Android Open Source - BleSensorTag Ti Pressure Sensor

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License

The source code is released under:

MIT License

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Java Source Code

package sample.ble.sensortag.sensor;
//w  ww . j a  v a 2  s .c om
import static java.lang.Math.pow;

import android.bluetooth.BluetoothGattCharacteristic;

import sample.ble.sensortag.ble.BleGattExecutor;

/**
 * Created by steven on 9/3/13.
 */
public class TiPressureSensor extends TiSensor<Double> {

    private static final String UUID_SERVICE = "f000aa40-0451-4000-b000-000000000000";
    private static final String UUID_DATA = "f000aa41-0451-4000-b000-000000000000";
    private static final String UUID_CONFIG = "f000aa42-0451-4000-b000-000000000000";
    private static final String UUID_CALIBRATION = "f000aa43-0451-4000-b000-000000000000";

    private static final byte[] CALIBRATION_DATA = new byte[] { 2 };

    private final int[] calibration = new int[8];

    TiPressureSensor() {
        super();
    }

    @Override
    public String getName() {
        return "Pressure";
    }

    @Override
    public String getServiceUUID() {
        return UUID_SERVICE;
    }

    @Override
    public String getDataUUID() {
        return UUID_DATA;
    }

    @Override
    public String getConfigUUID() {
        return UUID_CONFIG;
    }

    @Override
    public String getCharacteristicName(String uuid) {
        if (UUID_CALIBRATION.equals(uuid))
            return getName() + " Calibration";
        return super.getCharacteristicName(uuid);
    }

    @Override
    public boolean onCharacteristicRead(BluetoothGattCharacteristic c) {
        super.onCharacteristicRead(c);

        if ( !c.getUuid().toString().equals(UUID_CALIBRATION) )
            return false;

        for (int i=0; i<4; ++i) {
            calibration[i] = TiSensorUtils.shortUnsignedAtOffset(c, i * 2);
            calibration[i+4] = TiSensorUtils.shortSignedAtOffset(c, 8 + i * 2);
        }

        return true;
    }

    @Override
    public String getDataString() {
        final double data = getData();
        return ""+data;
    }

    @Override
    public BleGattExecutor.ServiceAction[] enable(boolean enable) {
        if (enable) {
            return new BleGattExecutor.ServiceAction[] {
                    write(UUID_CONFIG, CALIBRATION_DATA),
                    read(UUID_CALIBRATION),
                    write(getConfigUUID(), getConfigValues(enable)),
                    notify(enable)
            };
        } else {
            return super.enable(enable);
        }
    }

    @Override
    public Double parse(BluetoothGattCharacteristic c) {
        // c holds the calibration coefficients

        final Integer t_r;  // Temperature raw value from sensor
        final Integer p_r;  // Pressure raw value from sensor
        final Double t_a;   // Temperature actual value in unit centi degrees celsius
        final Double S;  // Interim value in calculation
        final Double O;  // Interim value in calculation
        final Double p_a;   // Pressure actual value in unit Pascal.

        t_r = TiSensorUtils.shortSignedAtOffset(c, 0);
        p_r = TiSensorUtils.shortUnsignedAtOffset(c, 2);

        t_a = (100 * (calibration[0] * t_r / pow(2,8) + calibration[1] * pow(2,6))) / pow(2,16);
        S = calibration[2] + calibration[3] * t_r / pow(2,17) + ((calibration[4] * t_r / pow(2,15)) * t_r) / pow(2,19);
        O = calibration[5] * pow(2,14) + calibration[6] * t_r / pow(2,3) + ((calibration[7] * t_r / pow(2,15)) * t_r) / pow(2,4);
        p_a = (S * p_r + O) / pow(2,14);

        return p_a;
    }

}

Java Source Code List