CC2540 keyfob Accelerometer data conversion

Hello Yogesh,

I am not fluent in Android, but you should be able to get a good understanding of what you need to do by following this basic example. http://www.byteworks.us/Byte_Works/Blog/Entries/2012/8/20_Controlling_Bluetooth_LE_Devices_with_techBASIC.html

There should also be an Android App with the source code for connecting to the KeyFob in the Smart Phone Example section of the BLE-wiki.http://processors.wiki.ti.com/index.php/CC254X_Smart_Phone_Examples

Thanks,

Hello greenja,

              Thank you for reply.From the link http://processors.wiki.ti.com/index.php/CC254X_Smart_Phone_Examples I downloaded the Source code for the “sensorTag” app. According to data conversion for Accelerometer sensor I applied the same logic in my code as follows:

 // Simplified code snippet …

@Override

public void onCharacteristicChanged( BluetoothGatt gatt, BluetoothGattCharacteristic characteristic ) {

           super.onCharacteristicChanged( gatt, characteristic );

           // After notifications are enabled, all updates from the device on characteristic value changes will be posted here.

           // The accelerometer has the range [-2g, 2g] with unit (1/64)g.

           // To convert from unit (1/64)g to unit g we divide by 64.

           // (g = 9.81 m/s^2)

           // The z value is multiplied with -1 to coincide with how we have arbitrarily defined the positive y direction. (illustrated by the apps accelerometer image)

            if( ACCEL_X_UUID.equals( characteristic.getUuid() ) ) {

                 // Handle the X-axis notification.

                  byte[] value = characteristic.getValue();  

                  Integer x = (int) value[0];

                 // Works fine, here gives value for movement along  x direction.

           } else if( ACCEL_Y_UUID.equals( characteristic.getUuid() ) ) {

                 // Handle the Y-axis notification. 

                 byte[] value = characteristic.getValue();  

                 Integer y = (int) value[1];

                 // error : ArrayIndexOutOfBoundsException

           } else if( ACCEL_Z_UUID.equals( characteristic.getUuid() ) ) {

                // Handle the Z-axis notification.

                byte[] value = characteristic.getValue();  

                Integer z = (int) value[2] * -1;

               // error : ArrayIndexOutOfBoundsException

        }

}

Is am I doing any wrong calculation? Can you find out why this issue occurs?

The X, Y and Z UUID are independent and so are their characteristics.  You are thinking of the data as being one large array.  They are three independent arrays.  Leave the value at value[0] for all of them.

Thanks,