Add src/timer/monotonics.rs from f4xx-hal

Co-authored-by: Henrik Snöman <henrik.snoman@dectron.se>

Author: usbalbin

.vscode/settings.json

@@ -3,6 +3,7 @@
   "rust-analyzer.cargo.target": "thumbv6m-none-eabi",
   "rust-analyzer.cargo.features": [
     "rt",
-    "stm32g081"
+    "stm32g081",
+    "rtic2"
   ]
 }

Cargo.toml

@@ -23,6 +23,10 @@ fugit = "0.3.7"
 embedded-hal = "1.0.0"
 bare-metal = "1.0.0"
 portable-atomic = { version = "1.10.0", features = ["critical-section"] }
+embedded-hal-async = { version = "1.0.0", optional = true }
+atomic-polyfill = { version = "1.0.3", optional = true }
+rtic-time = { version = "2.0.0", optional = true }
+embedded-time = { version = "0.12.1", optional = true }
 
 [dependencies.stm32g0]
 package = "stm32g0-staging"
@@ -61,6 +65,7 @@ stm32g0x1 = []
 
 i2c-blocking = []
 i2c-nonblocking = []
+rtic2 = ["dep:embedded-hal-async", "dep:atomic-polyfill", "dep:rtic-time"]
 
 [profile.dev]
 incremental = false

src/timer/mod.rs

@@ -4,9 +4,12 @@ use crate::stm32::*;
 use crate::time::{Hertz, MicroSecond};
 use core::marker::PhantomData;
 use fugit::HertzU32;
+use fugit::RateExtU32;
 use void::Void;
 
 pub mod delay;
+#[cfg(feature = "rtic2")]
+pub mod monotonics;
 pub mod opm;
 pub mod pins;
 pub mod pwm;
@@ -30,6 +33,46 @@ type Channel2 = Channel<1>;
 type Channel3 = Channel<2>;
 type Channel4 = Channel<3>;
 
+/// Timer wrapper for fixed precision timers.
+///
+/// Uses `fugit::TimerDurationU32` for most of operations
+pub struct FTimer<TIM, const FREQ: u32> {
+    tim: TIM,
+}
+
+/// `FTimer` with precision of 1 μs (1 MHz sampling)
+pub type FTimerUs<TIM> = FTimer<TIM, 1_000_000>;
+
+/// `FTimer` with precision of 1 ms (1 kHz sampling)
+///
+/// NOTE: don't use this if your system frequency more than 65 MHz
+pub type FTimerMs<TIM> = FTimer<TIM, 1_000>;
+
+impl<TIM: private::TimerBase, const FREQ: u32> FTimer<TIM, FREQ> {
+    /// Initialize timer
+    pub fn new(mut tim: TIM, rcc: &mut Rcc) -> Self {
+        tim.init(rcc);
+        tim.set_freq(FREQ.Hz(), rcc.clocks.apb_tim_clk);
+
+        Self { tim }
+    }
+
+    /*/// Creates `Counter` that implements [embedded_hal_02::timer::CountDown]
+    pub fn counter(self) -> Counter<TIM, FREQ> {
+        Counter(self)
+    }
+
+    /// Creates `Delay` that implements [embedded_hal_02::blocking::delay] traits
+    pub fn delay(self) -> Delay<TIM, FREQ> {
+        Delay(self)
+    }*/
+
+    /// Releases the TIM peripheral
+    pub fn release(self) -> TIM {
+        self.tim
+    }
+}
+
 pub struct TimerFrequencySettings {
     psc: u16,
     arr: u32,
@@ -59,6 +102,8 @@ pub(super) mod private {
     use super::{Rcc, TimerFrequencySettings};
 
     pub trait TimerCommon {
+        type Width: Into<u32> + From<u16>;
+
         fn init(&mut self, rcc: &mut Rcc);
 
         fn set_urs(&mut self);
@@ -80,6 +125,8 @@ pub(super) mod private {
     }
 
     impl TimerCommon for SYST {
+        type Width = u32;
+
         fn init(&mut self, _rcc: &mut Rcc) {
             self.set_clock_source(SystClkSource::Core);
         }
@@ -144,6 +191,8 @@ macro_rules! timers {
     ($($TIM:ident: ($tim:ident, $cnt:ident $(,$cnt_h:ident)*),)+) => {
         $(
             impl private::TimerCommon for $TIM {
+                type Width = u16; // TODO: Are there any with 32 bits?
+
                 fn init(&mut self, rcc: &mut Rcc) {
                     $TIM::enable(rcc);
                     $TIM::reset(rcc);