Android Programming - Getting Started with Bluetooth Low Energy - page 118

Once the sensors are enabled, it's possible to read the sensor. To manually read the sensor,
you'll issue a read request to the characteristic you want to read and wait for the response
in the callback (see “ATT operations” on page 26 and “Reading Characteristics and
Descriptors” on page 70 for further details). The read can be triggered by an event, such
as the push of a button or a timer that periodically polls the sensor. In this case, a test
button created in the Options menu triggers events. That button's onClick method calls
the following function to generate a read request:
// Start the read request
private void testButton ()
{
BluetoothGatt gatt ;
BluetoothGattCharacteristic c ;
if (! mBleWrapper . isConnected ()) {
return ;
}
Log . d ( LOGTAG , "testButton: Reading acc" );
gatt = mBleWrapper . getGatt ();
c = gatt . getService ( UUID_ACC_SERV ). getCharacteristic ( UUID_ACC_DATA );
mBleWrapper . requestCharacteristicValue ( c );
mState = ACC_READ ;
}
// Get the read response inside this callback
@Override
public void uiNewValueForCharacteristic ( BluetoothGatt gatt ,
BluetoothDevice device ,
BluetoothGattService service ,
BluetoothGattCharacteristic ch ,
String strValue ,
int intValue ,
byte [] rawValue ,
String timestamp )
{
super . uiNewValueForCharacteristic ( gatt , device , service ,
ch , strValue , intValue ,
rawValue , timestamp );
// decode current read operation
switch ( mState )
{
case ( ACC_READ ):
Log . d ( LOGTAG , "uiNewValueForCharacteristic: Accelerometer data:" );
break ;
}
// dump data byte array
for ( byte b: rawValue )
{