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Merge #879

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879: Improve ADC configuration options r=Dirbaio a=chemicstry

This smooths out a few rough edges with ADC:
- Make `Resolution::to_max_count()` pub for all ADC versions. Useful if performing conversion manually.
- `VREF` and `VREFINT` were convoluted. `VREF` is an external voltage reference used for all ADC conversions and it is exposed as a separate pin on large chips, while on smaller ones it is connected to `VDDA` internally. `VREFINT` is an internal voltage reference connected to one of the ADC channels and can be used to calculate unknown `VREF` voltage.
- Add a separate `VREF_DEFAULT_MV`, equal to 3.3V, which is the usual supply voltage and should work for most simple cases.
  - For an external voltage reference `set_vref()` can be used to set a known precise voltage.
  - If no voltage reference is present, `VREFINT` calibration can be used to calculate unknown `VREF` voltage. If I understand correctly, this is only implemented for `adc_v3` (L4?), but is not currently exposed (private). If someone is interested, this can be fixed in separate PR.

Co-authored-by: chemicstry <chemicstry@gmail.com>
This commit is contained in:
bors[bot] 2022-07-27 12:41:03 +00:00 committed by GitHub
commit 9af68e005b
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4 changed files with 68 additions and 34 deletions
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26
embassy-stm32/src/adc/v2.rs
View File

@ -7,7 +7,10 @@ use crate::adc::{AdcPin, Instance};
use crate::time::Hertz;
use crate::Peripheral;
pub const VDDA_CALIB_MV: u32 = 3000;
/// Default VREF voltage used for sample conversion to millivolts.
pub const VREF_DEFAULT_MV: u32 = 3300;
/// VREF voltage used for factory calibration of VREFINTCAL register.
pub const VREF_CALIB_MV: u32 = 3300;
#[cfg(not(any(rcc_f4, rcc_f7)))]
fn enable() {
@ -47,7 +50,7 @@ impl Resolution {
}
}
fn to_max_count(&self) -> u32 {
pub fn to_max_count(&self) -> u32 {
match self {
Resolution::TwelveBit => (1 << 12) - 1,
Resolution::TenBit => (1 << 10) - 1,
@ -57,9 +60,9 @@ impl Resolution {
}
}
pub struct Vref;
impl<T: Instance> AdcPin<T> for Vref {}
impl<T: Instance> super::sealed::AdcPin<T> for Vref {
pub struct VrefInt;
impl<T: Instance> AdcPin<T> for VrefInt {}
impl<T: Instance> super::sealed::AdcPin<T> for VrefInt {
fn channel(&self) -> u8 {
17
}
@ -150,7 +153,7 @@ impl Prescaler {
pub struct Adc<'d, T: Instance> {
sample_time: SampleTime,
calibrated_vdda: u32,
vref_mv: u32,
resolution: Resolution,
phantom: PhantomData<&'d mut T>,
}
@ -180,7 +183,7 @@ where
Self {
sample_time: Default::default(),
resolution: Resolution::default(),
calibrated_vdda: VDDA_CALIB_MV,
vref_mv: VREF_DEFAULT_MV,
phantom: PhantomData,
}
}
@ -193,9 +196,16 @@ where
self.resolution = resolution;
}
/// Set VREF value in millivolts. This value is used for [to_millivolts()] sample conversion.
///
/// Use this if you have a known precise VREF (VDDA) pin reference voltage.
pub fn set_vref_mv(&mut self, vref_mv: u32) {
self.vref_mv = vref_mv;
}
/// Convert a measurement to millivolts
pub fn to_millivolts(&self, sample: u16) -> u16 {
((u32::from(sample) * self.calibrated_vdda) / self.resolution.to_max_count()) as u16
((u32::from(sample) * self.vref_mv) / self.resolution.to_max_count()) as u16
}
/// Perform a single conversion.

