SlideShare a Scribd company logo
USING ACCELEROMETERS AND OTHER
SENSORS IN JAVA ME ON SERIES 40


Attila Csipa [@achipa]
Technology Wizard, Nokia

 1     © 2012 Nokia Using accelerometers and other sensors in Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
CONTENTS
• Introduction
     – Platforms & Versions
• Sensors
     –   Physical vs virtual
     –   JSR-256
     –   Measurables
     –   Accelerometers
     –   Usage
     –   UI considerations
     –   Performance
     –   App Compatibility
• Resources



 2          © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
PLATFORMS
API Differences: bit.ly/S40Apis




5th Ed., FP1    6th Ed., Lite            6th Ed.              6th Ed., FP1                  DP 1.0                       DP 1.1   Developer Platform 2.0




          http://www.developer.nokia.com/Devices/Device_specifications/Comparison.xhtml?dev=Asha_306,Nokia_Asha_309,Asha_311


 3             © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
DP 2.0 – NEW APIS

         Full touch                                  Sensors &                                        Multipoint
              UI                                     Orientation                                      Touch APIs

         Gestures:                                       Virtual
                                                                                                                       ...
          Pinch                                         Keyboard

4   © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS
    Etymology
    Originated 1925–30 from sense + -or.

    Noun
    sensor (plural sensors)
    A device or organ that detects certain external stimuli and responds in a
    distinctive manner.


5         © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: PHYSICAL VS VIRTUAL
• Physical sensors (physical values, g or m/s, mbar, etc)
     – Acceleration
     – Light
     – ...
• Virtual sensors (combined or interpreted values, %, enum-s)
    – Battery level
    – Orientation
    –…
 6      © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: JSR-256
                                                                               JSR page at http://bit.ly/VdZDlG

• JSR 256 Sensor API
    – Generic: designed also for temperature, blood pressure, etc.
    – Support on Series40 from DP2.0 (Asha Full Touch)
    – Also available on Symbian (from S60 5th edition onwards)
• Two packages
        javax.microedition.sensor (read information)
        javax.microedition.sensor.control (settings, start/stop)
7      © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: WHAT TO LOOK FOR
• Currently supported
    – Battery Charge: 0 .. 100, charge percentage
    – Network Field Intensity: 0 .. 100, signal strength
    – Charger State: 0 .. 1, charger connected
    – Acceleration: –2g .. +2g, x / y / z axis
    – Double Tap: 1 .. 63, phone sides
    – Orientation: 0 .. 6, phone orientation


8      © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: ACCELEROMETERS ARE COOL
• Enrich user interaction
    – Doesn’t suffer from finger size limits
    – Doesn’t suffer from screen size limits
    – Doesn’t interfere with what the user sees on the screen
    – Natural interaction
• Ideal for games!


9      © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: UNDERSTANDING ACCELEROMETERS
• Acceleration is CHANGE of the speed vector
• Standstill normalized value is 1.0, why? GRAVITY
• Nitpick - accelerometers measure translation not rotation
• Rotation can still be measured indirectly (we measure
 gravity vector hopping from one axis to the other)



10    © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
Example:
SENSORS: API AVAILABILITY                                                                                                  Racer, aMaze



• No System property for the API version?
     – Check Class availability
     – ClassNotFoundException? → API not supported
       // Virtual keyboard support
       try {
           // Check if class is available
           Class.forName("javamicroedition.sensor.SensorConnection");
           // SensorManager.findSensors("acceleration", null);
           useSensors = true;
       } catch (ClassNotFoundException e) {
           // Class not available: -> no Sensor API support.
           useSensors = false;
       } catch (Exception e) { }



