lamaPLC: ENS160 + AHT21 Air Quality Sensor - CO, ECO, TVOC, Temp & Humidity Module

The ENS160 + AHT21 Air Quality Module is a combined environmental sensor board that measures indoor air pollutants (VOCs, eCO₂, AQI) and climate conditions (Temperature, Humidity). It is a popular upgrade for older sensors like the CCS811 due to its integrated sensor fusion and automatic calibration.

• Detection of reducing (VOC) and oxidizing gases (such as NO₂)
• MOX supports up to 4 gas sensors
• Integrated sensor measurement and heater drive control
• Integrated pre-calibrated sensor fusion and automatic correction algorithm

Key Capabilities

• ENS160 (Air Quality): Uses Metal-Oxide (MOX) technology to detect reducing and oxidizing gases.
  • Outputs: Total Volatile Organic Compounds (TVOC), equivalent CO₂ (eCO₂) ), and Air Quality Index (AQI).
  • Target Gases: Ethanol, toluene, hydrogen, NO₂, and ozone.
• AHT21 (Climate): A high-precision digital temperature and humidity sensor.
  • Temperature: ±0.3 °C accuracy; range of -40 °C to +120 °C.
  • Humidity: ±2 % RH accuracy; range of 0 to 100 % RH.

Technical Specifications

To use the ENS160 + AHT21 module with Arduino, you'll typically need two libraries from the Arduino Library Manager: Adafruit ENS160 and Adafruit AHTX0.

Install Required Libraries

Open the Arduino IDE and install the following:

• Adafruit ENS160 Library
• Adafruit AHTX0 Library (works for both AHT20 and AHT21)
• Adafruit Unified Sensor (dependency for many Adafruit libraries)

This code initializes both sensors via I²C and prints climate and air quality data to the Serial Monitor every two seconds.

#include <Wire.h>
#include <Adafruit_ENS160.h>
#include <Adafruit_AHTX0.h>
 
Adafruit_ENS160 ens160;
Adafruit_AHTX0 aht;
 
void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10); // Wait for Serial Monitor
 
  Serial.println("ENS160 + AHT21 Test");
 
  // Initialize AHT21 (Address 0x38)
  if (!aht.begin()) {
    Serial.println("Could not find AHT21 sensor!");
    while (1) delay(10);
  }
  Serial.println("AHT21 initialized.");
 
  // Initialize ENS160 (Address 0x53 or 0x52)
  // Most combo boards default to 0x53
  if (!ens160.begin(0x53)) {
    Serial.println("Could not find ENS160 sensor!");
    while (1) delay(10);
  }
 
  // Set operating mode: Standard (detecting)
  ens160.setMode(ENS160_OPMODE_STD);
  Serial.println("ENS160 initialized.");
}
 
void loop() {
  // 1. Read Climate Data from AHT21
  sensors_event_t humidity, temp;
  aht.getEvent(&humidity, &temp);
 
  // 2. Feed Temperature/Humidity to ENS160 for better accuracy
  ens160.setTempRH(temp.temperature, humidity.relative_humidity);
 
  // 3. Read Air Quality Data from ENS160
  if (ens160.available()) {
    Serial.print("Temp: "); Serial.print(temp.temperature); Serial.println(" C");
    Serial.print("Humidity: "); Serial.print(humidity.relative_humidity); Serial.println(" %");
 
    Serial.print("AQI: "); Serial.println(ens160.getAQI());
    Serial.print("TVOC: "); Serial.print(ens160.getTVOC()); Serial.println(" ppb");
    Serial.print("eCO2: "); Serial.print(ens160.getECO2()); Serial.println(" ppm");
    Serial.println("-----------------------");
  }
 
  delay(2000);
}

Usage Tips

• Baud Rate: Set your Serial Monitor to 115200 to match the code above.
• Warm-up: The ENS160 requires about 1 hour to achieve full accuracy, though it will start providing initial readings within 1 minute.
• Address Conflict: If the ENS160 is not found, try changing ens160.begin(0x53) to ens160.begin(0x52).
• Library Alternatives: If the Adafruit library doesn't work for your specific breakout, the DFRobot_ENS160 library is a highly compatible alternative.

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