diff --git a/README.md b/README.md
index 0b4c995..2d1d21a 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ It consists of two components:
 * the input driver for your PC
 
 The GfxTablet app sends motion and touch events via UDP to a specified host
-on port 40117.
+on port 40118.
 
 The input driver must be installed on your PC. It creates a virtual "network tablet"
 on your PC that is controlled by your Android device.
diff --git a/app-android/AndroidManifest.xml b/app-android/AndroidManifest.xml
index c19dd71..9ff57d7 100644
--- a/app-android/AndroidManifest.xml
+++ b/app-android/AndroidManifest.xml
@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="at.bitfire.gfxtablet"
-    android:versionCode="1"
-    android:versionName="1.0" >
+    android:versionCode="2"
+    android:versionName="1.1" >
 
     <uses-sdk
         android:minSdkVersion="14"
diff --git a/app-android/src/at/bitfire/gfxtablet/CanvasActivity.java b/app-android/src/at/bitfire/gfxtablet/CanvasActivity.java
index 874286b..6513b13 100644
--- a/app-android/src/at/bitfire/gfxtablet/CanvasActivity.java
+++ b/app-android/src/at/bitfire/gfxtablet/CanvasActivity.java
@@ -35,7 +35,7 @@ public class CanvasActivity extends Activity {
 
 	@Override
 	protected void onDestroy() {
-		netClient.getQueue().add(new NetDisconnectEvent());
+		netClient.getQueue().add(new NetEvent(NetEvent.Type.TYPE_DISCONNECT));
 		super.onDestroy();
 	}
 	
diff --git a/app-android/src/at/bitfire/gfxtablet/CanvasView.java b/app-android/src/at/bitfire/gfxtablet/CanvasView.java
index 628018f..52cb10d 100644
--- a/app-android/src/at/bitfire/gfxtablet/CanvasView.java
+++ b/app-android/src/at/bitfire/gfxtablet/CanvasView.java
@@ -2,6 +2,7 @@ package at.bitfire.gfxtablet;
 
 import android.annotation.SuppressLint;
 import android.content.Context;
+import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
 import android.os.AsyncTask;
@@ -9,14 +10,14 @@ import android.preference.PreferenceManager;
 import android.view.MotionEvent;
 import android.view.View;
 import android.widget.Toast;
+import at.bitfire.gfxtablet.NetEvent.Type;
 
 @SuppressLint("ViewConstructor")
 public class CanvasView extends View implements OnSharedPreferenceChangeListener {
-	final static int PRESSURE_RESOLUTION = 10000;
-	
 	NetworkClient netClient;
 	SharedPreferences settings;
 	boolean acceptStylusOnly;
+	int maxX, maxY;
 	
 	public CanvasView(Context context, NetworkClient netClient) {
 		super(context);
@@ -47,8 +48,8 @@ public class CanvasView extends View implements OnSharedPreferenceChangeListener
 	
 	@Override
 	protected void onSizeChanged (int w, int h, int oldw, int oldh) {
-		Toast.makeText(getContext(), String.format("%dx%d", w, h), Toast.LENGTH_SHORT).show();
-		netClient.getQueue().add(new NetConfigurationEvent(w, h, PRESSURE_RESOLUTION));
+		maxX = w;
+		maxY = h;
 	}
 	
