ENS160+AHT21 Carbon Dioxide CO2 eCO2 TVOC Air Quality & Temperature Humidity Sensor Module I2C

Specifications

• Gas Sensor Core:  ENS160 (MOX based Multi-pixel gas sensor)

• Environmental Sensor Core: AHT21 (Temperature & Humidity)

• Interface: I2C (Standard 0x53 address for ENS160)

• Output Data (ENS160): Total Volatile Organic Compounds (TVOC), equivalent CO2 (eCO2), Air Quality Index (AQI 1-5)

• Measurement Range (CO2): 400 – 65000ppm (equivalent)

• Measurement Range (TVOC): 0 – 65000ppb

• Temperature Accuracy: ±0.3°C (AHT21)

• Humidity Accuracy: ±2% RH (AHT21)

• Supply Voltage: 3.3V DC (Recommended for Logic Stability)

• Preheat Time: < 3 minutes (Superior to 20+ mins on older sensors)

Key Applications

• Smart Home Automation: Trigger ventilation fans automatically when CO2 levels rise in bedrooms or offices.

• HVAC Monitoring: Verify the efficiency of air purifiers and filters in real-time.

• IoT Weather Stations: Add pollution metrics to your ESP32 cloud dashboard.

• Industrial Safety: Monitor solvent vapours (VOCs) in 3D printing enclosures or soldering stations.

Project Evolution

• Past Projects (Prerequisites): If you have mastered the basic DHT11/DHT22 temperature setup, you are ready for this upgrade.

• Feature Upgrade: This module moves you from "Passive Observation" to "Active Health Monitoring." It allows your code to distinguish between "stuffy air" (high CO2) and "toxic air" (high VOCs from paints/cleaners).

• Effort Level: Intermediate. Requires handling I2C addresses and installing two separate libraries.

• Hardware Needed: Any microcontroller with I2C (Arduino Uno, ESP8266, ESP32, Raspberry Pi).

Virtual Technician & Wiring Guide

⚠ CRITICAL WARNING: This module operates best at 3.3V Logic. If using with a 5V Arduino Uno, we strongly recommend using a Logic Level Converter to protect the sensitive MEMS structures inside the sensor. We guarantee this device is Probots™ Logic-Safe ⚡ when used with 3.3V controllers like the ESP32 or Raspberry Pi.

Pinout Mapping:

• VCC: Connect to 3.3V

• GND: Connect to Common Ground

• SCL: Connect to I2C Clock (A5 on Uno, D22 on ESP32)

• SDA: Connect to I2C Data (A4 on Uno, D21 on ESP32)

Accessories Included:

• 1x ENS160+AHT21 Sensor Module

• 1x 4-Pin Header Strip (Unsoldered)

Required (Sold Separately):

• Microcontroller: ESP32 or Arduino

• Connection: Jumper Wires (Female-to-Female for header pins)

• Logic Level Converter: (If using 5V Arduino)

Helpful Tutorials & Resources

• ENS160 Sensor_Datasheet
  

Frequently Asked Questions (Technical FAQs)

• What is the difference between ENS160 and CCS811? The ENS160 is the successor to the CCS811, offering faster warm-up times, better immunity to humidity interference, and longer lifespan.
• Does this measure actual CO2? No, it provides "equivalent CO2" (eCO2) derived from measuring Hydrogen and VOCs, which correlates highly with human-generated CO2 in indoor spaces.
• Can I use the AHT21 and ENS160 simultaneously? Yes, they share the same I2C bus but have different addresses, so you can read both sequentially in your loop.
• What is the I2C address for the ENS160? The default I2C address is typically 0x53 (or 0x52 depending on the ADDR pin state).
• Does this sensor require burn-in time? For first-time use, run it for 24 hours to stabilize the heater. For daily use, it warms up in under 3 minutes.
• Is it compatible with Raspberry Pi? Yes, it works perfectly with Raspberry Pi via the I2C GPIO pins (3.3V logic).
• What library should I use for Arduino? We recommend the "ScioSense_ENS160" library or the Adafruit ENS160 library for best compatibility.
• Why are my TVOC readings 0? The sensor returns 0 until it has completed its initial heating cycle (approx. 3 minutes) or if the air is extremely clean.
• Can I use this outdoors? It is designed for indoor air quality. Outdoor strong winds and pollution extremes may saturate the MOX element quickly.
• Does the module have pull-up resistors? Yes, most modules include 4.7kΩ or 10kΩ pull-up resistors on the I2C lines.
• What is the operating voltage range? The chip runs on 1.71V to 1.98V, but the module includes an LDO regulator accepting 3.3V. Avoid 5V on data pins.
• Can it detect gas leaks like Methane? It is sensitive to VOCs and Hydrogen but is not a dedicated safety device for explosive gas leak detection (use MQ series for that).
• How do I calibrate the sensor? The ENS160 has automatic baseline correction. Expose it to fresh outdoor air once a week for self-calibration.
• Is the AHT21 waterproof? No, the sensor has a PTFE membrane to protect against dust, but liquid water will damage the sensor.
• Can I use this with ESPHome? Yes, ESPHome has native support for both the AHT10/20/21 and the ENS160 components.
• What is the refresh rate? The ENS160 can update data every second, though for air quality, reading every 10-60 seconds is sufficient.
• Does soldering the headers damage the sensor? Excessive heat can shift the AHT21 readings. Solder quickly and keep the iron away from the sensor chip body.
• Why is the eCO2 reading 400ppm constantly? 400ppm is the baseline (fresh air). If it stays there, the sensor may still be warming up or the baseline was reset incorrectly.
• Does it measure PM2.5 dust? No, this measures gases. For particulate matter (dust/smoke), you need a PM sensor like the PMS5003.
• Can I change the I2C address? Some board layouts break out the ADDR pin; pulling it high or low can toggle the address between 0x52 and 0x53.