From 23d83bac3e26b5301bc54227a4bc2249150e43a8 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Thu, 22 Jun 2017 15:56:14 -0500
Subject: [PATCH] ADC + DMA API
---
Cargo.toml | 1 +
src/adc.rs | 149 +++++++++++++++++++++++++++++++++++++++++++++++++++++
src/dma.rs | 126 +++++++++++++++++++++++++++++++++++++++++++-
src/lib.rs | 2 +
src/pwm.rs | 2 +-
5 files changed, 277 insertions(+), 3 deletions(-)
create mode 100644 src/adc.rs
diff --git a/Cargo.toml b/Cargo.toml
index 9f5555b..b959bb8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,6 +11,7 @@ version = "0.1.0"
[dependencies]
static-ref = "0.1.0"
stm32f103xx = "0.6.1"
+volatile-register = "0.2.0"
[dependencies.cast]
default-features = false
diff --git a/src/adc.rs b/src/adc.rs
new file mode 100644
index 0000000..0e16b65
--- /dev/null
+++ b/src/adc.rs
@@ -0,0 +1,149 @@
+//! Analog to Digital Converter
+
+use core::marker::Unsize;
+
+use cast::u16;
+use hal::prelude::*;
+use static_ref::Ref;
+
+use dma::{self, CircBuffer, Dma1Channel1};
+use stm32f103xx::{ADC1, DMA1, GPIOA, RCC, TIM2};
+use {Channel, Pwm};
+
+/// ADC Channel 1 (PA1)
+pub struct Adc1<'a>(pub &'a ADC1);
+
+impl<'a> Adc1<'a> {
+ /// Initializes the ADC
+ ///
+ /// NOTE `Pwm<TIM2>.init` must be called before this method because both
+ /// methods configure the PA1 pin (one as input and the other as output :-/)
+ pub fn init(&self, dma1: &DMA1, gpioa: &GPIOA, rcc: &RCC) {
+ let adc1 = self.0;
+
+ // enable ADC1, DMA1, GPIOA, TIM2
+ rcc.ahbenr.modify(|_, w| w.dma1en().enabled());
+ rcc.apb1enr.modify(|_, w| w.tim2en().enabled());
+ rcc.apb2enr
+ .modify(|_, w| w.adc1en().enabled().iopaen().enabled());
+
+ // Set PA1 as analog input
+ gpioa.crl.modify(|_, w| w.cnf1().bits(0b00).mode1().input());
+
+ // Sample only the channel 1
+ adc1.sqr1.modify(|_, w| unsafe { w.l().bits(1) });
+ adc1.sqr3.modify(|_, w| unsafe { w.sq1().bits(1) });
+
+ // Sample time: 55.5 + 12.5 = 68 cycles
+ adc1.smpr2.modify(|_, w| unsafe { w.smp1().bits(0b101) });
+
+ // ADC1
+ // mem2mem: Memory to memory mode disabled
+ // pl: Medium priority
+ // msize: Memory size = 16 bits
+ // psize: Peripheral size = 16 bits
+ // minc: Memory increment mode enabled
+ // pinc: Peripheral increment mode disabled
+ // circ: Circular mode enabled
+ // dir: Transfer from peripheral to memory
+ // htie: Half transfer interrupt enabled
+ // tceie: Transfer complete interrupt enabled
+ // en: Disabled
+ dma1.ccr1.write(|w| unsafe {
+ w.mem2mem()
+ .clear()
+ .pl()
+ .bits(0b01)
+ .msize()
+ .bits(0b01)
+ .psize()
+ .bits(0b01)
+ .minc()
+ .set()
+ .pinc()
+ .clear()
+ .circ()
+ .set()
+ .dir()
+ .clear()
+ .htie()
+ .set()
+ .tcie()
+ .set()
+ .en()
+ .clear()
+ });
+
+ // exttrig: Conversion on external event enabled
