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adc.rs
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adc.rs
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//! ADC driver.
use core::future::poll_fn;
use core::marker::PhantomData;
use core::mem;
use core::sync::atomic::{compiler_fence, Ordering};
use core::task::Poll;
use embassy_hal_internal::{into_ref, PeripheralRef};
use embassy_sync::waitqueue::AtomicWaker;
use crate::gpio::{self, AnyPin, Pull, SealedPin as GpioPin};
use crate::interrupt::typelevel::Binding;
use crate::interrupt::InterruptExt;
use crate::peripherals::{ADC, ADC_TEMP_SENSOR};
use crate::{dma, interrupt, pac, peripherals, Peripheral, RegExt};
static WAKER: AtomicWaker = AtomicWaker::new();
/// ADC config.
#[non_exhaustive]
#[derive(Default)]
pub struct Config {}
enum Source<'p> {
Pin(PeripheralRef<'p, AnyPin>),
TempSensor(PeripheralRef<'p, ADC_TEMP_SENSOR>),
}
/// ADC channel.
pub struct Channel<'p>(Source<'p>);
impl<'p> Channel<'p> {
/// Create a new ADC channel from pin with the provided [Pull] configuration.
pub fn new_pin(pin: impl Peripheral<P = impl AdcPin + 'p> + 'p, pull: Pull) -> Self {
into_ref!(pin);
pin.pad_ctrl().modify(|w| {
// manual says:
//
// > When using an ADC input shared with a GPIO pin, the pin’s
// > digital functions must be disabled by setting IE low and OD
// > high in the pin’s pad control register
w.set_ie(false);
w.set_od(true);
w.set_pue(pull == Pull::Up);
w.set_pde(pull == Pull::Down);
});
Self(Source::Pin(pin.map_into()))
}
/// Create a new ADC channel for the internal temperature sensor.
pub fn new_temp_sensor(s: impl Peripheral<P = ADC_TEMP_SENSOR> + 'p) -> Self {
let r = pac::ADC;
r.cs().write_set(|w| w.set_ts_en(true));
Self(Source::TempSensor(s.into_ref()))
}
fn channel(&self) -> u8 {
match &self.0 {
// this requires adc pins to be sequential and matching the adc channels,
// which is the case for rp2040
Source::Pin(p) => p._pin() - 26,
Source::TempSensor(_) => 4,
}
}
}
impl<'p> Drop for Source<'p> {
fn drop(&mut self) {
match self {
Source::Pin(p) => {
p.pad_ctrl().modify(|w| {
w.set_ie(true);
w.set_od(false);
w.set_pue(false);
w.set_pde(true);
});
}
Source::TempSensor(_) => {
pac::ADC.cs().write_clear(|w| w.set_ts_en(true));
}
}
}
}
/// ADC sample.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Default)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[repr(transparent)]
pub struct Sample(u16);
impl Sample {
/// Sample is valid.
pub fn good(&self) -> bool {
self.0 < 0x8000
}
/// Sample value.
pub fn value(&self) -> u16 {
self.0 & !0x8000
}
}
/// ADC error.
#[derive(Debug, Eq, PartialEq, Copy, Clone)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub enum Error {
/// Error converting value.
ConversionFailed,
}
/// ADC mode.
pub trait Mode {}
/// ADC async mode.
pub struct Async;
impl Mode for Async {}
/// ADC blocking mode.
pub struct Blocking;
impl Mode for Blocking {}
/// ADC driver.
pub struct Adc<'d, M: Mode> {
phantom: PhantomData<(&'d ADC, M)>,
}
impl<'d, M: Mode> Drop for Adc<'d, M> {
fn drop(&mut self) {
let r = Self::regs();
// disable ADC. leaving it enabled comes with a ~150µA static
// current draw. the temperature sensor has already been disabled
// by the temperature-reading methods, so we don't need to touch that.
r.cs().write(|w| w.set_en(false));
}
}
impl<'d, M: Mode> Adc<'d, M> {
#[inline]
fn regs() -> pac::adc::Adc {
pac::ADC
}
#[inline]
fn reset() -> pac::resets::regs::Peripherals {
let mut ret = pac::resets::regs::Peripherals::default();
ret.set_adc(true);
ret
}
fn setup() {
let reset = Self::reset();
crate::reset::reset(reset);
crate::reset::unreset_wait(reset);
let r = Self::regs();
// Enable ADC
r.cs().write(|w| w.set_en(true));
// Wait for ADC ready
while !r.cs().read().ready() {}
}
/// Sample a value from a channel in blocking mode.
pub fn blocking_read(&mut self, ch: &mut Channel) -> Result<u16, Error> {
let r = Self::regs();
r.cs().modify(|w| {
w.set_ainsel(ch.channel());
w.set_start_once(true);
w.set_err(true);
});
while !r.cs().read().ready() {}
match r.cs().read().err() {
true => Err(Error::ConversionFailed),
false => Ok(r.result().read().result()),
}
}
}
impl<'d> Adc<'d, Async> {
/// Create ADC driver in async mode.
pub fn new(
_inner: impl Peripheral<P = ADC> + 'd,
_irq: impl Binding<interrupt::typelevel::ADC_IRQ_FIFO, InterruptHandler>,
_config: Config,
) -> Self {
Self::setup();
// Setup IRQ
interrupt::ADC_IRQ_FIFO.unpend();
unsafe { interrupt::ADC_IRQ_FIFO.enable() };
Self { phantom: PhantomData }
}
async fn wait_for_ready() {
let r = Self::regs();
r.inte().write(|w| w.set_fifo(true));
compiler_fence(Ordering::SeqCst);
poll_fn(|cx| {
WAKER.register(cx.waker());
if r.cs().read().ready() {
return Poll::Ready(());
}
Poll::Pending
})
.await;
}
/// Sample a value from a channel until completed.
