add embassy sync channel example for message passing between interrupt and task

embassy-sync/src/channel.rs

@@ -17,6 +17,31 @@
 //! messages that it can store, and if this limit is reached, trying to send
 //! another message will result in an error being returned.
 //!
+//! # Example: Message passing between task and interrupt handler
+//!
+//! ```rust
+//! use embassy_sync::channel::Channel;
+//! use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
+//!
+//! static SHARED_CHANNEL: Channel<CriticalSectionRawMutex, u32, 8> = Channel::new();
+//!
+//! fn my_interrupt_handler() {
+//!     // Do some work..
+//!     // ...
+//!     if let Err(e) = SHARED_CHANNEL.sender().try_send(42) {
+//!         // Channel is full..
+//!     }
+//! }
+//!
+//! async fn my_async_task() {
+//!     // ...
+//!     let receiver = SHARED_CHANNEL.receiver();
+//!     loop {
+//!         let data_from_interrupt = receiver.receive().await;
+//!         // Do something with the data.
+//!     }
+//! }
+//! ```
 
 use core::cell::RefCell;
 use core::future::Future;