11      © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
Example: MovingBall
SENSORS: USING THEM – ROLL YOUR OWN
• Establish sensor connection
     // Find all acceleration sensors, the contextType is left undefined
     SensorInfo[] sensorInfos = SensorManager.findSensors("acceleration", null);
     // Find an acceleration sensor that returns double values
     for (int i = 0; i < sensorInfos.length; i++) {
         if (sensorInfos[i].getChannelInfos()[0].getDataType() == ChannelInfo.TYPE_DOUBLE) {
             accSensor = (SensorConnection) Connector.open(sensorInfos[i].getUrl());
         }
     }


• Check data in game loop
     // Use   1 as a buffer size to get exactly 1 value for each axis
     Data[]   data = accSensor.getData(1);
     speedX   = -data[0].getDoubleValues()[0]; // data[0] => x-axis
     speedY   = data[1].getDoubleValues()[0];   // data[1] => y-axis




12            © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: USING THEM – COPY WITH PRIDE
• Use the wrapping classes from Nokia Developer examples
     private void enableSensors() {
         if (accelerationProvider != null) {
             accelerationProvider.close();
         }
         accelerationProvider = AccelerationProvider.getProvider(
             new AccelerationProvider.Listener() {
                  public void dataReceived(double ax, double ay, double az) {
                      if (isSensorTurning()) {
                          tilt = (int) ay;
                      }
                 }
             });
         if (accelerationProvider != null) {
             Main.sensorsSupported = true;
         } else {
             Main.sensorsSupported = false;
         }
     }

13          © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: UI CONSIDERATIONS
• Calibrate! (see aMaze example)
• Look for change, not particular values
• Which axis is which (portrait vs landscape)
• Anticipate noise in readings (average values if needed)
• Don’t force accelerometer usage if it doesn’t add to the
 user experience

14    © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
SENSORS: PERFORMANCE
• Filter (LimitCondition) for values you’re really interested in
• Separate from mainloop – use Threads (see Cottage360
 video and source)
• Responsiveness is more critical than with keyboard input
• Choose right frequency (is 100 reads/sec really needed?)



15    © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
COMPATIBILITY




16   © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
COMPATIBILITY? CODE CONSIDERATIONS
• Source & binary compatible
    – xx years old Java ME apps run on
      full touch phones (and vice versa)!
• Downwards compatibility
     – Check API support of target phones
     – Lowest common denominator:
         → Nokia Java SDK 2.0 compiled app
         runs on old phones


17      © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
COMPATIBILITY? USE-CASE CONSIDERATIONS
• Input type
     – Sensors complementing buttons (universal)
         – Discrete input CAN be easier with buttons (f.ex Snake)!
     – Sensors complementing touch controls (touch&type)
         – Most common
     – Accelerometer only (no pre-DP2.0)
         – Rarer than you think, but possible! (f.ex wire loop game)


18      © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
DYNAMIC API USAGE
• Single code base for different phones
     – Code that uses new APIs
         – Externalize to extra class
     – Check API support at runtime
         – Instantiate class if supported
         – Different methods for checking available




19      © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
RESOURCES & TIPS




22   © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
NOKIA IDE FOR JAVA ME
     Integrated SDK + Toolchain                                                                                           JAD Editor




     App Templates                                                                                        Device SDK Manager


23     © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
CODE EXAMPLES
• Nokia IDE
      – Nokia Hub → Nokia Series 40
        Code Examples
• Online
      – bit.ly/JavaMeExamples
• Emulator
      – Help → MIDlet Samples
• Maps & LWUIT
      – C:NokiadevicesNokia_SDK_2_0_Javaplugins



 24       © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
CODE EXAMPLES SHOWN TODAY
• Wiki
• aMaze
• Racer
• Cottage360 (episode 19)




25       © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
GET STARTED
• Overview
     – www.developer.nokia.com/Develop/Java/Getting_started/
• Downloads
     – SDK: www.developer.nokia.com/Develop/Java/
     – LWUIT: projects.developer.nokia.com/LWUIT_for_Series_40
• Guides
     –   Design & User Experience
     –   Porting from Android
     –   www.developer.nokia.com/Develop/Java/Documentation/
     –   Training Videos: www.developer.nokia.com/Develop/Java/Learning/
     –   Code Examples: www.developer.nokia.com/Develop/Java/Code_examples/