pub async fn read(&mut self, ch: &mut Channel<'_>) -> Result<u16, Error> {
let r = Self::regs();
r.cs().modify(|w| {
w.set_ainsel(ch.channel());
w.set_start_once(true);
w.set_err(true);
});
Self::wait_for_ready().await;
match r.cs().read().err() {
true => Err(Error::ConversionFailed),
false => Ok(r.result().read().result()),
}
}
async fn read_many_inner<W: dma::Word>(
&mut self,
ch: &mut Channel<'_>,
buf: &mut [W],
fcs_err: bool,
div: u16,
dma: impl Peripheral<P = impl dma::Channel>,
) -> Result<(), Error> {
let r = Self::regs();
// clear previous errors and set channel
r.cs().modify(|w| {
w.set_ainsel(ch.channel());
w.set_err_sticky(true); // clear previous errors
w.set_start_many(false);
});
// wait for previous conversions and drain fifo. an earlier batch read may have
// been cancelled, leaving the adc running.
while !r.cs().read().ready() {}
while !r.fcs().read().empty() {
r.fifo().read();
}
// set up fifo for dma
r.fcs().write(|w| {
w.set_thresh(1);
w.set_dreq_en(true);
w.set_shift(mem::size_of::<W>() == 1);
w.set_en(true);
w.set_err(fcs_err);
});
// reset dma config on drop, regardless of whether it was a future being cancelled
// or the method returning normally.
struct ResetDmaConfig;
impl Drop for ResetDmaConfig {
fn drop(&mut self) {
pac::ADC.cs().write_clear(|w| w.set_start_many(true));
while !pac::ADC.cs().read().ready() {}
pac::ADC.fcs().write_clear(|w| {
w.set_dreq_en(true);
w.set_shift(true);
w.set_en(true);
});
}
}
let auto_reset = ResetDmaConfig;
let dma = unsafe { dma::read(dma, r.fifo().as_ptr() as *const W, buf as *mut [W], 36) };
// start conversions and wait for dma to finish. we can't report errors early
// because there's no interrupt to signal them, and inspecting every element
// of the fifo is too costly to do here.
r.div().write_set(|w| w.set_int(div));
r.cs().write_set(|w| w.set_start_many(true));
dma.await;
mem::drop(auto_reset);
// we can't report errors before the conversions have ended since no interrupt
// exists to report them early, and since they're exceedingly rare we probably don't
// want to anyway.
match r.cs().read().err_sticky() {
false => Ok(()),
true => Err(Error::ConversionFailed),
}
}
/// Sample multiple values from a channel using DMA.
#[inline]
pub async fn read_many<S: AdcSample>(
&mut self,
ch: &mut Channel<'_>,
buf: &mut [S],
div: u16,
dma: impl Peripheral<P = impl dma::Channel>,
) -> Result<(), Error> {
self.read_many_inner(ch, buf, false, div, dma).await
}
/// Sample multiple values from a channel using DMA with errors inlined in samples.
#[inline]
pub async fn read_many_raw(
&mut self,
ch: &mut Channel<'_>,
buf: &mut [Sample],
div: u16,
dma: impl Peripheral<P = impl dma::Channel>,
) {
// errors are reported in individual samples
let _ = self
.read_many_inner(ch, unsafe { mem::transmute::<_, &mut [u16]>(buf) }, true, div, dma)
.await;
}
}
impl<'d> Adc<'d, Blocking> {
/// Create ADC driver in blocking mode.
pub fn new_blocking(_inner: impl Peripheral<P = ADC> + 'd, _config: Config) -> Self {
Self::setup();
Self { phantom: PhantomData }
}
}
/// Interrupt handler.
pub struct InterruptHandler {
_empty: (),
}
impl interrupt::typelevel::Handler<interrupt::typelevel::ADC_IRQ_FIFO> for InterruptHandler {
unsafe fn on_interrupt() {
let r = Adc::<Async>::regs();
r.inte().write(|w| w.set_fifo(false));
WAKER.wake();
}
}
trait SealedAdcSample: crate::dma::Word {}
trait SealedAdcChannel {}
/// ADC sample.
#[allow(private_bounds)]
pub trait AdcSample: SealedAdcSample {}
impl SealedAdcSample for u16 {}
impl AdcSample for u16 {}
impl SealedAdcSample for u8 {}
impl AdcSample for u8 {}
/// ADC channel.
#[allow(private_bounds)]
pub trait AdcChannel: SealedAdcChannel {}
/// ADC pin.
pub trait AdcPin: AdcChannel + gpio::Pin {}
macro_rules! impl_pin {
($pin:ident, $channel:expr) => {
impl SealedAdcChannel for peripherals::$pin {}
impl AdcChannel for peripherals::$pin {}
impl AdcPin for peripherals::$pin {}
};
}
impl_pin!(PIN_26, 0);
impl_pin!(PIN_27, 1);
impl_pin!(PIN_28, 2);
impl_pin!(PIN_29, 3);
impl SealedAdcChannel for peripherals::ADC_TEMP_SENSOR {}
impl AdcChannel for peripherals::ADC_TEMP_SENSOR {}