 	
@@ -59,7 +60,11 @@ public class CanvasView extends View implements OnSharedPreferenceChangeListener
 				if (!acceptStylusOnly || (event.getToolType(ptr) == MotionEvent.TOOL_TYPE_STYLUS)) {
 					//Log.i("XorgTablet", String.format("Generic motion event logged: %f|%f, pressure %f", event.getX(ptr), event.getY(ptr), event.getPressure(ptr)));
 					if (event.getActionMasked() == MotionEvent.ACTION_HOVER_MOVE)
-						netClient.getQueue().add(new NetMotionEvent((int)event.getX(ptr), (int)event.getY(ptr), (int)(event.getPressure(ptr)*PRESSURE_RESOLUTION)));
+						netClient.getQueue().add(new NetEvent(Type.TYPE_MOTION,
+							normalizeX(event.getX(ptr)),
+							normalizeY(event.getY(ptr)),
+							normalizePressure(event.getPressure(ptr))
+						));
 				}
 			return true;
 		}
@@ -71,17 +76,20 @@ public class CanvasView extends View implements OnSharedPreferenceChangeListener
 		if (isEnabled()) {
 			for (int ptr = 0; ptr < event.getPointerCount(); ptr++)
 				if (!acceptStylusOnly || (event.getToolType(ptr) == MotionEvent.TOOL_TYPE_STYLUS)) {
+					short nx = normalizeX(event.getX(ptr)),
+						  ny = normalizeY(event.getY(ptr)),
+						  npressure = normalizePressure(event.getPressure(ptr));
 					//Log.i("XorgTablet", String.format("Touch event logged: %f|%f, pressure %f", event.getX(ptr), event.getY(ptr), event.getPressure(ptr)));
 					switch (event.getActionMasked()) {
 					case MotionEvent.ACTION_MOVE:
-						netClient.getQueue().add(new NetMotionEvent((int)event.getX(ptr), (int)event.getY(ptr), (int)(event.getPressure(ptr)*PRESSURE_RESOLUTION)));
+						netClient.getQueue().add(new NetEvent(Type.TYPE_MOTION, nx, ny, npressure));
 						break;
 					case MotionEvent.ACTION_DOWN:
-						netClient.getQueue().add(new NetButtonEvent((int)event.getX(ptr), (int)event.getY(ptr), (int)(event.getPressure(ptr)*PRESSURE_RESOLUTION), true));
+						netClient.getQueue().add(new NetEvent(Type.TYPE_BUTTON, nx, ny, npressure, 0, true));
 						break;
 					case MotionEvent.ACTION_UP:
 					case MotionEvent.ACTION_CANCEL:
-						netClient.getQueue().add(new NetButtonEvent((int)event.getX(ptr), (int)event.getY(ptr), (int)(event.getPressure(ptr)*PRESSURE_RESOLUTION), false));
+						netClient.getQueue().add(new NetEvent(Type.TYPE_BUTTON, nx, ny, npressure, 0, false));
 						break;
 					}
 						
@@ -92,6 +100,19 @@ public class CanvasView extends View implements OnSharedPreferenceChangeListener
 	}
 	
