PAJ7620U2 gesture sensor

Iot.Device.Paj7620 is a .NET nanoFramework binding for the PixArt PAJ7620U2 gesture sensor.

Features

• I2C communication (0x73 default address)
• Device ID validation during initialization
• Seeed-compatible initialization sequence
• Gesture decoding for:
  • Up, Down, Left, Right
  • Forward, Backward
  • Clockwise, CounterClockwise
  • Wave

Usage

Create Paj7620, call Initialize(), then poll TryReadGesture(...).

using Iot.Device.Paj7620;
using System.Device.I2c;
using System.Diagnostics;
using System.Threading;
using nanoFramework.Hardware.Esp32;

Configuration.SetPinFunction(Gpio.IO05, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(Gpio.IO06, DeviceFunction.I2C1_CLOCK);

I2cConnectionSettings settings = new(1, Paj7620.DefaultI2CAddress);

using (Paj7620 sensor = new(I2cDevice.Create(settings)))
{
    sensor.GestureDebounceMilliseconds = 500;

    sensor.Initialize();
    Debug.WriteLine("PAJ7620 initialized.");

    while (true)
    {
        if (sensor.TryReadGesture(out Gesture gesture))
        {
            Debug.WriteLine($"Gesture: {gesture}");
        }

        Thread.Sleep(50);
    }
}

See https://github.com/nanoFramework/nanoFramework.IoT.Device/tree/main/devices/Paj7620/samples for a complete sample application.

Gesture mapping

The driver maps gesture result bitfields to the enum Gesture as follows:

• 0x0001 -> Up
• 0x0002 -> Down
• 0x0004 -> Left
• 0x0008 -> Right
• 0x0010 -> Forward
• 0x0020 -> Backward
• 0x0040 -> Clockwise
• 0x0080 -> CounterClockwise
• 0x0100 -> Wave

Notes

• The sensor requires successful Initialize() before reads.
• There is a default 500 ms debounce period after each detected gesture. This can be adjusted at runtime using sensor.GestureDebounceMilliseconds.
• Polling intervals between 20 ms and 100 ms are commonly stable in practice.
• Reliable detection depends on distance, hand speed, and ambient conditions.
• The sample uses I2C pins 5 (SDA) and 6 (SCL) on ESP32. Adjust pin configuration as needed for your board and wiring.