Fix #699

2 files changed, 17 insertions, 6 deletions

diff --git a/book/en/src/by-example/channel.md b/book/en/src/by-example/channel.md
index c020870..50c3278 100644
--- a/book/en/src/by-example/channel.md
+++ b/book/en/src/by-example/channel.md
@@ -1,6 +1,6 @@
 # Communication over channels.
 
-Channels can be used to communicate data between running *software* tasks. The channel is essentially a wait queue, allowing tasks with multiple producers and a single receiver. A channel is constructed in the `init` task and backed by statically allocated memory. Send and receive endpoints are distributed to *software* tasks:
+Channels can be used to communicate data between running tasks. The channel is essentially a wait queue, allowing tasks with multiple producers and a single receiver. A channel is constructed in the `init` task and backed by statically allocated memory. Send and receive endpoints are distributed to *software* tasks:
 
 ``` rust
 ...
@@ -16,6 +16,8 @@ const CAPACITY: usize = 5;
 
 In this case the channel holds data of `u32` type with a capacity of 5  elements. 
 
+Channels can also be used from *hardware* tasks, but only in a non-`async` manner using the [Try API](#try-api).
+
 ## Sending data
 
 The `send` method post a message on the channel as shown below:
@@ -107,11 +109,11 @@ $ cargo run --target thumbv7m-none-eabi --example async-channel-no-receiver --fe
 {{#include ../../../../rtic/ci/expected/async-channel-no-receiver.run}}
 ```
 
-
-
 ## Try API
 
-In cases you wish the sender to proceed even in case the channel is full. To that end, a `try_send` API is provided.
+Using the Try API, you can send or receive data from or to a channel without requiring that the operation succeeds, and in non-`async` contexts.
+
+This API is exposed through `Receiver::try_recv` and `Sender::try_send`.
 
 ``` rust
 {{#include ../../../../rtic/examples/async-channel-try.rs}}
diff --git a/rtic/examples/async-channel-try.rs b/rtic/examples/async-channel-try.rs
index 54a51d9..2e2af52 100644
--- a/rtic/examples/async-channel-try.rs
+++ b/rtic/examples/async-channel-try.rs
@@ -18,7 +18,9 @@ mod app {
     struct Shared {}
 
     #[local]
-    struct Local {}
+    struct Local {
+        sender: Sender<'static, u32, CAPACITY>,
+    }
 
     const CAPACITY: usize = 1;
     #[init]
@@ -28,7 +30,7 @@ mod app {
         receiver::spawn(r).unwrap();
         sender1::spawn(s.clone()).unwrap();
 
-        (Shared {}, Local {})
+        (Shared {}, Local { sender: s.clone() })
     }
 
     #[task]
@@ -45,4 +47,11 @@ mod app {
         hprintln!("Sender 1 try sending: 2 {:?}", sender.try_send(2));
         debug::exit(debug::EXIT_SUCCESS); // Exit QEMU simulator
     }
+
+    // This interrupt is never triggered, but is used to demonstrate that
+    // one can (try to) send data into a channel from a hardware task.
+    #[task(binds = GPIOA, local = [sender])]
+    fn hw_task(cx: hw_task::Context) {
+        cx.local.sender.try_send(3).ok();
+    }
 }