 	
+	short normalizeX(float x) {
+		return (short)(Math.min(Math.max(0, x), maxX) * Short.MAX_VALUE/maxX);
+	}
+	
+	short normalizeY(float x) {
+		return (short)(Math.min(Math.max(0, x), maxY) * Short.MAX_VALUE/maxY);
+	}
+	
+	short normalizePressure(float x) {
+		return (short)(Math.min(Math.max(0, x), 2.0) * Short.MAX_VALUE/2.0);
+	}
+	
+	
 	private class ConfigureNetworkingTask extends AsyncTask<Void, Void, Boolean> {
 		@Override
 		protected Boolean doInBackground(Void... params) {
@@ -103,7 +124,8 @@ public class CanvasView extends View implements OnSharedPreferenceChangeListener
 				setEnabled(true);
 			else {
 				setEnabled(false);
-				Toast.makeText(getContext(), "Unknown host name, network tablet disabled!", Toast.LENGTH_LONG).show();
+				Toast.makeText(getContext(), "Unknown host name, please configure", Toast.LENGTH_LONG).show();
+				getContext().startActivity(new Intent(getContext(), SettingsActivity.class));
 			}
 		}
 	}
diff --git a/app-android/src/at/bitfire/gfxtablet/NetButtonEvent.java b/app-android/src/at/bitfire/gfxtablet/NetButtonEvent.java
deleted file mode 100644
index e1183c0..0000000
--- a/app-android/src/at/bitfire/gfxtablet/NetButtonEvent.java
+++ /dev/null
@@ -1,34 +0,0 @@
-package at.bitfire.gfxtablet;
-
-import java.io.ByteArrayOutputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-
-public class NetButtonEvent extends NetEvent {
-	boolean down;
-	
-	public NetButtonEvent(int x, int y, int pressure, boolean down) {
-		super(x, y, pressure);
-		this.down = down;
-	}
-
-	@Override
-	public byte[] toByteArray() {
-		ByteArrayOutputStream baos = new ByteArrayOutputStream();
-		DataOutputStream dos = new DataOutputStream(baos);
-		
-		try {
-			dos.write(1);	/* EVENT_TYPE_BUTTON */
-			dos.writeShort(x);
-			dos.writeShort(y);
-			dos.writeShort(pressure);
-			dos.write(1);
-			dos.write(down ? 1 : 0);
-		} catch (IOException e) {
-			return null;
-		}
-		
-		return baos.toByteArray();
-	}
-
-}
diff --git a/app-android/src/at/bitfire/gfxtablet/NetConfigurationEvent.java b/app-android/src/at/bitfire/gfxtablet/NetConfigurationEvent.java
deleted file mode 100644
index af52e04..0000000
--- a/app-android/src/at/bitfire/gfxtablet/NetConfigurationEvent.java
+++ /dev/null
@@ -1,28 +0,0 @@
-package at.bitfire.gfxtablet;
-
-import java.io.ByteArrayOutputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-
-public class NetConfigurationEvent extends NetEvent {
-	public NetConfigurationEvent(int x, int y, int pressure) {
-		super(x, y, pressure);
-	}
-
-	@Override
-	public byte[] toByteArray() {
-		ByteArrayOutputStream baos = new ByteArrayOutputStream();
-		DataOutputStream dos = new DataOutputStream(baos);
-		
-		try {
-			dos.write(2);	/* EVENT_TYPE_SET_RESOLUTION */
-			dos.writeShort(x);
-			dos.writeShort(y);
-			dos.writeShort(pressure);
-		} catch (IOException e) {
-			return null;
-		}
-		
-		return baos.toByteArray();
-	}
-}
diff --git a/app-android/src/at/bitfire/gfxtablet/NetDisconnectEvent.java b/app-android/src/at/bitfire/gfxtablet/NetDisconnectEvent.java
deleted file mode 100644
index 23fd1b3..0000000
--- a/app-android/src/at/bitfire/gfxtablet/NetDisconnectEvent.java
+++ /dev/null
@@ -1,12 +0,0 @@
-package at.bitfire.gfxtablet;
-
-public class NetDisconnectEvent extends NetEvent {
-	public NetDisconnectEvent() {
-		super(0, 0, 0);
-	}
-
-	@Override
-	public byte[] toByteArray() {
-		return null;
-	}
-}
diff --git a/app-android/src/at/bitfire/gfxtablet/NetEvent.java b/app-android/src/at/bitfire/gfxtablet/NetEvent.java
index fdb543b..7940396 100644
--- a/app-android/src/at/bitfire/gfxtablet/NetEvent.java
+++ b/app-android/src/at/bitfire/gfxtablet/NetEvent.java
@@ -1,17 +1,77 @@
 package at.bitfire.gfxtablet;
 
-public abstract class NetEvent {
-	int x, y, pressure;
-	
-	public int getX() { return x; }
-	public int getY() { return y; }
-	public int getPressure() { return pressure; }
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
 
-	public NetEvent(int x, int y, int pressure) {
-		this.x = Math.max(x, 0);
-		this.y = Math.max(y, 0);
+public class NetEvent {
+	enum Type {
+		TYPE_MOTION,
+		TYPE_BUTTON,
+		
+		// not specified in protocol, only needed to shut down network thread 
+		TYPE_DISCONNECT
+	};
+	static final String signature = "GfxTablet";
+	static final short protocol_version = 1;
+	
+	Type type;
+	short x, y, pressure;
+	byte button, button_down;
+	
+	public short getX() { return x; }
+	public short getY() { return y; }
+	public short getPressure() { return pressure; }
+	
+	
+	public NetEvent(Type type) {
+		this.type = type;
+	}
+
+	public NetEvent(Type type, short x, short y, short pressure) {
+		this.type = type;
+		this.x = x;
+		this.y = y;
 		this.pressure = pressure;
 	}
+	
+	public NetEvent(Type type, short x, short y, short pressure, int button, boolean button_down) {
+		this(type, x, y, pressure);
+		this.button = (byte)button;
+		this.button_down = (byte)(button_down ? 1 : 0);
+	}
 		
