The **WMS2-A2-R/Q** is a high-performance, compact **Micro-Wave Motion Sensor Module**. It is widely used in intelligent lighting, security systems, and smart home devices. Unlike traditional PIR (Passive Infrared) sensors that detect heat, this module uses the **Doppler Effect** to detect motion through electromagnetic waves. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Operating Frequency** | 5.8 GHz ± 75MHz (C-Band) | | **Operating Voltage** | 4.5V – 5.5V DC (Typical 5V) | | **Operating Current** | 30mA – 50mA | | **Detection Distance** | 2 – 12 Meters (Adjustable) | | **Output Signal** | 0V / 3.3V (High/Low TTL Level) | | **Delay Time** | 2s – 120s (Adjustable) | | **Detection Angle** | 360° (Ceiling) / 180° (Wall) | --- ### 2. Core Electronic Components The module is integrated into a small PCB (Printed Circuit Board) containing several critical electronic sections: 1. **Planar Antenna:** A patch antenna etched directly onto the PCB. It transmits a continuous low-power microwave signal and receives the reflected signal. 2. **Microwave Oscillator:** Generates the 5.8GHz frequency. This frequency is preferred over 2.4GHz or 10GHz because it offers a good balance between penetration (can go through plastic, glass, and thin walls) and sensitivity. 3. **Signal Processor (ASIC/MCU):** The "brain" of the module. It compares the frequency of the transmitted wave with the received wave. If there is a shift (Doppler shift), it identifies motion. 4. **Potentiometers (R/Q variants):** * **Distance Adj:** Controls the sensitivity/radius of detection. * **Time Adj:** Controls how long the output remains "High" after motion is detected. 5. **LDO Regulator:** Ensures the internal circuitry receives a stable voltage, protecting the microwave components from power fluctuations. --- ### 3. Pinout Definition The module typically features a 3-pin or 5-pin interface for easy integration: | Pin | Label | Description | | :--- | :--- | :--- | | 1 | **VCC** | Positive Power Input (5V) | | 2 | **OUT** | Control Signal Output (High = Motion, Low = Idle) | | 3 | **GND** | Ground | --- ### 4. Advantages vs. PIR Sensors * **Penetration:** Can be hidden inside a plastic lamp cover or behind a thin wooden panel (invisible installation). * **Environmentally Stable:** Not affected by ambient temperature, smoke, or wind (PIR sensors often fail in hot environments). * **Sensitivity:** Capable of detecting very slight movements, such as a person breathing or typing. --- ### 5. Application Circuit Example ```cpp // Basic Arduino Logic for WMS2-A2-R/Q int sensorPin = 2; // Connected to OUT pin int ledPin = 13; void setup() { pinMode(sensorPin, INPUT); pinMode(ledPin, OUTPUT); } void loop() { int val = digitalRead(sensorPin); if (val == HIGH) { digitalWrite(ledPin, HIGH); // Motion detected } else { digitalWrite(ledPin, LOW); // No motion } } ```