APDS-9960: Gesture, Proximity & Colour Sensor

Working Principle

The APDS-9960 from Broadcom (Avago) is a multi-function optical sensor integrating four capabilities in one 3.94 × 2.36 mm I²C package: gesture recognition, proximity detection, ambient light sensing, and RGB colour sensing. It uses an IR LED emitter paired with four directional photodiodes (up/down/left/right) to detect reflected IR and compute gesture direction and proximity distance. A separate clear + RGB photodiode array measures ambient light and colour temperature.

Gesture detection works by tracking differential IR reflectance across the four photodiodes as an object (typically a hand) moves across the sensor’s field of view, producing up, down, left, right data streams that an on-chip gesture engine resolves into directional events.

Electrical Characteristics

Parameter	Value
Supply Voltage	2.4–3.6 V
Interface	I²C (address 0x39, fixed)
Gesture Detection Range	10–30 cm
Proximity Range	~20 cm (8-bit output, 0–255)
ALS Dynamic Range	0.01–16,000 lux
Colour Channels	Clear, Red, Green, Blue (16-bit each)
LED Drive Current	12.5–100 mA (IR emitter, programmable)
Current Draw	~1 mA active, ~0.5 µA standby

Interfacing with an MCU

Connect VCC (3.3 V), GND, SDA, SCL, and the INT pin to an MCU GPIO (interrupt-driven gesture/proximity events). The sensor is I²C at a fixed address 0x39, so only one APDS-9960 per bus is possible without a multiplexer. Use the SparkFun or Adafruit APDS-9960 library for easy function access.

Calibration

• Proximity offset: The sensor has a hardware offset calibration register; run the offset calibration at startup to compensate for enclosure reflections
• Gesture sensitivity: Tune gesture enter/exit thresholds to avoid false triggers from nearby objects
• ALS integration time: Longer integration = more sensitivity in low light, but slower updates
• Colour correction: Apply IR rejection correction using the clear channel and published coefficients for accurate colour temperature

Code Example

/*
 * APDS-9960 Gesture + Proximity + Colour — Arduino
 * Library: SparkFun_APDS9960 (install via Library Manager)
 * Wiring: VCC → 3.3V, GND, SDA, SCL, INT → Pin 2
 */
#include <Wire.h>
#include <SparkFun_APDS9960.h>

SparkFun_APDS9960 apds;
volatile bool gestureFlag = false;

void gestureISR() { gestureFlag = true; }

void setup() {
    Serial.begin(9600);
    apds.init();
    apds.enableGestureSensor(true); /* INT on gesture */
    apds.enableProximitySensor(false);
    apds.enableLightSensor(false);
    attachInterrupt(0, gestureISR, FALLING);
    Serial.println("APDS-9960 Ready — wave hand over sensor");
}

void loop() {
    if (gestureFlag) {
        gestureFlag = false;
        if (apds.isGestureAvailable()) {
            switch (apds.readGesture()) {
                case DIR_UP:    Serial.println("UP");    break;
                case DIR_DOWN:  Serial.println("DOWN");  break;
                case DIR_LEFT:  Serial.println("LEFT");  break;
                case DIR_RIGHT: Serial.println("RIGHT"); break;
                default:        Serial.println("NONE");  break;
            }
        }
    }

    /* Also read proximity and colour periodically */
    uint8_t prox;
    uint16_t r, g, b, c;
    apds.readProximity(prox);
    apds.readAmbientLight(c);
    apds.readRedLight(r);
    apds.readGreenLight(g);
    apds.readBlueLight(b);

    Serial.print("Prox: "); Serial.print(prox);
    Serial.print("  R:"); Serial.print(r);
    Serial.print(" G:"); Serial.print(g);
    Serial.print(" B:"); Serial.println(b);
    delay(500);
}

Real-World Applications

Limitations

• Fixed I²C address: Only one sensor per bus (0x39); need a TCA9548A mux for multiple.
• Gesture range: Reliable only within 10–30 cm; not suitable for room-scale gesture detection.
• Ambient IR interference: Strong sunlight or IR sources can saturate the photodiodes and degrade gesture accuracy.
• 4 directions only: Basic up/down/left/right; cannot detect complex gestures like circles or pinches.