp::{OpAmp, OpAmpGain};
+use embassy_stm32::opamp::OpAmp;
 use embassy_stm32::peripherals::ADC2;
 use embassy_stm32::time::mhz;
 use embassy_stm32::{adc, bind_interrupts, Config};
@@ -48,7 +48,7 @@ async fn main(_spawner: Spawner) -> ! {
 
     let mut vrefint = adc.enable_vref();
     let mut temperature = adc.enable_temperature();
-    let mut buffer = opamp.buffer_ext(p.PA7.reborrow(), p.PA6.reborrow(), OpAmpGain::Mul1);
+    let mut buffer = opamp.buffer_ext(p.PA7.reborrow(), p.PA6.reborrow());
 
     loop {
         let vref = adc.read(&mut vrefint).await;