Add timer implementation

.travis.yml

@@ -15,4 +15,4 @@ matrix:
   fast_finish: true
 script:
   - rustup target add thumbv6m-none-eabi
-  - cargo build --features=$MCU
+  - cargo build --features=$MCU --examples --release

Cargo.toml

@@ -62,6 +62,22 @@ debug = true
 lto = true
 opt-level = "s"
 
+[[example]]
+name = "i2c_hal_ssd1306alphabeter"
+required-features = ["stm32f042"]
+
+[[example]]
+name = "i2c_hal_ina260serial"
+required-features = ["stm32f042"]
+
 [[example]]
 name = "led_hal_button_irq"
+required-features = ["stm32f042", "rt"]
+
+[[example]]
+name = "i2c_hal_ina260reader"
+required-features = ["stm32f042"]
+
+[[example]]
+name = "spi_hal_apa102c"
 required-features = ["stm32f042"]

examples/blinky_timer.rs

@@ -0,0 +1,40 @@
+#![no_main]
+#![no_std]
+
+use panic_halt;
+
+use stm32f0xx_hal as hal;
+
+use crate::hal::prelude::*;
+use crate::hal::stm32;
+use crate::hal::time::*;
+use crate::hal::timers::*;
+
+use cortex_m_rt::entry;
+use nb::block;
+
+#[entry]
+fn main() -> ! {
+    if let Some(p) = stm32::Peripherals::take() {
+        let gpioa = p.GPIOA.split();
+        /* (Re-)configure PA1 as output */
+        let mut led = gpioa.pa1.into_push_pull_output();
+
+        /* Constrain clocking registers */
+        let rcc = p.RCC.constrain();
+
+        /* Configure clock to 8 MHz (i.e. the default) and freeze it */
+        let clocks = rcc.cfgr.sysclk(8.mhz()).freeze();
+
+        let mut timer = Timer::tim1(p.TIM1, Hertz(1), clocks);
+
+        loop {
+            led.toggle();
+            block!(timer.wait()).ok();
+        }
+    }
+
+    loop {
+        continue;
+    }
+}

memory.x

@@ -1,8 +1,8 @@
 MEMORY
 {
   /* NOTE K = KiBi = 1024 bytes */
-  FLASH : ORIGIN = 0x08000000, LENGTH = 32K
-  RAM : ORIGIN = 0x20000000, LENGTH = 6K
+  FLASH : ORIGIN = 0x08000000, LENGTH = 16K
+  RAM : ORIGIN = 0x20000000, LENGTH = 4K
 }
 
 /* This is where the call stack will be allocated. */

src/lib.rs

@@ -17,3 +17,4 @@ pub mod rcc;
 pub mod serial;
 pub mod spi;
 pub mod time;
+pub mod timers;

