Add async Delay implementation for tokio.

Author: reitermarkus

Cargo.toml

@@ -15,7 +15,7 @@ edition = "2018"
 [features]
 gpio_sysfs = ["sysfs_gpio"]
 gpio_cdev = ["gpio-cdev"]
-async-tokio = ["gpio-cdev/async-tokio"]
+async-tokio = ["gpio-cdev/async-tokio", "dep:embedded-hal-async", "tokio/time"]
 i2c = ["i2cdev"]
 spi = ["spidev"]
 
@@ -24,13 +24,15 @@ default = [ "gpio_cdev", "gpio_sysfs", "i2c", "spi" ]
 [dependencies]
 embedded-hal = "1"
 embedded-hal-nb = "1"
+embedded-hal-async = { version = "1", optional = true }
 gpio-cdev = { version = "0.6.0", optional = true }
 sysfs_gpio = { version = "0.6.1", optional = true }
 i2cdev = { version = "0.6.0", optional = true }
 nb = "1"
 serialport = { version = "4.2.0", default-features = false }
 spidev = { version = "0.6.0", optional = true }
 nix = "0.27.1"
+tokio = { version = "1", default-features = false, optional = true }
 
 [dev-dependencies]
 openpty = "0.2.0"

src/delay.rs

@@ -2,16 +2,23 @@
 //!
 //! [`embedded-hal`]: https://docs.rs/embedded-hal
 
-use cast::u64;
 use embedded_hal::delay::DelayNs;
 use std::thread;
 use std::time::Duration;
 
-/// Empty struct that provides delay functionality on top of `thread::sleep`
+/// Empty struct that provides delay functionality on top of `thread::sleep`,
+/// and `tokio::time::sleep` if the `async-tokio` feature is enabled.
 pub struct Delay;
 
 impl DelayNs for Delay {
     fn delay_ns(&mut self, n: u32) {
-        thread::sleep(Duration::from_nanos(u64(n)));
+        thread::sleep(Duration::from_nanos(n.into()));
+    }
+}
+
+#[cfg(feature = "async-tokio")]
+impl embedded_hal_async::delay::DelayNs for Delay {
+    async fn delay_ns(&mut self, n: u32) {
+        tokio::time::sleep(Duration::from_nanos(n.into())).await;
     }
 }