Rename DelayUs to DelayNs, add delay_ns.

Author: Dirbaio

embedded-hal-async/CHANGELOG.md

@@ -9,6 +9,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Minor document fixes.
 - Add #[inline] hints to most of `embedded-hal-async` functions.
+- delay: Rename `DelayUs` to `DelayNs`
+- delay: Add `DelayNs::delay_ns()`
+- delay: Add default impls of `delay_ms` and `delay_us` based on `delay_ns`.
 
 ## [v1.0.0-rc.1] - 2023-08-15
 

embedded-hal-async/src/delay.rs

@@ -1,20 +1,42 @@
 //! Delays.
 
-/// Microsecond delay.
-pub trait DelayUs {
+/// Delay with up to nanosecond precision.
+pub trait DelayNs {
+    /// Pauses execution for at minimum `ns` nanoseconds. Pause can be longer
+    /// if the implementation requires it due to precision/timing issues.
+    async fn delay_ns(&mut self, ns: u32);
+
     /// Pauses execution for at minimum `us` microseconds. Pause can be longer
     /// if the implementation requires it due to precision/timing issues.
-    async fn delay_us(&mut self, us: u32);
+    async fn delay_us(&mut self, mut us: u32) {
+        while us > 4_294_967 {
+            us -= 4_294_967;
+            self.delay_ns(4_294_967_000).await;
+        }
+        self.delay_ns(us * 1_000).await;
+    }
 
     /// Pauses execution for at minimum `ms` milliseconds. Pause can be longer
     /// if the implementation requires it due to precision/timing issues.
-    async fn delay_ms(&mut self, ms: u32);
+    #[inline]
+    async fn delay_ms(&mut self, mut ms: u32) {
+        while ms > 4294 {
+            ms -= 4294;
+            self.delay_ns(4_294_000_000).await;
+        }
+        self.delay_ns(ms * 1_000_000).await;
+    }
 }
 
-impl<T> DelayUs for &mut T
+impl<T> DelayNs for &mut T
 where
-    T: DelayUs + ?Sized,
+    T: DelayNs + ?Sized,
 {
+    #[inline]
+    async fn delay_ns(&mut self, ns: u32) {
+        T::delay_ns(self, ns).await;
+    }
+
     #[inline]
     async fn delay_us(&mut self, us: u32) {
         T::delay_us(self, us).await;

embedded-hal-bus/src/spi/critical_section.rs

@@ -1,6 +1,6 @@
 use core::cell::RefCell;
 use critical_section::Mutex;
-use embedded_hal::delay::DelayUs;
+use embedded_hal::delay::DelayNs;
 use embedded_hal::digital::OutputPin;
 use embedded_hal::spi::{ErrorType, Operation, SpiBus, SpiDevice};
 
@@ -60,7 +60,7 @@ impl<'a, Word: Copy + 'static, BUS, CS, D> SpiDevice<Word> for CriticalSectionDe
 where
     BUS: SpiBus<Word>,
     CS: OutputPin,
-    D: DelayUs,
+    D: DelayNs,
 {
     #[inline]
     fn transaction(&mut self, operations: &mut [Operation<'_, Word>]) -> Result<(), Self::Error> {

embedded-hal-bus/src/spi/exclusive.rs

@@ -1,11 +1,11 @@
 //! SPI bus sharing mechanisms.
 
-use embedded_hal::delay::DelayUs;
+use embedded_hal::delay::DelayNs;
 use embedded_hal::digital::OutputPin;
 use embedded_hal::spi::{ErrorType, Operation, SpiBus, SpiDevice};
 #[cfg(feature = "async")]
 use embedded_hal_async::{
-    delay::DelayUs as AsyncDelayUs,
+    delay::DelayNs as AsyncDelayUs,
     spi::{SpiBus as AsyncSpiBus, SpiDevice as AsyncSpiDevice},
 };
 
@@ -70,7 +70,7 @@ impl<Word: Copy + 'static, BUS, CS, D> SpiDevice<Word> for ExclusiveDevice<BUS,
 where
     BUS: SpiBus<Word>,
     CS: OutputPin,
-    D: DelayUs,
+    D: DelayNs,
 {
     #[inline]
     fn transaction(&mut self, operations: &mut [Operation<'_, Word>]) -> Result<(), Self::Error> {

embedded-hal-bus/src/spi/mod.rs

@@ -53,23 +53,18 @@ fn no_delay_panic() {
     panic!("You've tried to execute a SPI transaction containing a `Operation::Delay` in a `SpiDevice` created with `new_no_delay()`. Create it with `new()` instead, passing a `DelayUs` implementation.");
 }
 
-impl embedded_hal::delay::DelayUs for NoDelay {
+impl embedded_hal::delay::DelayNs for NoDelay {
     #[inline]
-    fn delay_us(&mut self, _us: u32) {
+    fn delay_ns(&mut self, _ns: u32) {
         no_delay_panic();
     }
 }
 