-	public abstract byte[] toByteArray();
+	public byte[] toByteArray() {
+		if (type == Type.TYPE_DISCONNECT)
+			return null;
+		
+		ByteArrayOutputStream baos = new ByteArrayOutputStream();
+		DataOutputStream dos = new DataOutputStream(baos);
+		
+		try {
+			dos.writeBytes(signature);
+			dos.writeShort(protocol_version);
+			
+			switch (type) {
+			case TYPE_MOTION:
+				dos.writeByte(0);
+				break;
+			case TYPE_BUTTON:
+				dos.writeByte(1);
+				break;
+			}
+			
+			dos.writeShort(x);
+			dos.writeShort(y);
+			dos.writeShort(pressure);
+			
+			if (type == Type.TYPE_BUTTON) {
+				dos.writeByte(button);
+				dos.writeByte(button_down);
+			}
+		} catch(IOException e) {
+		}
+		
+		return baos.toByteArray();
+	}
 }
diff --git a/app-android/src/at/bitfire/gfxtablet/NetMotionEvent.java b/app-android/src/at/bitfire/gfxtablet/NetMotionEvent.java
deleted file mode 100644
index a17eb32..0000000
--- a/app-android/src/at/bitfire/gfxtablet/NetMotionEvent.java
+++ /dev/null
@@ -1,28 +0,0 @@
-package at.bitfire.gfxtablet;
-
-import java.io.ByteArrayOutputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-
-public class NetMotionEvent extends NetEvent {
-	public NetMotionEvent(int x, int y, int pressure) {
-		super(x, y, pressure);
-	}
-
-	@Override
-	public byte[] toByteArray() {
-		ByteArrayOutputStream baos = new ByteArrayOutputStream();
-		DataOutputStream dos = new DataOutputStream(baos);
-		
-		try {
-			dos.write(0);	/* EVENT_TYPE_MOTION */
-			dos.writeShort(x);
-			dos.writeShort(y);
-			dos.writeShort(pressure);
-		} catch (IOException e) {
-			return null;
-		}
-		
-		return baos.toByteArray();
-	}
-}
diff --git a/app-android/src/at/bitfire/gfxtablet/NetworkClient.java b/app-android/src/at/bitfire/gfxtablet/NetworkClient.java
index 241a40c..69d5a4c 100644
--- a/app-android/src/at/bitfire/gfxtablet/NetworkClient.java
+++ b/app-android/src/at/bitfire/gfxtablet/NetworkClient.java
@@ -8,17 +8,17 @@ import java.util.concurrent.LinkedBlockingQueue;
 
 import android.content.SharedPreferences;
 import android.util.Log;
-
-// see "drivers" directory in Github repository for details about the protocol
+import at.bitfire.gfxtablet.NetEvent.Type;
 
 
 public class NetworkClient implements Runnable {
+	static int GFXTABLET_PORT = 40118;
+	
 	LinkedBlockingQueue<NetEvent> motionQueue = new LinkedBlockingQueue<NetEvent>();
 	LinkedBlockingQueue<NetEvent> getQueue() { return motionQueue; }
 	
 	InetAddress destAddress;
 	SharedPreferences preferences;
-	NetConfigurationEvent lastConfiguration = null;
 