42
embassy-stm32/src/adc/v3.rs
View File

@ -6,7 +6,10 @@ use embedded_hal_02::blocking::delay::DelayUs;
use crate::adc::{AdcPin, Instance};
use crate::Peripheral;
pub const VDDA_CALIB_MV: u32 = 3000;
/// Default VREF voltage used for sample conversion to millivolts.
pub const VREF_DEFAULT_MV: u32 = 3300;
/// VREF voltage used for factory calibration of VREFINTCAL register.
pub const VREF_CALIB_MV: u32 = 3000;
/// Sadly we cannot use `RccPeripheral::enable` since devices are quite inconsistent ADC clock
/// configuration.
@ -44,7 +47,7 @@ impl Resolution {
}
}
fn to_max_count(&self) -> u32 {
pub fn to_max_count(&self) -> u32 {
match self {
Resolution::TwelveBit => (1 << 12) - 1,
Resolution::TenBit => (1 << 10) - 1,
@ -54,9 +57,9 @@ impl Resolution {
}
}
pub struct Vref;
impl<T: Instance> AdcPin<T> for Vref {}
impl<T: Instance> super::sealed::AdcPin<T> for Vref {
pub struct VrefInt;
impl<T: Instance> AdcPin<T> for VrefInt {}
impl<T: Instance> super::sealed::AdcPin<T> for VrefInt {
fn channel(&self) -> u8 {
#[cfg(not(stm32g0))]
let val = 0;
@ -202,7 +205,7 @@ pub use sample_time::SampleTime;
pub struct Adc<'d, T: Instance> {
sample_time: SampleTime,
calibrated_vdda: u32,
vref_mv: u32,
resolution: Resolution,
phantom: PhantomData<&'d mut T>,
}
@ -241,12 +244,12 @@ impl<'d, T: Instance> Adc<'d, T> {
Self {
sample_time: Default::default(),
resolution: Resolution::default(),
calibrated_vdda: VDDA_CALIB_MV,
vref_mv: VREF_DEFAULT_MV,
phantom: PhantomData,
}
}
pub fn enable_vref(&self, delay: &mut impl DelayUs<u32>) -> Vref {
pub fn enable_vrefint(&self, delay: &mut impl DelayUs<u32>) -> VrefInt {
unsafe {
T::common_regs().ccr().modify(|reg| {
reg.set_vrefen(true);
@ -259,7 +262,7 @@ impl<'d, T: Instance> Adc<'d, T> {
//cortex_m::asm::delay(20_000_000);
delay.delay_us(15);
Vref {}
VrefInt {}
}
pub fn enable_temperature(&self) -> Temperature {
@ -282,16 +285,16 @@ impl<'d, T: Instance> Adc<'d, T> {
Vbat {}
}
/// Calculates the system VDDA by sampling the internal VREF channel and comparing
/// Calculates the system VDDA by sampling the internal VREFINT channel and comparing
/// the result with the value stored at the factory. If the chip's VDDA is not stable, run
/// this before each ADC conversion.
#[cfg(not(stm32g0))] // TODO is this supposed to be public?
#[allow(unused)] // TODO is this supposed to be public?
fn calibrate(&mut self, vref: &mut Vref) {
fn calibrate(&mut self, vrefint: &mut VrefInt) {
#[cfg(stm32l5)]
let vref_cal: u32 = todo!();
let vrefint_cal: u32 = todo!();
#[cfg(not(stm32l5))]
let vref_cal = unsafe { crate::pac::VREFINTCAL.data().read().value() };
let vrefint_cal = unsafe { crate::pac::VREFINTCAL.data().read().value() };
let old_sample_time = self.sample_time;
// "Table 24. Embedded internal voltage reference" states that the sample time needs to be
@ -300,11 +303,11 @@ impl<'d, T: Instance> Adc<'d, T> {
self.sample_time = SampleTime::Cycles640_5;
// This can't actually fail, it's just in a result to satisfy hal trait
let vref_samp = self.read(vref);
let vrefint_samp = self.read(vrefint);
self.sample_time = old_sample_time;
self.calibrated_vdda = (VDDA_CALIB_MV * u32::from(vref_cal)) / u32::from(vref_samp);
self.vref_mv = (VREF_CALIB_MV * u32::from(vrefint_cal)) / u32::from(vrefint_samp);
}
pub fn set_sample_time(&mut self, sample_time: SampleTime) {
@ -315,9 +318,16 @@ impl<'d, T: Instance> Adc<'d, T> {
self.resolution = resolution;
}
/// Set VREF value in millivolts. This value is used for [to_millivolts()] sample conversion.
///
/// Use this if you have a known precise VREF (VDDA) pin reference voltage.
pub fn set_vref_mv(&mut self, vref_mv: u32) {
self.vref_mv = vref_mv;
}
/// Convert a measurement to millivolts
pub fn to_millivolts(&self, sample: u16) -> u16 {
((u32::from(sample) * self.calibrated_vdda) / self.resolution.to_max_count()) as u16
((u32::from(sample) * self.vref_mv) / self.resolution.to_max_count()) as u16
}
/*

