Proximity Sensor

Proximity sensors detect the presence of objects without physically touching them. They are often used as a touch-less switch, automatically turning on faucets and opening doors to name a few examples.

MetaDetector boards are outfitted with the TSL2671 proximity detector, a photoelectric style detector that refelcts an infrared signal off the target object to measure distance. This sensor is accessed with the ProximityTsl2671 interface.

import com.mbientlab.metawear.module.ProximityTsl2671;

final ProximityTsl2671 proximity = board.getModule(ProximityTsl2671.class);

Configuration

The TSL2671 device has 4 configurable parameters that control the sensitivity and distance at which the detector can measure proximity. These parameters are set with the interface’s ConfigEditor class.

Parameter	Description
Integration Time	How long the internal ADC converts analog input into digital counts
Pulse Count	Number of IR pulses emitted for distance measuring
Receiver Diode	Which photodiode to use for measure incoming light
Transmitter Current	Amount of current driving the IR transmitter

import com.mbientlab.metawear.module.ProximityTsl2671.ReceiverDiode;
import com.mbientlab.metawear.module.ProximityTsl2671.TransmitterDriveCurrent;

// set integration time to 5.44ms
// use both photodiodes for proximity detection
// use default pulse count of 1,
// set drive current to 25mA
proximity.configure()
        .integrationTime(5.44f)
        .receiverDiode(ReceiverDiode.BOTH)
        .transmitterDriveCurrent(TransmitterDriveCurrent.CURRENT_25MA)
        .commit();

Proximity Data

Proximity data is an ADC value represented as an unsigned short; the higher the adc value, the closeer the distance to the object.

proximity.adc().addRouteAsync(new RouteBuilder() {
    @Override
    public void configure(RouteComponent source) {
        source.stream(new Subscriber() {
            @Override
            public void apply(Data data, Object ... env) {
                Log.i("MainActivity", "Proximity ADC = " + data.value(Integer.class));
            }
        });
    }
}).continueWith(new Continuation<Route, Void>() {
    @Override
    public Void then(Task<Route> task) throws Exception {
        proximity.adc().read();
        return null;
    }
});