Added some validation checks, and the app now detects the charging state.

src/lib.rs

@@ -6,6 +6,12 @@ const VENDOR_IDS: [u16; 2] = [0x0951, 0x03F0];
 // Possible Cloud II Wireless product IDs
 const PRODUCT_IDS: [u16; 2] = [0x1718, 0x018B];
 
+const BATTERY_LEVEL_INDEX: usize = 7;
+const CHARGING_INDEX: usize = 5;
+const CHARGING_STATE: u8 = 0x10;
+const NOT_CHARGING_STATE: u8 = 0xF;
+const PREAMBLE: [u8; 5] = [6, 255, 187, 2, 0];
+
 const BATTERY_PACKET: [u8; 20] = {
     let mut packet = [0; 20];
     (packet[0], packet[1], packet[2], packet[3]) = (0x06, 0xff, 0xbb, 0x02);
@@ -20,6 +26,8 @@ pub enum DeviceError {
     NoDeviceFound(),
     #[error("Error: No response. Is the headset turned on?")]
     HeadSetOff(),
+    #[error("Error: Unknown response.")]
+    UnknownResponse(),
 }
    
 pub struct Device {
@@ -39,7 +47,6 @@ impl Device {
         Ok(Device { hid_device })
     }
 
-    //TODO: implement charging
     pub fn get_battery_level(&self) -> Result<(u8, bool), DeviceError> {
         self.hid_device.write(&BATTERY_PACKET)?;
         let mut buf = [0u8; 8];
@@ -47,7 +54,14 @@ impl Device {
         if res == 0 {
             return Err(DeviceError::HeadSetOff());
         }
-        println!("Read: {:?}", &buf[..res]);
+        if !buf.starts_with(&PREAMBLE) {
-        Ok((buf[7], false))
+            return Err(DeviceError::UnknownResponse());
+        }
+        let charging = match buf[CHARGING_INDEX] {
+            CHARGING_STATE => true,
+            NOT_CHARGING_STATE => false,
+            _ => return Err(DeviceError::UnknownResponse()),
+        };
+        Ok((buf[BATTERY_LEVEL_INDEX], charging))
     }
 }

src/main.rs

@@ -16,4 +16,9 @@ fn main() {
         }
     };
     println!("Battery level: {}%", battery_level);
+    if charging {
+        println!("Charging");
+    } else {
+        println!("Not charging");
+    }
 }