27         © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
THANK YOU!                                                      QUESTIONS?
Want to learn more?
www.developer.nokia.com

Attila Csipa [@achipa]
Technology Wizard, Nokia



 28    © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa

More Related Content

Using sensors in java me apps on series 40

  • 1. USING ACCELEROMETERS AND OTHER SENSORS IN JAVA ME ON SERIES 40 Attila Csipa [@achipa] Technology Wizard, Nokia 1 © 2012 Nokia Using accelerometers and other sensors in Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 2. CONTENTS • Introduction – Platforms & Versions • Sensors – Physical vs virtual – JSR-256 – Measurables – Accelerometers – Usage – UI considerations – Performance – App Compatibility • Resources 2 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 3. PLATFORMS API Differences: bit.ly/S40Apis 5th Ed., FP1 6th Ed., Lite 6th Ed. 6th Ed., FP1 DP 1.0 DP 1.1 Developer Platform 2.0 http://www.developer.nokia.com/Devices/Device_specifications/Comparison.xhtml?dev=Asha_306,Nokia_Asha_309,Asha_311 3 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 4. DP 2.0 – NEW APIS Full touch Sensors & Multipoint UI Orientation Touch APIs Gestures: Virtual ... Pinch Keyboard 4 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 5. SENSORS Etymology Originated 1925–30 from sense + -or. Noun sensor (plural sensors) A device or organ that detects certain external stimuli and responds in a distinctive manner. 5 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 6. SENSORS: PHYSICAL VS VIRTUAL • Physical sensors (physical values, g or m/s, mbar, etc) – Acceleration – Light – ... • Virtual sensors (combined or interpreted values, %, enum-s) – Battery level – Orientation –… 6 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 7. SENSORS: JSR-256 JSR page at http://bit.ly/VdZDlG • JSR 256 Sensor API – Generic: designed also for temperature, blood pressure, etc. – Support on Series40 from DP2.0 (Asha Full Touch) – Also available on Symbian (from S60 5th edition onwards) • Two packages javax.microedition.sensor (read information) javax.microedition.sensor.control (settings, start/stop) 7 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 8. SENSORS: WHAT TO LOOK FOR • Currently supported – Battery Charge: 0 .. 100, charge percentage – Network Field Intensity: 0 .. 100, signal strength – Charger State: 0 .. 1, charger connected – Acceleration: –2g .. +2g, x / y / z axis – Double Tap: 1 .. 63, phone sides – Orientation: 0 .. 6, phone orientation 8 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 9. SENSORS: ACCELEROMETERS ARE COOL • Enrich user interaction – Doesn’t suffer from finger size limits – Doesn’t suffer from screen size limits – Doesn’t interfere with what the user sees on the screen – Natural interaction • Ideal for games! 9 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 10. SENSORS: UNDERSTANDING ACCELEROMETERS • Acceleration is CHANGE of the speed vector • Standstill normalized value is 1.0, why? GRAVITY • Nitpick - accelerometers measure translation not rotation • Rotation can still be measured indirectly (we measure gravity vector hopping from one axis to the other) 10 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 11. Example: SENSORS: API AVAILABILITY Racer, aMaze • No System property for the API version? – Check Class availability – ClassNotFoundException? → API not supported // Virtual keyboard support try { // Check if class is available Class.forName("javamicroedition.sensor.SensorConnection"); // SensorManager.findSensors("acceleration", null); useSensors = true; } catch (ClassNotFoundException e) { // Class not available: -> no Sensor API support. useSensors = false; } catch (Exception e) { } 11 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 12. Example: MovingBall SENSORS: USING THEM – ROLL YOUR OWN • Establish sensor connection // Find all acceleration sensors, the contextType is left undefined SensorInfo[] sensorInfos = SensorManager.findSensors("acceleration", null); // Find an acceleration sensor that returns double values for (int i = 0; i < sensorInfos.length; i++) { if (sensorInfos[i].getChannelInfos()[0].getDataType() == ChannelInfo.TYPE_DOUBLE) { accSensor = (SensorConnection) Connector.open(sensorInfos[i].getUrl()); } } • Check data in game loop // Use 1 as a buffer size to get exactly 1 value for each axis Data[] data = accSensor.getData(1); speedX = -data[0].getDoubleValues()[0]; // data[0] => x-axis speedY = data[1].getDoubleValues()[0]; // data[1] => y-axis 12 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 13. SENSORS: USING THEM – COPY WITH PRIDE • Use the wrapping classes from Nokia Developer examples private void enableSensors() { if (accelerationProvider != null) { accelerationProvider.close(); } accelerationProvider = AccelerationProvider.getProvider( new AccelerationProvider.Listener() { public void dataReceived(double ax, double ay, double az) { if (isSensorTurning()) { tilt = (int) ay; } } }); if (accelerationProvider != null) { Main.sensorsSupported = true; } else { Main.sensorsSupported = false; } } 13 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 14. SENSORS: UI CONSIDERATIONS • Calibrate! (see aMaze example) • Look for change, not particular values • Which axis is which (portrait vs landscape) • Anticipate noise in readings (average values if needed) • Don’t force accelerometer usage if it doesn’t add to the user experience 14 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 15. SENSORS: PERFORMANCE • Filter (LimitCondition) for values you’re really interested in • Separate from mainloop – use Threads (see Cottage360 video and source) • Responsiveness is more critical than with keyboard input • Choose right frequency (is 100 reads/sec really needed?) 15 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 16. COMPATIBILITY 16 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 17. COMPATIBILITY? CODE CONSIDERATIONS • Source & binary compatible – xx years old Java ME apps run on full touch phones (and vice versa)! • Downwards compatibility – Check API support of target phones – Lowest common denominator: → Nokia Java SDK 2.0 compiled app runs on old phones 17 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 18. COMPATIBILITY? USE-CASE CONSIDERATIONS • Input type – Sensors complementing buttons (universal) – Discrete input CAN be easier with buttons (f.ex Snake)! – Sensors complementing touch controls (touch&type) – Most common – Accelerometer only (no pre-DP2.0) – Rarer than you think, but possible! (f.ex wire loop game) 18 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 19. DYNAMIC API USAGE • Single code base for different phones – Code that uses new APIs – Externalize to extra class – Check API support at runtime – Instantiate class if supported – Different methods for checking available 19 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 20. RESOURCES & TIPS 22 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 21. NOKIA IDE FOR JAVA ME Integrated SDK + Toolchain JAD Editor App Templates Device SDK Manager 23 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 22. CODE EXAMPLES • Nokia IDE – Nokia Hub → Nokia Series 40 Code Examples • Online – bit.ly/JavaMeExamples • Emulator – Help → MIDlet Samples • Maps & LWUIT – C:NokiadevicesNokia_SDK_2_0_Javaplugins 24 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 23. CODE EXAMPLES SHOWN TODAY • Wiki • aMaze • Racer • Cottage360 (episode 19) 25 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 24. GET STARTED • Overview – www.developer.nokia.com/Develop/Java/Getting_started/ • Downloads – SDK: www.developer.nokia.com/Develop/Java/ – LWUIT: projects.developer.nokia.com/LWUIT_for_Series_40 • Guides – Design & User Experience – Porting from Android – www.developer.nokia.com/Develop/Java/Documentation/ – Training Videos: www.developer.nokia.com/Develop/Java/Learning/ – Code Examples: www.developer.nokia.com/Develop/Java/Code_examples/ 27 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa
  • 25. THANK YOU! QUESTIONS? Want to learn more? www.developer.nokia.com Attila Csipa [@achipa] Technology Wizard, Nokia 28 © 2012 Nokia Using accelerometers and other sensors from Java ME on Series 40 v1.1 October 23, 2012 Attila Csipa