From 53645d9d38bcb5904f1deba2cfa4e6719da2bc58 Mon Sep 17 00:00:00 2001
From: Richard Dodd <richard.o.dodd@gmail.com>
Date: Wed, 24 Mar 2021 18:33:17 +0100
Subject: [PATCH] nrf/saadc: initial implementation
---
embassy-nrf/src/lib.rs | 4 +
embassy-nrf/src/saadc.rs | 242 +++++++++++++++++++++++++++++++++++++++
2 files changed, 246 insertions(+)
create mode 100644 embassy-nrf/src/saadc.rs
diff --git a/embassy-nrf/src/lib.rs b/embassy-nrf/src/lib.rs
index 22c71e7f5..009cb99be 100644
--- a/embassy-nrf/src/lib.rs
+++ b/embassy-nrf/src/lib.rs
@@ -100,6 +100,7 @@ pub mod interrupt;
#[cfg(feature = "52840")]
pub mod qspi;
pub mod rtc;
+pub mod saadc;
pub mod spim;
pub mod uarte;
@@ -130,6 +131,9 @@ embassy_extras::peripherals! {
#[cfg(any(feature = "52833", feature = "52840"))]
spim3: SPIM3,
+ // SAADC
+ saadc: SAADC,
+
// GPIOTE
gpiote: GPIOTE,
gpiote_ch_0: GPIOTE_CH0,
diff --git a/embassy-nrf/src/saadc.rs b/embassy-nrf/src/saadc.rs
new file mode 100644
index 000000000..b854ce780
--- /dev/null
+++ b/embassy-nrf/src/saadc.rs
@@ -0,0 +1,242 @@
+use core::future::Future;
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::sync::atomic::{compiler_fence, Ordering};
+use core::task::Poll;
+use embassy::traits;
+use embassy::util::{wake_on_interrupt, PeripheralBorrow};
+use embassy_extras::unborrow;
+use futures::future::poll_fn;
+use traits::spi::FullDuplex;
+
+use crate::gpio::Pin as GpioPin;
+use crate::interrupt::{self, Interrupt};
+use crate::{pac, peripherals, slice_in_ram_or};
+
+#[cfg(feature = "9160")]
+use pac::{saadc_ns as saadc, SAADC_NS as SAADC};
+
+#[cfg(not(feature = "9160"))]
+use pac::{saadc, SAADC};
+
+pub use saadc::{
+ ch::{
+ config::{GAIN_A as Gain, REFSEL_A as Reference, RESP_A as Resistor, TACQ_A as Time},
+ pselp::PSELP_A as PositiveChannel,
+ },
+ oversample::OVERSAMPLE_A as Oversample,
+ resolution::VAL_A as Resolution,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[non_exhaustive]
+pub enum Error {}
+
+/// One-shot saadc. Continuous sample mode TODO.
+pub struct OneShot<'d, T: PositivePin> {
+ peri: peripherals::SAADC,
+ positive_pin: T,
+ irq: interrupt::SAADC,
+ phantom: PhantomData<(&'d mut peripherals::SAADC, &'d mut T)>,
+}
+
+/// Used to configure the SAADC peripheral.
+///
+/// See the `Default` impl for suitable default values.
+pub struct Config {
+ /// Output resolution in bits.
+ pub resolution: Resolution,
+ /// Average 2^`oversample` input samples before transferring the result into memory.
+ pub oversample: Oversample,
+ /// Reference voltage of the SAADC input.
+ pub reference: Reference,
+ /// Gain used to control the effective input range of the SAADC.
+ pub gain: Gain,
+ /// Positive channel resistor control.
+ pub resistor: Resistor,
+ /// Acquisition time in microseconds.
