I’ve been studying the Heart Rate Measurement Characteristic documentation in order to understand what each byte of the characteristic means. My understanding is that the least significant byte of the characteristic corresponds with the flag field. So this line of code (in an Android app) should return the flags:
characteristic.getIntValue(BluetoothGattCharacteristic.FORMAT_UINT8, 0);
Also, from the Android BluetoothGattCharacteristic documentation, it looks like the getProperties method should also return the flag field.
However, when I print both these values to the console, they are different.
code
Log.d(TAG, "Flags : " + Integer.toBinaryString(characteristic.getProperties()));
Log.d(TAG, "Byte 0: " + Integer.toBinaryString(characteristic.getIntValue(BluetoothGattCharacteristic.FORMAT_UINT8, 0)));
console output
byte data﹕ Flags : 10000
byte data﹕ Byte 0: 10110
I notice is it just the sensor contact status bits that are different. Is it just that these bits are not considered properties? Or do I have an incorrect assumption?
REFERENCES
HR Measurement Characteristic: https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.characteristic.heart_rate_measurement.xml
getProperties method: https://developer.android.com/reference/android/bluetooth/BluetoothGattCharacteristic.html#getProperties()