Use 2 tasks in usb echo example

examples/usb_echo.rs

@@ -1,39 +1,48 @@
 //! Example USB echo
 //!
-//! Uses a Usb CDC class to echo the data received by the host
+//! Sets up the device to appear as a virtual serial port to the host.
+//! When the host sends data to this virtual serial port, the device receives it and then sends (echoes) the same data back to the host.
+//! Additionally, on enumeration complete, green LED is on, otherwise red LED is on.
 //!
 
 #![no_std]
 #![no_main]
 
 use defmt::{error, info};
-use portenta_h7::board::{self, Board, LedBlue, UsbBusImpl};
+use portenta_h7::board::{self, Board, LedGreen, LedRed, UsbBusImpl};
 use rtic::app;
 use rtic_monotonics::systick::prelude::*;
+use rtic_sync::{channel::*, make_channel};
 use static_cell::StaticCell;
 use usb_device::{class_prelude::UsbBusAllocator, prelude::*};
 use usbd_serial::CdcAcmClass;
 
 systick_monotonic!(Mono, 1000);
 
+#[derive(Clone, Copy, Debug, defmt::Format)]
+enum EnumerationState {
+    Complete,
+    Lost,
+}
+
+const CHANNEL_CAPACITY: usize = 1;
+type Msg = EnumerationState;
+
+const USB_MAX_PACKET_SIZE: usize = 64;
+const USB_BUS_BUFFER_SIZE: usize = 1024;
+
 #[app(device = portenta_h7::hal::pac, peripherals = false)]
 mod app {
     use super::*;
 
-    // USB buffers
-    const APP_BUFF_SIZE: usize = 64;
-    const USB_BUS_BUFFER_SIZE: usize = 1024;
-    static USB_BUS_BUFFER: StaticCell<[u32; USB_BUS_BUFFER_SIZE]> = StaticCell::new();
-    static USB_ALLOCATOR: StaticCell<UsbBusAllocator<UsbBusImpl>> = StaticCell::new();
-
     #[shared]
     struct Shared {}
 
     #[local]
     struct Local {
-        led_blue: LedBlue,
         usb_dev: UsbDevice<'static, UsbBusImpl>,
         usb_serial_port: CdcAcmClass<'static, UsbBusImpl>,
+        sender: Sender<'static, Msg, CHANNEL_CAPACITY>,
     }
 
     #[init]
@@ -43,14 +52,21 @@ mod app {
         Mono::start(cx.core.SYST, board::CORE_FREQUENCY.raw());
 
         // Get board resources
-        let Board { led_blue, usb, .. } = Board::take();
+        let Board {
+            led_red,
+            led_green,
+            usb,
+            ..
+        } = Board::take();
 
         // Init USB stack
+        static USB_BUS_BUFFER: StaticCell<[u32; USB_BUS_BUFFER_SIZE]> = StaticCell::new();
+        static USB_ALLOCATOR: StaticCell<UsbBusAllocator<UsbBusImpl>> = StaticCell::new();
         let usb_bus = USB_ALLOCATOR.init(UsbBusImpl::new(
             usb,
             USB_BUS_BUFFER.init([0; USB_BUS_BUFFER_SIZE]),
         ));
-        let usb_serial_port = usbd_serial::CdcAcmClass::new(usb_bus, APP_BUFF_SIZE as u16);
+        let usb_serial_port = usbd_serial::CdcAcmClass::new(usb_bus, USB_MAX_PACKET_SIZE as u16);
         let usb_dev = UsbDeviceBuilder::new(usb_bus, UsbVidPid(0x1234, 0xABCD))
             .device_class(usbd_serial::USB_CLASS_CDC)
             .max_packet_size_0(64)
@@ -62,25 +78,64 @@ mod app {
             .unwrap()
             .build();
 
+        // Create a channel to communicate between tasks
+        let (sender, receiver) = make_channel!(Msg, CHANNEL_CAPACITY);
+
+        info!("Spawning tasks");
+        let _ = led_control::spawn(led_red, led_green, receiver);
+
         (
             Shared {},
             Local {
-                led_blue,
                 usb_dev,
                 usb_serial_port,
+                sender,
             },
         )
     }
 
-    #[task(binds = OTG_HS, local = [led_blue, usb_dev, usb_serial_port])]
+    #[task(priority = 0)]
+    async fn led_control(
+        _cx: led_control::Context,
+        mut led_red: LedRed,
+        mut led_green: LedGreen,
+        mut receiver: Receiver<'static, Msg, CHANNEL_CAPACITY>,
+    ) {
+        // Initial state
+        led_red.on();
+
+        loop {
+            let msg = receiver.recv().await;
+            match msg {
+                Ok(data) => match data {
+                    EnumerationState::Complete => {
+                        info!("Enumeration complete");
+                        led_red.off();
+                        led_green.on();
+                    }
+                    EnumerationState::Lost => {
+                        info!("Enumeration lost");
+                        led_green.off();
+                        led_red.on();
+                    }
+                },
+
+                Err(_) => {
+                    error!("Error receiving message");
+                }
+            }
+        }
+    }
+
+    #[task(priority = 1, binds = OTG_HS, local = [usb_dev, usb_serial_port, sender])]
     fn usb_process(cx: usb_process::Context) {
         let (usb_dev, usb_serial_port) = (cx.local.usb_dev, cx.local.usb_serial_port);
         let previous_state = usb_dev.state();
 
         // Trigger internal state machine. It should be called either from ISR on USB event,
         // or every 10 ms from normal execution context
         if usb_dev.poll(&mut [usb_serial_port]) {
-            let mut app_buff = [0u8; APP_BUFF_SIZE];
+            let mut app_buff = [0u8; USB_MAX_PACKET_SIZE];
 
             // Read from reception fifo
             match usb_serial_port.read_packet(&mut app_buff) {
@@ -104,17 +159,17 @@ mod app {
 
         // Signal enumeration status
         match usb_dev.state() {
-            // Transition to enumeration
+            // Enumeration complete
             UsbDeviceState::Configured if previous_state == UsbDeviceState::Addressed => {
-                info!("Enumeration completed");
-                cx.local.led_blue.on();
+                let _ = cx.local.sender.try_send(EnumerationState::Complete);
             }
-            // Already enumerated
-            UsbDeviceState::Configured => {}
+
             // Enumeration lost
-            _ if previous_state == UsbDeviceState::Configured => {
-                info!("Enumeration lost");
-                cx.local.led_blue.off();
+            state
+                if previous_state == UsbDeviceState::Configured
+                    && state != UsbDeviceState::Configured =>
+            {
+                let _ = cx.local.sender.try_send(EnumerationState::Lost);
             }
             _ => (),
         }

examples/usb_led_ctrl.rs

@@ -161,7 +161,9 @@ mod app {
                         }
                     }
                 }
-                _ => error!("Msg receive error"),
+                Err(_) => {
+                    error!("Error receiving message");
+                }
             }
         }
     }