src/timers.rs

@@ -0,0 +1,238 @@
+//! API for the integrated timers
+//!
+//! This only implements basic functions, a lot of things are missing
+//!
+//! # Example
+//! Blink the led with 1Hz
+//! ``` no_run
+//! use stm32f0xx_hal as hal;
+//!
+//! use crate::hal::stm32;
+//! use crate::hal::prelude::*;
+//! use crate::hal::time::*;
+//! use crate::hal::timers::*;
+//! use nb::block;
+//!
+//! let mut p = stm32::Peripherals::take().unwrap();
+//!
+//! let mut led = gpioa.pa1.into_push_pull_pull_output();
+//! let rcc = p.RCC.constrain().cfgr.freeze();
+//! let mut timer = Timer::tim1(p.TIM1, Hertz(1), clocks);
+//! loop {
+//!     led.toggle();
+//!     block!(timer.wait()).ok();
+//! }
+//! ```
+
+#[cfg(feature = "stm32f030")]
+use crate::stm32::{RCC, TIM1, TIM14, TIM15, TIM16, TIM17, TIM3, TIM6, TIM7};
+#[cfg(feature = "stm32f042")]
+use crate::stm32::{RCC, TIM1, TIM14, TIM16, TIM17, TIM2, TIM3};
+use cortex_m::peripheral::syst::SystClkSource;
+use cortex_m::peripheral::SYST;
+
+use crate::rcc::Clocks;
+use cast::{u16, u32};
+use embedded_hal::timer::{CountDown, Periodic};
+use nb;
+use void::Void;
+
+use crate::time::Hertz;
+
+/// Hardware timers
+pub struct Timer<TIM> {
+    clocks: Clocks,
+    tim: TIM,
+}
+
+/// Interrupt events
+pub enum Event {
+    /// Timer timed out / count down ended
+    TimeOut,
+}
+
+impl Timer<SYST> {
+    /// Configures the SYST clock as a periodic count down timer
+    pub fn syst<T>(mut syst: SYST, timeout: T, clocks: Clocks) -> Self
+    where
+        T: Into<Hertz>,
+    {
+        syst.set_clock_source(SystClkSource::Core);
+        let mut timer = Timer { tim: syst, clocks };
+        timer.start(timeout);
+        timer
+    }
+
+    /// Starts listening for an `event`
+    pub fn listen(&mut self, event: Event) {
+        match event {
+            Event::TimeOut => self.tim.enable_interrupt(),
+        }
+    }
+
+    /// Stops listening for an `event`
+    pub fn unlisten(&mut self, event: Event) {
+        match event {
+            Event::TimeOut => self.tim.disable_interrupt(),
+        }
+    }
+}
+
+impl CountDown for Timer<SYST> {
+    type Time = Hertz;
+
+    /// Start the timer with a `timeout`
+    fn start<T>(&mut self, timeout: T)
+    where
+        T: Into<Hertz>,
+    {
+        let rvr = self.clocks.sysclk().0 / timeout.into().0 - 1;
+
+        assert!(rvr < (1 << 24));
+
+        self.tim.set_reload(rvr);
+        self.tim.clear_current();
+        self.tim.enable_counter();
+    }
+
+    /// Return `Ok` if the timer has wrapped
+    /// Automatically clears the flag and restarts the time
+    fn wait(&mut self) -> nb::Result<(), Void> {
+        if self.tim.has_wrapped() {
+            Ok(())
+        } else {
+            Err(nb::Error::WouldBlock)
+        }
+    }
+}
+
+impl Periodic for Timer<SYST> {}
+
+macro_rules! timers {
+    ($($TIM:ident: ($tim:ident, $timXen:ident, $timXrst:ident, $apbenr:ident, $apbrstr:ident),)+) => {
+        $(
+            impl Timer<$TIM> {
+                // XXX(why not name this `new`?) bummer: constructors need to have different names
+                // even if the `$TIM` are non overlapping (compare to the `free` function below
+                // which just works)
+                /// Configures a TIM peripheral as a periodic count down timer
+                pub fn $tim<T>(tim: $TIM, timeout: T, clocks: Clocks) -> Self
+                where
+                    T: Into<Hertz>,
+                {
+                    // NOTE(unsafe) This executes only during initialisation
+                    let rcc = unsafe { &(*RCC::ptr()) };
+
+                    // enable and reset peripheral to a clean slate state
+                    rcc.$apbenr.modify(|_, w| w.$timXen().set_bit());
+                    rcc.$apbrstr.modify(|_, w| w.$timXrst().set_bit());
+                    rcc.$apbrstr.modify(|_, w| w.$timXrst().clear_bit());
+
+                    let mut timer = Timer {
+                        clocks,
+                        tim,
+                    };
+                    timer.start(timeout);
+
+                    timer
+                }
+
+                /// Starts listening for an `event`
+                pub fn listen(&mut self, event: Event) {
+                    match event {
+                        Event::TimeOut => {
+                            // Enable update event interrupt
+                            self.tim.dier.write(|w| w.uie().set_bit());
+                        }
+                    }
+                }
+
+                /// Stops listening for an `event`
+                pub fn unlisten(&mut self, event: Event) {
+                    match event {
+                        Event::TimeOut => {
+                            // Enable update event interrupt
+                            self.tim.dier.write(|w| w.uie().clear_bit());
+                        }
+                    }
+                }
+
+                /// Releases the TIM peripheral
+                pub fn release(self) -> $TIM {
+                    use crate::stm32::RCC;
+                    let rcc = unsafe { &(*RCC::ptr()) };
+                    // Pause counter
+                    self.tim.cr1.modify(|_, w| w.cen().clear_bit());
+                    // Disable timer
+                    rcc.$apbenr.modify(|_, w| w.$timXen().clear_bit());
+                    self.tim
+                }
+            }
+
+            impl CountDown for Timer<$TIM> {
+                type Time = Hertz;
+
+                /// Start the timer with a `timeout`
+                fn start<T>(&mut self, timeout: T)
+                where
+                    T: Into<Hertz>,
+                {
+                    // pause
+                    self.tim.cr1.modify(|_, w| w.cen().clear_bit());
+                    // restart counter
+                    self.tim.cnt.reset();
+
+                    let frequency = timeout.into().0;
+                    let ticks = self.clocks.pclk().0 / frequency;
+
+                    let psc = u16((ticks - 1) / (1 << 16)).unwrap();
+                    self.tim.psc.write(|w| unsafe { w.psc().bits(psc) });
+
+                    let arr = u16(ticks / u32(psc + 1)).unwrap();
+                    self.tim.arr.write(|w| unsafe { w.bits(u32(arr)) });
+
+                    // start counter
+                    self.tim.cr1.modify(|_, w| w.cen().set_bit());
+                }
+
+                /// Return `Ok` if the timer has wrapped
+                /// Automatically clears the flag and restarts the time
+                fn wait(&mut self) -> nb::Result<(), Void> {
+                    if self.tim.sr.read().uif().bit_is_clear() {
+                        Err(nb::Error::WouldBlock)
+                    } else {
+                        self.tim.sr.modify(|_, w| w.uif().clear_bit());
+                        Ok(())
+                    }
+                }
+            }
+
+            impl Periodic for Timer<$TIM> {}
+        )+
+    }
+}
+
+#[cfg(any(feature = "stm32f030", feature = "stm32f042",))]
+timers! {
+    TIM1: (tim1, tim1en, tim1rst, apb2enr, apb2rstr),
+    TIM3: (tim3, tim3en, tim3rst, apb1enr, apb1rstr),
+    TIM14: (tim14, tim14en, tim14rst, apb1enr, apb1rstr),
+    TIM16: (tim16, tim16en, tim16rst, apb2enr, apb2rstr),
+    TIM17: (tim17, tim17en, tim17rst, apb2enr, apb2rstr),
+}
+
+#[cfg(any(feature = "stm32f030x8", feature = "stm32f030xc"))]
+timers! {
+    TIM6: (tim6, tim6en, tim6rst, apb1enr, apb1rstr),
+    TIM15: (tim15, tim15en, tim15rst, apb2enr, apb2rstr),
+}
+
+#[cfg(feature = "stm32f030xc")]
+timers! {
+    TIM7: (tim7, tim7en, tim7rst, apb1enr, apb1rstr),
+}
+
+#[cfg(feature = "stm32f042")]
+timers! {
+    TIM2: (tim2, tim2en, tim2rst, apb1enr, apb1rstr),
+}