 	NetworkClient(SharedPreferences preferences) {
 		this.preferences = preferences;
@@ -28,10 +28,6 @@ public class NetworkClient implements Runnable {
 		try {
 			String hostName = preferences.getString(SettingsActivity.KEY_PREF_HOST, "unknown.invalid");
 			destAddress = InetAddress.getByName(hostName);
-			
-			if (lastConfiguration != null)
-				motionQueue.add(lastConfiguration);
-	
 		} catch (UnknownHostException e) {
 			destAddress = null;
 			return false;
@@ -47,18 +43,15 @@ public class NetworkClient implements Runnable {
 			while (true) {
 				NetEvent event = motionQueue.take();
 				
-				// save resolution, even if not sending it
-				if (event.getClass() == NetConfigurationEvent.class)
-					lastConfiguration = (NetConfigurationEvent)event;
 				// graceful shutdown
-				else if (event.getClass() == NetDisconnectEvent.class)
+				if (event.type == Type.TYPE_DISCONNECT)
 					break;
 				
 				if (destAddress == null)		// no valid destination host
 					continue;
 			
 				byte[] data = event.toByteArray();
-				DatagramPacket pkt = new DatagramPacket(data, data.length, destAddress, 40117);
+				DatagramPacket pkt = new DatagramPacket(data, data.length, destAddress, GFXTABLET_PORT);
 				socket.send(pkt);
 			}
 		} catch (Exception e) {
diff --git a/doc/protocol.txt b/doc/protocol.txt
new file mode 100644
index 0000000..cdb7647
--- /dev/null
+++ b/doc/protocol.txt
@@ -0,0 +1,28 @@
+
+Network protocol used by GfxTablet
+
+
+
+Version 1
+---------
+
+GfxTablet app sends UDP packets to port 40118 of the destination host.
+
+Packet structure:
+
+  9  octets   "GfxTablet"
+  1  ushort   version number
+  1  ushort   type:
+              0 motion event (hovering)
+              1 button event (finger, pen etc. touches surface)
+
+  1  ushort   x (using full range: 0..65535)
+  1  ushort   y (using full range: 0..65535)
+  1  ushort   pressure (using full range 0..65535, 32768 == pressure 1.0f on Android device)
+
+when type == button event:
+  1  byte     number of button, starting with 0
+  1  byte     button status:
+              0 button is down
+              1 button is up
+
diff --git a/driver-uinput/Makefile b/driver-uinput/Makefile
index 4f7c547..9370e34 100644
--- a/driver-uinput/Makefile
+++ b/driver-uinput/Makefile
@@ -1,2 +1,2 @@
 
-networktablet : networktablet.c
+networktablet : networktablet.c protocol.h
diff --git a/driver-uinput/networktablet.c b/driver-uinput/networktablet.c
index dcd07cd..946f4b3 100644
--- a/driver-uinput/networktablet.c
+++ b/driver-uinput/networktablet.c
@@ -44,11 +44,11 @@ void init_device(int fd)
 	uidev.id.product = 0x1;
 	uidev.id.version = 1;
 	uidev.absmin[ABS_X] = 0;
-	uidev.absmax[ABS_X] = INT_MAX;
+	uidev.absmax[ABS_X] = SHRT_MAX;
 	uidev.absmin[ABS_Y] = 0;
-	uidev.absmax[ABS_Y] = INT_MAX;
+	uidev.absmax[ABS_Y] = SHRT_MAX;
 	uidev.absmin[ABS_PRESSURE] = 0;
-	uidev.absmax[ABS_PRESSURE] = 10000;	// 10,000 instead of 32,767 because sometimes there is pressure >1.0
+	uidev.absmax[ABS_PRESSURE] = SHRT_MAX/2;
 	if (write(fd, &uidev, sizeof(uidev)) < 0)
 		die("error: write");
 
@@ -66,7 +66,7 @@ int prepare_socket()
 
 	bzero(&addr, sizeof(struct sockaddr_in));
 	addr.sin_family = AF_INET;
-	addr.sin_port = htons(NETWORKTABLET_PORT);
+	addr.sin_port = htons(GFXTABLET_PORT);
 	addr.sin_addr.s_addr = htonl(INADDR_ANY);
 
 	if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) == -1)
@@ -90,8 +90,6 @@ int main(void)
 {
 	int device, socket;
 	struct event_packet ev_pkt;
-	int x, y, btn_down = 0;
-	int max_x = INT_MAX, max_y = INT_MAX;
 
 	if ((device = open("/dev/uinput", O_WRONLY | O_NONBLOCK)) < 0)
 		die("error: open");
@@ -99,34 +97,35 @@ int main(void)
 	init_device(device);
 	socket = prepare_socket();
 