28
embassy-stm32/src/adc/v4.rs
View File

@ -9,6 +9,11 @@ use super::{AdcPin, Instance};
use crate::time::Hertz;
use crate::{pac, Peripheral};
/// Default VREF voltage used for sample conversion to millivolts.
pub const VREF_DEFAULT_MV: u32 = 3300;
/// VREF voltage used for factory calibration of VREFINTCAL register.
pub const VREF_CALIB_MV: u32 = 3300;
pub enum Resolution {
SixteenBit,
FourteenBit,
@ -53,10 +58,10 @@ mod sealed {
}
}
// NOTE: Vref/Temperature/Vbat are only available on ADC3 on H7, this currently cannot be modeled with stm32-data, so these are available from the software on all ADCs
pub struct Vref;
impl<T: Instance> InternalChannel<T> for Vref {}
impl<T: Instance> sealed::InternalChannel<T> for Vref {
// NOTE: Vrefint/Temperature/Vbat are only available on ADC3 on H7, this currently cannot be modeled with stm32-data, so these are available from the software on all ADCs
pub struct VrefInt;
impl<T: Instance> InternalChannel<T> for VrefInt {}
impl<T: Instance> sealed::InternalChannel<T> for VrefInt {
fn channel(&self) -> u8 {
19
}
@ -317,6 +322,7 @@ impl Prescaler {
pub struct Adc<'d, T: Instance> {
sample_time: SampleTime,
vref_mv: u32,
resolution: Resolution,
phantom: PhantomData<&'d mut T>,
}
@ -354,6 +360,7 @@ impl<'d, T: Instance + crate::rcc::RccPeripheral> Adc<'d, T> {
let mut s = Self {
sample_time: Default::default(),
vref_mv: VREF_DEFAULT_MV,
resolution: Resolution::default(),
phantom: PhantomData,
};
@ -422,14 +429,14 @@ impl<'d, T: Instance + crate::rcc::RccPeripheral> Adc<'d, T> {
}
}
pub fn enable_vref(&self) -> Vref {
pub fn enable_vrefint(&self) -> VrefInt {
unsafe {
T::common_regs().ccr().modify(|reg| {
reg.set_vrefen(true);
});
}
Vref {}
VrefInt {}
}
pub fn enable_temperature(&self) -> Temperature {
@ -460,9 +467,16 @@ impl<'d, T: Instance + crate::rcc::RccPeripheral> Adc<'d, T> {
self.resolution = resolution;
}
/// Set VREF value in millivolts. This value is used for [to_millivolts()] sample conversion.
///
/// Use this if you have a known precise VREF (VDDA) pin reference voltage.
pub fn set_vref_mv(&mut self, vref_mv: u32) {
self.vref_mv = vref_mv;
}
/// Convert a measurement to millivolts
pub fn to_millivolts(&self, sample: u16) -> u16 {
((u32::from(sample) * 3300) / self.resolution.to_max_count()) as u16
((u32::from(sample) * self.vref_mv) / self.resolution.to_max_count()) as u16
}
/// Perform a single conversion.

6
examples/stm32h7/src/bin/adc.rs
View File

@ -28,11 +28,11 @@ async fn main(_spawner: Spawner, mut p: Peripherals) {
adc.set_sample_time(SampleTime::Cycles32_5);
let mut vref_channel = adc.enable_vref();
let mut vrefint_channel = adc.enable_vrefint();
loop {
let vref = adc.read_internal(&mut vref_channel);
info!("vref: {}", vref);
let vrefint = adc.read_internal(&mut vrefint_channel);
info!("vrefint: {}", vrefint);
let measured = adc.read(&mut p.PC0);
info!("measured: {}", measured);
Timer::after(Duration::from_millis(500)).await;