The **KWMS2-GC-R/K** is a high-performance infrared (IR) motion sensor module typically used in modern appliances, particularly for gesture control and occupancy sensing in HVAC or lighting systems. Below is a detailed breakdown of its electronic components and functional characteristics. --- ## 1. Technical Specifications Overview The module combines an infrared thermopile sensor with specialized signal conditioning circuitry to detect heat signatures from the human body. | Feature | Specification | | :--- | :--- | | **Sensor Type** | Passive Infrared (PIR) / Thermopile | | **Detection Method** | Far-infrared radiation (FIR) sensing | | **Output Type** | Digital (I2C or PWM depending on configuration) | | **Operating Voltage** | Typically 3.3V to 5.0V DC | | **Detection Range** | Up to 5 meters (standard human motion) | | **Lens Type** | Fresnel Lens (optimized for wide-angle) | --- ## 2. Key Electronic Components ### A. The Infrared Sensing Element The "heart" of the module is a dual or quad-element thermopile sensor. Unlike standard PIR sensors that only detect movement, this series often employs sensors capable of detecting static presence by measuring the absolute temperature difference between the target and the environment. ### B. Signal Conditioning ASIC The board contains an **Application-Specific Integrated Circuit (ASIC)** that handles: * **Amplification:** Boosting the micro-volt signals from the IR element. * **A/D Conversion:** Transforming analog thermal data into digital values. * **Noise Filtering:** Removing interference from ambient light or electromagnetic fields (EMI). ### C. Optical Fresnel Lens The "GC" designation often refers to a specific lens geometry. This plastic cover focuses infrared energy onto the sensor element. * **Horizontal FOV:** Usually 80° to 100°. * **Vertical FOV:** Usually 60° to 80°. --- ## 3. Pinout and Interface The module typically uses a 3-pin or 4-pin connector for easy integration with microcontrollers (MCU). | Pin No. | Label | Function | | :--- | :--- | :--- | | 1 | **VDD** | Power Supply (Positive) | | 2 | **GND** | Ground | | 3 | **OUT/SDA** | Signal Output (High/Low) or Data line | | 4 (if present) | **SCL** | Clock line for I2C communication | --- ## 4. Operational Logic (The "K" Variant) The **-R/K** suffix usually denotes specialized sensitivity settings: * **R:** High resistance to white light interference (prevents false triggers from sunlight). * **K:** Enhanced sensitivity for "micro-motions" (e.g., typing or breathing), making it suitable for "Stay-On" lighting in offices. --- ## 5. Typical Application Circuit When connecting to an Arduino or ESP32, the wiring usually follows this structure: ```cpp // Example logic for KWMS2 digital output int sensorPin = 2; // Connected to OUT pin void setup() { pinMode(sensorPin, INPUT); Serial.begin(9600); } void loop() { int val = digitalRead(sensorPin); if (val == HIGH) { Serial.println("Motion Detected!"); } delay(100); } ```