+ // extsel: Timer 2 CC2 event
+ // align: Right alignment
+ // dma: DMA mode enabled
+ // cont: Single conversion mode
+ // adon: Disable ADC conversion
+ adc1.cr2.write(|w| unsafe {
+ w.exttrig()
+ .set()
+ .extsel()
+ .bits(0b011) // T2C2
+ // .bits(0b111) // swstart
+ .align()
+ .clear()
+ .dma()
+ .set()
+ .cont()
+ .clear()
+ .adon()
+ .clear()
+ });
+ }
+
+ /// Disables the ADC
+ pub fn disable(&self) {
+ self.0.cr2.modify(|_, w| w.adon().clear());
+ }
+
+ /// Enables the ADC
+ pub fn enable(&self) {
+ self.0.cr2.modify(|_, w| w.adon().set());
+ }
+
+ /// Starts an analog to digital conversion that will be periodically
+ /// triggered by the channel 2 of TIM2
+ ///
+ /// The conversions will be stored in the circular `buffer`
+ pub fn start<B>(
+ &self,
+ buffer: Ref<CircBuffer<u16, B, Dma1Channel1>>,
+ dma1: &DMA1,
+ pwm: Pwm<TIM2>,
+ ) -> Result<(), dma::Error>
+ where
+ B: Unsize<[u16]>,
+ {
+ let adc1 = self.0;
+
+
+ if dma1.ccr1.read().en().is_set() {
+ return Err(dma::Error::InUse);
+ }
+
+ pwm.disable(Channel::_2);
+ pwm.set_duty(Channel::_2, 1);
+
+ let buffer: &[u16] = &buffer.lock()[0];
+
+ dma1.cndtr1
+ .write(|w| unsafe { w.ndt().bits(u16(buffer.len() * 2).unwrap()) });
+
+ dma1.cpar1
+ .write(|w| unsafe { w.bits(&adc1.dr as *const _ as u32) });
+
+ dma1.cmar1
+ .write(|w| unsafe { w.bits(buffer.as_ptr() as u32) });
+
+ dma1.ccr1.modify(|_, w| w.en().set());
+ pwm.enable(Channel::_2);
+
+ Ok(())
+ }
+}
diff --git a/src/dma.rs b/src/dma.rs
index c47fbcf..d4f6f31 100644
--- a/src/dma.rs
+++ b/src/dma.rs
@@ -1,21 +1,30 @@
//! Direct Memory Access (DMA)
use core::cell::{Cell, UnsafeCell};
-use core::marker::PhantomData;
-use core::ops;
+use core::marker::{PhantomData, Unsize};
+use core::{ops, slice};
use nb;
use stm32f103xx::DMA1;
+use volatile_register::RO;
/// DMA error
#[derive(Debug)]
pub enum Error {
/// DMA channel in use
InUse,
+ /// Previous data got overwritten before it could be read because it was
+ /// not accessed in a timely fashion
+ Overrun,
/// Transfer error
Transfer,
}
+/// Channel 1 of DMA1
+pub struct Dma1Channel1 {
+ _0: (),
+}
+
/// Channel 2 of DMA1
pub struct Dma1Channel2 {
_0: (),
@@ -249,3 +258,116 @@ impl<T> Buffer<T, Dma1Channel5> {
}
}
}
+
+/// A circular buffer associated to a DMA `CHANNEL`
+pub struct CircBuffer<T, B, CHANNEL>
+where
+ B: Unsize<[T]>,
+{
+ _marker: PhantomData<CHANNEL>,
+ _t: PhantomData<[T]>,
+ buffer: UnsafeCell<[B; 2]>,
+ status: Cell<CircStatus>,
+}
+
+impl<T, B, CHANNEL> CircBuffer<T, B, CHANNEL>
+where
+ B: Unsize<[T]>,
+{
+ pub(crate) fn lock(&self) -> &[B; 2] {
+ assert_eq!(self.status.get(), CircStatus::Free);
+
+ self.status.set(CircStatus::MutatingFirstHalf);
+
+ unsafe { &*self.buffer.get() }
+ }
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+enum CircStatus {
