The **US-02-R** is a specialized ultrasonic distance sensor module, often characterized by its high precision and stable performance. It operates on the same principles as the common HC-SR04 but typically offers better resolution and a wider voltage range. --- ### 1. Key Technical Specifications The following table summarizes the primary electronic characteristics of the US-02-R module: | Parameter | Specification | | :--- | :--- | | **Operating Voltage** | DC 3V - 5.5V | | **Static Current** | Less than 2mA | | **Detection Distance** | 2cm – 450cm | | **Accuracy** | Up to 0.3cm + 1% | | **Sensing Angle** | < 15 degrees | | **Operating Temperature** | -20°C to +70°C | | **Output Type** | Pulse width (TTL level) | --- ### 2. Core Electronic Components The US-02-R circuit consists of three main functional blocks: 1. **Ultrasonic Transducer Pair:** * **Transmitter (T):** Converts electrical pulses into 40kHz ultrasonic sound waves. * **Receiver (R):** Receives the reflected sound waves and converts them back into electrical signals. 2. **Microcontroller (MCU):** * Onboard logic that processes the "Trigger" input, controls the transducer firing, and calculates the timing for the "Echo" output. 3. **Signal Processing Circuitry:** * Includes operational amplifiers to boost the weak signal received by the transducer and a comparator to convert the analog signal into a digital pulse. --- ### 3. Pin Configuration and Interface The module typically features a 4-pin interface compatible with most microcontrollers (Arduino, ESP32, Raspberry Pi). | Pin Name | Description | Connection | | :--- | :--- | :--- | | **VCC** | Power Supply | 3.3V or 5V | | **Trig** | Trigger Input | Digital Pin (Input) | | **Echo** | Echo Output | Digital Pin (Output) | | **GND** | Ground | System Ground | --- ### 4. Basic Operation Logic To get a distance reading, the electronic workflow follows these steps: 1. **Trigger:** Supply a 10µs High pulse to the **Trig** pin. 2. **Emission:** The module automatically sends eight 40kHz ultrasonic pulses. 3. **Reception:** The module waits for the reflection. 4. **Output:** The **Echo** pin goes HIGH the moment the sound is sent and returns to LOW when the reflection is received. The **duration** of this HIGH pulse is proportional to the distance. **Distance Calculation Formula:** ```python # Speed of sound is approx 340 m/s Distance = (High_Level_Time * 340) / 2 ``` ---