Fix Checksum

Change default timeout in TryGetUserCount

WaveshareUARTFingerprintSensor.Sample/Program.cs

@@ -19,7 +19,11 @@ namespace WaveshareUARTFingerprintSensor.Sample
 
             sensor.Start();
 
-            var count = sensor.GetUserCount();
+            sensor.Waked += s => sensor.Wake();
+
+            sensor.Sleep();
+
+            Console.WriteLine("End");
 
             Thread.Sleep(-1);
         }

WaveshareUARTFingerprintSensor/FingerprintSensor.cs

@@ -17,6 +17,10 @@ namespace WaveshareUARTFingerprintSensor
     {
         public const string PrimarySerialPort = "/dev/ttyAMA0";
         public const string SecondarySerialPort = "/dev/ttyS0";
+        public const int DefaultTimeout = 10_000;
+
+        public event WakedEventHandler Waked;
+        public delegate void WakedEventHandler(FingerprintSensor sender);
 
         public string PortName { get; }
 
@@ -62,19 +66,22 @@ namespace WaveshareUARTFingerprintSensor
 
             for (int i = 1; i < 6; i++)
             {
-                checksum += data[i];
+                checksum ^= data[i];
             }
 
             return checksum;
         }
 
-        private (byte first, byte second, ResponseType responseType) SendAndReceive(CommandType commandType, byte first, byte second, byte third)
+        private (byte first, byte second, ResponseType responseType) SendAndReceive(CommandType commandType, byte first, byte second, byte third, int timeout = DefaultTimeout)
         {
             // Command packet
             byte[] buffer = { PacketSeparator, (byte)commandType, first, second, third, 0, 0, PacketSeparator };
 
             lock (_lock)
             {
+                // Set timeout
+                _serialPort.WriteTimeout = timeout;
+                _serialPort.ReadTimeout = timeout;
 
                 // Checksum
                 buffer[6] = ComputeChecksum(buffer);
@@ -98,47 +105,66 @@ namespace WaveshareUARTFingerprintSensor
             return (buffer[2], buffer[3], (ResponseType)buffer[4]);
         }
 
-        /*
-        private void Send(CommandType commandType, byte first, byte second, byte third)
+        private (byte first, byte second, byte third) SendAndReceiveRaw(CommandType commandType, byte first, byte second, byte third, int timeout = DefaultTimeout)
         {
-            // Command packet
-            byte[] buffer = { PacketSeparator, (byte)commandType, first, second, third, 0, 0, PacketSeparator };
+            (byte f, byte s, ResponseType response) = SendAndReceive(commandType, first, second, third, timeout);
 
-            // Checksum
-            buffer[6] = ComputeChecksum(buffer);
-
-            _serialPort.Write(buffer, 0, buffer.Length);
+            return (f, s, (byte)response);
         }
 
-        private (byte first, byte second, byte third) Receive(CommandType commandType)
+        private bool TrySendAndReceive(CommandType commandType, byte first, byte second, byte third, out (byte first, byte second, ResponseType responseType) response, int timeout = DefaultTimeout)
         {
-            // Response buffer
-            var buffer = new byte[8];
-
-            // Response
-            _serialPort.Read(buffer, 0, buffer.Length);
-
-            if (buffer[0] != PacketSeparator || buffer[7] != PacketSeparator || buffer[1] != (byte)commandType)
+            try
             {
-                throw new InvalidDataException("Invalid response from the sensor");
+                response = SendAndReceive(commandType, first, second, third, timeout);
+            }
+            catch (Exception)
+            {
+                response = default;
+
+                return false;
             }
 
-            if (buffer[6] != ComputeChecksum(buffer))
-            {
-                throw new InvalidDataException("Invalid checksum");
-            }
-
-            return (buffer[2], buffer[3], buffer[4]);
+            return true;
+        }
+
+        private bool TrySendAndReceiveRaw(CommandType commandType, byte first, byte second, byte third, out (byte first, byte second, byte third) response, int timeout = DefaultTimeout)
+        {
+            try
+            {
+                response = SendAndReceiveRaw(commandType, first, second, third, timeout);
+            }
+            catch (Exception)
+            {
+                response = default;
+
+                return false;
+            }
+
+            return true;
+        }
+
+        public uint QuerySerialNumber()
+        {
+            (byte first, byte second, byte third) = SendAndReceiveRaw(CommandType.QuerySerialNumber, 0, 0, 0);
+
+            return Utils.Merge(first, second, third);
         }
-        */
 
         public bool TryGetUserCount(out ushort count)
         {
-            (byte countHigh, byte countLow, ResponseType response) = SendAndReceive(CommandType.QueryUserCount, 0, 0, 0);
+            if (TrySendAndReceive(CommandType.QueryUserCount, 0, 0, 0, out var response, 1000))
+            {
+                (byte countHigh, byte countLow, ResponseType responseType) = response;
 
-            count = Utils.Merge(countHigh, countLow);
+                count = Utils.Merge(countHigh, countLow);
 
-            return response == ResponseType.Success;
+                return responseType == ResponseType.Success;
+            }
+
+            count = default;
+
+            return false;
         }
 
         public void Sleep()
@@ -146,11 +172,16 @@ namespace WaveshareUARTFingerprintSensor
             _rstPin.Write(GpioPinValue.Low);
         }
 
+        public void Wake()
+        {
+            _rstPin.Write(GpioPinValue.High);
+        }
+
         private void OnWake()
         {
             if (_wakePin.Read())
             {
-                Console.WriteLine("Sensor WAKE signal received");
+                Waked?.Invoke(this);
             }
         }
 

WaveshareUARTFingerprintSensor/Utils.cs

@@ -9,7 +9,9 @@ namespace WaveshareUARTFingerprintSensor
     public static class Utils
     {
         public static ushort Merge(byte high, byte low) => (ushort)(high << 8 | low);
+        public static uint Merge(byte first, byte second, byte third) => (uint)(first << 16 | second << 8 | third);
 
         public static (byte high, byte low) Split(ushort value) => ((byte)(value >> 8), (byte)(value & 0xFF));
+        public static (byte first, byte second, byte third) Split(uint value) => ((byte)(value >> 16 & 0xFF), (byte)(value >> 8 & 0xFF), (byte)(value & 0xFF));
     }
 }