The **JQ300-R** is a specialized sensor module primarily used for **Air Quality Monitoring**. It is designed to detect multiple environmental parameters and output data via serial communication, making it popular for DIY projects (Arduino/ESP32) and industrial air purifiers. --- ## 1. Core Technical Specifications The JQ300-R is an integrated "all-in-one" sensor. Below are the primary electronic characteristics: | Parameter | Specification | | :--- | :--- | | **Operating Voltage** | DC 5V (±0.2V) | | **Operating Current** | < 100mA | | **Interface Type** | UART (TTL Level @ 3.3V) | | **Warm-up Time** | 3 - 5 minutes for stable readings | | **Output Baud Rate** | 9600 bps | | **Dimensions** | Approx. 35mm x 22mm | --- ## 2. Sensor Capabilities (Measurement Range) The module integrates several sensing elements to provide a comprehensive air quality profile: 1. **TVOC (Total Volatile Organic Compounds):** 0 – 9.999 mg/m³ 2. **eCO2 (Equivalent CO2):** 400 – 5000 ppm (Calculated based on VOC levels) 3. **HCHO (Formaldehyde):** 0 – 1.999 mg/m³ 4. **Temperature:** 0 – 50°C 5. **Humidity:** 0 – 99% RH --- ## 3. Pinout Configuration The JQ300-R typically uses a 4-pin or 5-pin connector. The standard wiring is as follows: | Pin | Label | Description | | :--- | :--- | :--- | | 1 | **VCC** | 5V Power Supply | | 2 | **GND** | Ground | | 3 | **TX** | Transmit Data (Connect to MCU RX) | | 4 | **RX** | Receive Data (Connect to MCU TX) | --- ## 4. Communication Protocol The module outputs a data packet automatically every second via the UART interface. The data is usually sent in a Hexadecimal format. ### Example Data Frame Structure: A typical frame consists of a header, the data bytes, and a checksum. ```text Header: 0x2C Byte 1-2: Formaldehyde (HCHO) Byte 3-4: TVOC Byte 5-6: eCO2 Byte 7-8: Temperature Byte 9-10: Humidity Checksum: (Sum of previous bytes) & 0xFF ``` --- ## 5. Integration Implementation (Arduino Example) To read data from the JQ300-R, you use the Hardware or Software Serial library. ```cpp #include // RX on D2, TX on D3 SoftwareSerial jqSerial(2, 3); void setup() { Serial.begin(9600); jqSerial.begin(9600); Serial.println("JQ300-R Initializing..."); } void loop() { if (jqSerial.available() > 0) { byte data = jqSerial.read(); // Logic to parse the Hex frame goes here Serial.print(data, HEX); Serial.print(" "); } } ``` --- ## 6. Usage Considerations * **Calibration:** The eCO2 reading is an estimate based on VOCs, not a true NDIR (Non-Dispersive Infrared) measurement. For safety-critical CO2 monitoring, an NDIR sensor is preferred. * **Environment:** Avoid exposing the sensor to high concentrations of corrosive gases or silicone vapors, which can poison the chemical sensing elements. * **Burn-in:** New modules may require a "burn-in" period of 24-48 hours of continuous operation to achieve maximum accuracy.