How to Use ENS160+AHT21: Examples, Pinouts, and Specs

The ENS160 is a digital metal-oxide (MOX) gas sensor designed for air quality monitoring. It provides accurate measurements of volatile organic compounds (VOCs) and equivalent CO2 (eCO2) levels. The AHT21, on the other hand, is a high-precision temperature and humidity sensor. When combined, the ENS160 and AHT21 form a powerful duo for environmental sensing, enabling applications such as indoor air quality monitoring, HVAC systems, and IoT-based environmental monitoring.

• Indoor air quality monitoring
• Smart home automation
• HVAC systems
• IoT environmental sensing
• Industrial air quality control

1. Wiring: Connect the ENS160 and AHT21 to the Arduino UNO as follows:

   • ENS160:
     • VDD to 3.3V on Arduino
     • GND to GND on Arduino
     • SDA to A4 (I²C data line)
     • SCL to A5 (I²C clock line)
   • AHT21:
     • VDD to 5V on Arduino
     • GND to GND on Arduino
     • SDA to A4 (shared with ENS160)
     • SCL to A5 (shared with ENS160)

2. Install Libraries:

   • Install the Adafruit_Sensor and Adafruit_AHTX0 libraries for the AHT21.
   • Install the ENS160 library (if available) or use a custom I²C communication library.

3. Arduino Code: Below is an example code snippet to read data from both sensors:

   #include <Wire.h>
   #include <Adafruit_AHTX0.h> // Library for AHT21
   #include <ENS160.h>         // Library for ENS160 (replace with actual library)
   
   Adafruit_AHTX0 aht; // Create AHT21 object
   ENS160 ens160;      // Create ENS160 object
   
   void setup() {
     Serial.begin(9600);
     Wire.begin();
   
     // Initialize AHT21
     if (!aht.begin()) {
       Serial.println("Failed to initialize AHT21!");
       while (1);
     }
     Serial.println("AHT21 initialized.");
   
     // Initialize ENS160
     if (!ens160.begin()) {
       Serial.println("Failed to initialize ENS160!");
       while (1);
     }
     Serial.println("ENS160 initialized.");
   }
   
   void loop() {
     // Read temperature and humidity from AHT21
     sensors_event_t humidity, temp;
     aht.getEvent(&humidity, &temp);
     Serial.print("Temperature: ");
     Serial.print(temp.temperature);
     Serial.println(" °C");
     Serial.print("Humidity: ");
     Serial.print(humidity.relative_humidity);
     Serial.println(" %");
   
     // Read air quality data from ENS160
     uint16_t voc = ens160.getVOC();
     uint16_t eco2 = ens160.getECO2();
     Serial.print("VOC: ");
     Serial.print(voc);
     Serial.println(" (arbitrary units)");
     Serial.print("eCO2: ");
     Serial.print(eco2);
     Serial.println(" ppm");
   
     delay(2000); // Wait 2 seconds before next reading
   }
   

• Ensure proper voltage levels for each sensor. Use level shifters if necessary.
• Keep the sensors away from direct heat sources or contaminants for accurate readings.
• Calibrate the ENS160 for optimal VOC and eCO2 measurements in your specific environment.

1. Sensors not detected on I²C bus:

   • Ensure correct wiring and check for loose connections.
   • Verify the I²C addresses of the sensors (default: ENS160 - 0x53, AHT21 - 0x38).

2. Inaccurate readings:

   • Allow the sensors to stabilize for a few minutes after powering on.
   • Avoid placing the sensors in areas with extreme temperatures or humidity.

3. Arduino code not compiling:

   • Ensure all required libraries are installed and up to date.
   • Check for typos in the code or library function calls.

Q: Can I use both sensors on the same I²C bus?
A: Yes, the ENS160 and AHT21 have different I²C addresses, so they can share the same bus.

Q: How do I calibrate the ENS160?
A: The ENS160 automatically calibrates itself over time. For best results, expose it to clean air periodically.

Q: What is the typical response time of the sensors?
A: The AHT21 has a response time of approximately 8 seconds for humidity and temperature. The ENS160 typically updates VOC and eCO2 values every second.