 #[cfg(feature = "async")]
 #[cfg_attr(docsrs, doc(cfg(feature = "async")))]
-impl embedded_hal_async::delay::DelayUs for NoDelay {
+impl embedded_hal_async::delay::DelayNs for NoDelay {
     #[inline]
-    async fn delay_us(&mut self, _us: u32) {
-        no_delay_panic();
-    }
-
-    #[inline]
-    async fn delay_ms(&mut self, _ms: u32) {
+    async fn delay_ns(&mut self, _ns: u32) {
         no_delay_panic();
     }
 }

embedded-hal-bus/src/spi/mutex.rs

@@ -1,4 +1,4 @@
-use embedded_hal::delay::DelayUs;
+use embedded_hal::delay::DelayNs;
 use embedded_hal::digital::OutputPin;
 use embedded_hal::spi::{ErrorType, Operation, SpiBus, SpiDevice};
 use std::sync::Mutex;
@@ -58,7 +58,7 @@ impl<'a, Word: Copy + 'static, BUS, CS, D> SpiDevice<Word> for MutexDevice<'a, B
 where
     BUS: SpiBus<Word>,
     CS: OutputPin,
-    D: DelayUs,
+    D: DelayNs,
 {
     #[inline]
     fn transaction(&mut self, operations: &mut [Operation<'_, Word>]) -> Result<(), Self::Error> {

embedded-hal-bus/src/spi/refcell.rs

@@ -1,5 +1,5 @@
 use core::cell::RefCell;
-use embedded_hal::delay::DelayUs;
+use embedded_hal::delay::DelayNs;
 use embedded_hal::digital::OutputPin;
 use embedded_hal::spi::{ErrorType, Operation, SpiBus, SpiDevice};
 
@@ -57,7 +57,7 @@ impl<'a, Word: Copy + 'static, BUS, CS, D> SpiDevice<Word> for RefCellDevice<'a,
 where
     BUS: SpiBus<Word>,
     CS: OutputPin,
-    D: DelayUs,
+    D: DelayNs,
 {
     #[inline]
     fn transaction(&mut self, operations: &mut [Operation<'_, Word>]) -> Result<(), Self::Error> {

embedded-hal-bus/src/spi/shared.rs

@@ -1,4 +1,4 @@
-use embedded_hal::delay::DelayUs;
+use embedded_hal::delay::DelayNs;
 use embedded_hal::digital::OutputPin;
 use embedded_hal::spi::{ErrorType, Operation, SpiBus};
 
@@ -15,7 +15,7 @@ pub fn transaction<Word, BUS, CS, D>(
 where
     BUS: SpiBus<Word> + ErrorType,
     CS: OutputPin,
-    D: DelayUs,
+    D: DelayNs,
     Word: Copy,
 {
     cs.set_low().map_err(DeviceError::Cs)?;

embedded-hal/CHANGELOG.md

@@ -10,6 +10,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Minor document fixes.
 - Add #[inline] hints to most of `embedded-hal` functions.
 - pwm: rename `get_max_duty_cycle` to `max_duty_cycle`.
+- delay: Rename `DelayUs` to `DelayNs`
+- delay: Add `DelayNs::delay_ns()`
+- delay: Add default impls of `delay_ms` and `delay_us` based on `delay_ns`.
+- delay: Make the default impl of `delay_ms` more efficient, it now does less calls to the underlying `delay_ns` (previously `delay_us`).
 
 ## [v1.0.0-rc.1] - 2023-08-15
 

embedded-hal/src/delay.rs

@@ -1,25 +1,42 @@
 //! Delays.
 
-/// Microsecond delay.
-pub trait DelayUs {
+/// Delay with up to nanosecond precision.
+pub trait DelayNs {
+    /// Pauses execution for at minimum `ns` nanoseconds. Pause can be longer
+    /// if the implementation requires it due to precision/timing issues.
+    fn delay_ns(&mut self, ns: u32);
+
     /// Pauses execution for at minimum `us` microseconds. Pause can be longer
     /// if the implementation requires it due to precision/timing issues.
-    fn delay_us(&mut self, us: u32);
+    fn delay_us(&mut self, mut us: u32) {
+        while us > 4_294_967 {
+            us -= 4_294_967;
+            self.delay_ns(4_294_967_000);
+        }
+        self.delay_ns(us * 1_000);
+    }
 
     /// Pauses execution for at minimum `ms` milliseconds. Pause can be longer
     /// if the implementation requires it due to precision/timing issues.
     #[inline]
-    fn delay_ms(&mut self, ms: u32) {
-        for _ in 0..ms {
-            self.delay_us(1000);
+    fn delay_ms(&mut self, mut ms: u32) {
+        while ms > 4294 {
+            ms -= 4294;
+            self.delay_ns(4_294_000_000);
         }
+        self.delay_ns(ms * 1_000_000);
     }
 }
 
-impl<T> DelayUs for &mut T
+impl<T> DelayNs for &mut T
 where
-    T: DelayUs + ?Sized,
+    T: DelayNs + ?Sized,
 {
+    #[inline]
+    fn delay_ns(&mut self, ns: u32) {
+        T::delay_ns(self, ns);
+    }
+
     #[inline]
     fn delay_us(&mut self, us: u32) {
         T::delay_us(self, us);