+ pub time: Time,
+}
+
+impl Default for Config {
+ fn default() -> Self {
+ Self {
+ resolution: Resolution::_14BIT,
+ oversample: Oversample::OVER8X,
+ reference: Reference::VDD1_4,
+ gain: Gain::GAIN1_4,
+ resistor: Resistor::BYPASS,
+ time: Time::_20US,
+ }
+ }
+}
+
+impl<'d, T: PositivePin> OneShot<'d, T> {
+ pub fn new(
+ saadc: impl PeripheralBorrow<Target = peripherals::SAADC> + 'd,
+ irq: impl PeripheralBorrow<Target = interrupt::SAADC> + 'd,
+ positive_pin: impl PeripheralBorrow<Target = T> + 'd,
+ config: Config,
+ ) -> Self {
+ unborrow!(saadc, irq, positive_pin);
+
+ let r = unsafe { &*SAADC::ptr() };
+
+ let Config {
+ resolution,
+ oversample,
+ reference,
+ gain,
+ resistor,
+ time,
+ } = config;
+
+ // Configure pins
+ r.enable.write(|w| w.enable().enabled());
+ r.resolution.write(|w| w.val().variant(resolution));
+ r.oversample.write(|w| w.oversample().variant(oversample));
+
+ r.ch[0].config.write(|w| {
+ w.refsel().variant(reference);
+ w.gain().variant(gain);
+ w.tacq().variant(time);
+ w.mode().se();
+ w.resp().variant(resistor);
+ w.resn().bypass();
+ if !matches!(oversample, Oversample::BYPASS) {
+ w.burst().enabled();
+ } else {
+ w.burst().disabled();
+ }
+ w
+ });
+
+ // Set positive channel
+ r.ch[0]
+ .pselp
+ .write(|w| w.pselp().variant(positive_pin.channel()));
+
+ // Disable all events interrupts
+ r.intenclr.write(|w| unsafe { w.bits(0x003F_FFFF) });
+
+ Self {
+ peri: saadc,
+ positive_pin,
+ irq,
+ phantom: PhantomData,
+ }
+ }
+
+ fn regs(&self) -> &saadc::RegisterBlock {
+ unsafe { &*SAADC::ptr() }
+ }
+}
+
+impl<'d, T: PositivePin> Drop for OneShot<'d, T> {
+ fn drop(&mut self) {
+ let r = self.regs();
+ r.enable.write(|w| w.enable().disabled());
+ }
+}
+
+pub trait Sample {
+ type SampleFuture<'a>: Future<Output = i16> + 'a
+ where
+ Self: 'a;
+
+ fn sample<'a>(self: Pin<&'a mut Self>) -> Self::SampleFuture<'a>;
+}
+
+impl<'d, T: PositivePin> Sample for OneShot<'d, T> {
+ #[rustfmt::skip]
+ type SampleFuture<'a> where Self: 'a = impl Future<Output = i16> + 'a;
+
+ fn sample<'a>(self: Pin<&'a mut Self>) -> Self::SampleFuture<'a> {
+ async move {
+ let this = unsafe { self.get_unchecked_mut() };
+ let r = this.regs();
+
+ // Set up the DMA
+ let mut val: i16 = 0;
+ r.result
+ .ptr
+ .write(|w| unsafe { w.ptr().bits(((&mut val) as *mut _) as u32) });
+ r.result.maxcnt.write(|w| unsafe { w.maxcnt().bits(1) });
+
+ // Reset and enable the end event
+ r.events_end.reset();
+ r.intenset.write(|w| w.end().set());
+
+ // Don't reorder the ADC start event before the previous writes. Hopefully this
+ // wouldn't happen anyway.
+ compiler_fence(Ordering::SeqCst);
+
+ r.tasks_start.write(|w| unsafe { w.bits(1) });
+ r.tasks_sample.write(|w| unsafe { w.bits(1) });
+
+ // Wait for 'end' event.
+ poll_fn(|cx| {
+ let r = this.regs();
+
+ if r.events_end.read().bits() != 0 {
+ r.events_end.reset();
+ return Poll::Ready(());
+ }
+
+ wake_on_interrupt(&mut this.irq, cx.waker());
+
+ Poll::Pending
+ })
+ .await;
+
+ // The DMA wrote the sampled value to `val`.
+ val
+ }
+ }
+}
+
+/// A pin that can be used as the positive end of a ADC differential in the SAADC periperhal.
+///
+/// Currently negative is always shorted to ground (0V).
+pub trait PositivePin {
+ fn channel(&self) -> PositiveChannel;
+}
+
+macro_rules! positive_pin_mappings {
+ ( $($ch:ident => $pin:ident,)*) => {
+ $(
+ impl PositivePin for crate::peripherals::$pin {
+ fn channel(&self) -> PositiveChannel {
+ PositiveChannel::$ch
+ }
+ }
+ )*
+ };
+}
+
+// TODO the variant names are unchecked
+// the pins are copied from nrf hal
+#[cfg(feature = "9160")]
+positive_pin_mappings! {
+ ANALOGINPUT0 => P0_13,
+ ANALOGINPUT1 => P0_14,
+ ANALOGINPUT2 => P0_15,
+ ANALOGINPUT3 => P0_16,
+ ANALOGINPUT4 => P0_17,
+ ANALOGINPUT5 => P0_18,
+ ANALOGINPUT6 => P0_19,
+ ANALOGINPUT7 => P0_20,
+}
+
+#[cfg(not(feature = "9160"))]
+positive_pin_mappings! {
+ ANALOGINPUT0 => P0_02,
+ ANALOGINPUT1 => P0_03,
+ ANALOGINPUT2 => P0_04,
+ ANALOGINPUT3 => P0_05,
+ ANALOGINPUT4 => P0_28,
+ ANALOGINPUT5 => P0_29,
+ ANALOGINPUT6 => P0_30,
+ ANALOGINPUT7 => P0_31,
+}