Add basic device state handling for endpoints.

examples/nrf/src/bin/usb_serial.rs

@@ -4,12 +4,13 @@
 #![feature(type_alias_impl_trait)]
 
 use core::mem;
-use defmt::*;
+use defmt::{info, panic};
 use embassy::executor::Spawner;
 use embassy_nrf::interrupt;
 use embassy_nrf::pac;
-use embassy_nrf::usb::Driver;
+use embassy_nrf::usb::{Driver, Instance};
 use embassy_nrf::Peripherals;
+use embassy_usb::driver::{ReadError, WriteError};
 use embassy_usb::{Config, UsbDeviceBuilder};
 use embassy_usb_serial::{CdcAcmClass, State};
 use futures::future::join;
@@ -66,12 +67,11 @@ async fn main(_spawner: Spawner, p: Peripherals) {
 
     // Do stuff with the class!
     let echo_fut = async {
-        let mut buf = [0; 64];
         loop {
-            let n = class.read_packet(&mut buf).await.unwrap();
-            let data = &buf[..n];
-            info!("data: {:x}", data);
-            class.write_packet(data).await.unwrap();
+            class.wait_connection().await;
+            info!("Connected");
+            let _ = echo(&mut class).await;
+            info!("Disconnected");
         }
     };
 
@@ -79,3 +79,35 @@ async fn main(_spawner: Spawner, p: Peripherals) {
     // If we had made everything `'static` above instead, we could do this using separate tasks instead.
     join(usb_fut, echo_fut).await;
 }
+
+struct Disconnected {}
+
+impl From<ReadError> for Disconnected {
+    fn from(val: ReadError) -> Self {
+        match val {
+            ReadError::BufferOverflow => panic!("Buffer overflow"),
+            ReadError::Disabled => Disconnected {},
+        }
+    }
+}
+
+impl From<WriteError> for Disconnected {
+    fn from(val: WriteError) -> Self {
+        match val {
+            WriteError::BufferOverflow => panic!("Buffer overflow"),
+            WriteError::Disabled => Disconnected {},
+        }
+    }
+}
+
+async fn echo<'d, T: Instance + 'd>(
+    class: &mut CdcAcmClass<'d, Driver<'d, T>>,
+) -> Result<(), Disconnected> {
+    let mut buf = [0; 64];
+    loop {
+        let n = class.read_packet(&mut buf).await?;
+        let data = &buf[..n];
+        info!("data: {:x}", data);
+        class.write_packet(data).await?;
+    }
+}