-	while (recv(socket, &ev_pkt, sizeof(ev_pkt), 0) >= 7) {		// every packet has at least 7 bytes
+	while (recv(socket, &ev_pkt, sizeof(ev_pkt), 0) >= 9) {		// every packet has at least 9 bytes
 		printf("."); fflush(0);
 
+		if (memcmp(ev_pkt.signature, "GfxTablet", 9) != 0) {
+			fprintf(stderr, "\nGot unknown packet on port %i, ignoring\n", GFXTABLET_PORT);
+			continue;
+		}
+		ev_pkt.version = ntohs(ev_pkt.version);
+		if (ev_pkt.version != PROTOCOL_VERSION) {
+			fprintf(stderr, "\nGfxTablet app speaks protocol version %i but driver speaks version %i, please update\n",
+				ev_pkt.version, PROTOCOL_VERSION);
+			break;
+		}
+
 		ev_pkt.x = ntohs(ev_pkt.x);
 		ev_pkt.y = ntohs(ev_pkt.y);
 		ev_pkt.pressure = ntohs(ev_pkt.pressure);
-		//printf("x: %hi, y: %hi, pressure: %hi\n", ev_pkt.x, ev_pkt.y, ev_pkt.pressure);
+		printf("x: %hi, y: %hi, pressure: %hi\n", ev_pkt.x, ev_pkt.y, ev_pkt.pressure);
 
-		x = (long)ev_pkt.x * INT_MAX/max_x;
-		y = (long)ev_pkt.y * INT_MAX/max_y;
-
-		send_event(device, EV_ABS, ABS_X, x);
-		send_event(device, EV_ABS, ABS_Y, y);
+		send_event(device, EV_ABS, ABS_X, ev_pkt.x);
+		send_event(device, EV_ABS, ABS_Y, ev_pkt.y);
 		send_event(device, EV_ABS, ABS_PRESSURE, ev_pkt.pressure);
 
 		switch (ev_pkt.type) {
-			case EVENT_TYPE_SET_RESOLUTION: {
-				struct input_absinfo absinfo;
-				max_x = ev_pkt.x;
-				max_y = ev_pkt.y;
-				printf("Set resolution to %hix%hi\n", max_x+1, max_y+1);
-				break;
-			}
 			case EVENT_TYPE_MOTION:
 				send_event(device, EV_SYN, SYN_REPORT, 1);
 				break;
 			case EVENT_TYPE_BUTTON:
-				if (ev_pkt.button == 1)
+				if (ev_pkt.button == 0)
 					send_event(device, EV_KEY, BTN_TOUCH, ev_pkt.down);
 				send_event(device, EV_SYN, SYN_REPORT, 1);
 				break;
diff --git a/driver-uinput/protocol.h b/driver-uinput/protocol.h
index c3c00f6..fc9191f 100644
--- a/driver-uinput/protocol.h
+++ b/driver-uinput/protocol.h
@@ -1,16 +1,19 @@
 
-#define NETWORKTABLET_PORT 40117
+#define GFXTABLET_PORT 40118
+
+#define PROTOCOL_VERSION 1
 
 
 #pragma pack(push)
 #pragma pack(1)
 
-#define EVENT_TYPE_MOTION          0
-#define EVENT_TYPE_BUTTON          1
-#define EVENT_TYPE_SET_RESOLUTION  2
+#define EVENT_TYPE_MOTION 0
+#define EVENT_TYPE_BUTTON 1
 
 struct event_packet
 {
+	char signature[9];
+	unsigned short version;
 	char type;	/* EVENT_TYPE_... */
 	struct {	/* required */
 		short x, y;