+ /// Not in use by the DMA
+ Free,
+ /// The DMA is mutating the first half of the buffer
+ MutatingFirstHalf,
+ /// The DMA is mutating the second half of the buffer
+ MutatingSecondHalf,
+}
+
+impl<T, B> CircBuffer<T, B, Dma1Channel1>
+where
+ B: Unsize<[T]>,
+ T: Atomic,
+{
+ /// Constructs a circular buffer from two halves
+ pub const fn new(buffer: [B; 2]) -> Self {
+ CircBuffer {
+ _t: PhantomData,
+ _marker: PhantomData,
+ buffer: UnsafeCell::new(buffer),
+ status: Cell::new(CircStatus::Free),
+ }
+ }
+
+ /// Yields read access to the half of the circular buffer that's not
+ /// currently being mutated by the DMA
+ pub fn read(&self, dma1: &DMA1) -> nb::Result<&[RO<T>], Error> {
+ let status = self.status.get();
+
+ assert_ne!(status, CircStatus::Free);
+
+ let isr = dma1.isr.read();
+
+ if isr.teif1().is_set() {
+ Err(nb::Error::Other(Error::Transfer))
+ } else {
+ match status {
+ CircStatus::MutatingFirstHalf => {
+ if isr.tcif1().is_set() {
+ Err(nb::Error::Other(Error::Overrun))
+ } else if isr.htif1().is_set() {
+ dma1.ifcr.write(|w| w.chtif1().set());
+
+ self.status.set(CircStatus::MutatingSecondHalf);
+
+ unsafe {
+ let half: &[T] = &(*self.buffer.get())[0];
+ Ok(slice::from_raw_parts(
+ half.as_ptr() as *const _,
+ half.len(),
+ ))
+ }
+ } else {
+ Err(nb::Error::WouldBlock)
+ }
+ }
+ CircStatus::MutatingSecondHalf => {
+ if isr.htif1().is_set() {
+ Err(nb::Error::Other(Error::Overrun))
+ } else if isr.tcif1().is_set() {
+ dma1.ifcr.write(|w| w.ctcif1().set());
+
+ self.status.set(CircStatus::MutatingFirstHalf);
+
+ unsafe {
+ let half: &[T] = &(*self.buffer.get())[1];
+ Ok(slice::from_raw_parts(
+ half.as_ptr() as *const _,
+ half.len(),
+ ))
+ }
+ } else {
+ Err(nb::Error::WouldBlock)
+ }
+ }
+ _ => unreachable!(),
+ }
+ }
+ }
+}
+
+/// Values that can be atomically read
+pub trait Atomic: Copy {}
+
+impl Atomic for u8 {}
+impl Atomic for u16 {}
+impl Atomic for u32 {}
diff --git a/src/lib.rs b/src/lib.rs
index ccf869a..fd8c0a7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -23,9 +23,11 @@ extern crate either;
extern crate embedded_hal as hal;
extern crate nb;
extern crate static_ref;
+extern crate volatile_register;
pub extern crate stm32f103xx;
+pub mod adc;
pub mod capture;
pub mod dma;
pub mod gpio;
diff --git a/src/pwm.rs b/src/pwm.rs
index e9cdcc0..4d48d7e 100644
--- a/src/pwm.rs
+++ b/src/pwm.rs
@@ -392,7 +392,7 @@ where
// pinc: Peripheral increment mode disabled
// circ: Circular mode disabled
// dir: Transfer from memory to peripheral
- // tceie: Transfer complete interrupt disabled
+ // tceie: Transfer complete interrupt enabled
// en: Disabled
dma1.ccr2.write(|w| unsafe {
w.mem2mem()
--
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