Introduction

The AHT20 is a high-precision but low-cost temperature and humidity sensor, which is equipped with an improved MEMS semiconductor capacitive humidity sensor element. It features standard I2C interface and a wide voltage supply of 2V - 5V. And with simple peripheral circuit, it performs stably even in harsh environments in the measuring range of -40 - ＋85℃.

This sensor can be widely used for measuring the environmental temperature and humidity of home electronic equipment, the temperature and humidity of automobiles and so on.

Features

  • Digital output, I2C interface
  • Excellent long-term stability
  • Quick response, strong anti-interference ability and strong ability to adapt to the environment
  • Gravity interface, simple wiring, no soldering required

Applications

  • Testing Equipment
  • Automatic Control
  • Data Loggers
  • Weather Control

Specification

Module Parameters

  • Operating Voltage: DC2V~5V
  • Operating Current: 0.27mA (at 3.3V)
  • Communication Protocol: I2C
  • I2C Address: 0x38
  • Dimension: 30mm×20.5mm/1.18×0.81"

AHT20 Chip Parameters

Relative Humidity

  • Resolution: 0.024 %RH
  • Accuracy: ±2 %RH
  • Repeatability: ±0.1 %RH
  • Hysteresis: ±1 %RH
  • Non-linear: ±0.1 %RH
  • Response Time: 8S
  • Operating Range: 0~100 %RH
  • Long-term Drift: ＜0.5 %RH/yr

Temperature

  • Resolution: 0.01℃
  • Accuracy Error: ±0.3℃
  • Repeatability: ±0.1℃
  • Hysteresis: ±0.1℃
  • Response Time: minimum 5S, maximum 30S
  • Operating Range: -40℃~85℃
  • Long-term Drift: <0.04℃/yr

Dimension Diagram

Pinout

Pin Function Description
+ Positive Power Supply Power Supply: DC 2V~5V
- Negative Power Supply --
SCL I2C Clock Line --
SDA I2C Data Line --

Tutorial

AHT20 Temperature and Humidity Sensor Reading Test

Hardware Requirement

  • DFRduino UNO R3 (or similar) x 1
  • SEN0528 Gravity: AHT20 Temperature and Humidity Sensor x 1
  • M-M/F-M/F-F Jumper wires

Software Requirement

Connection Diagram

UNO Board: 3V3 - connect to - AHT20:+

UNO Board: GND - connect to - AHT20:-

UNO Board: SCL - connect to - AHT20:C

UNO Board: SDA - connect to - AHT20:D

Sample Code

The following code will read the measured values from the AHT20 temperature and humidity sensor and print them through the serial port.

    #include "DFRobot_AHT20.h"
    DFRobot_AHT20 aht20;
    void setup(){
      Serial.begin(115200);
      while(!Serial){
      }
      uint8_t status;
      while((status = aht20.begin()) != 0){
        Serial.print("AHT20 sensor initialization failed. error status : ");
        Serial.println(status);
        delay(1000);
      }
    }
    void loop(){
      if(aht20.startMeasurementReady(true)){
        Serial.print("temperature(-40~85 C): ");
        Serial.print(aht20.getTemperature_C());
        Serial.print(" C, ");
        Serial.print(aht20.getTemperature_F());
        Serial.print(" F\t");
        Serial.print("humidity(0~100): ");
        Serial.print(aht20.getHumidity_RH());
        Serial.println(" %RH");
        delay(8000);
      }
    }

Test Process

The results are as shown in the figure below, the temperature values in ℃ and ℉, and humidity values are displayed in the serial monitor.

Library Function Definition

 /**
   * @fn DFRobot_AHT20
   * @brief DFRobot_AHT20 constructor
   * @param wire TwoWire class object reference
   * @return NONE
   */
  DFRobot_AHT20(TwoWire &wire = Wire);
  /**
   * @fn begin
   * @brief Initialize AHT20 sensor
   * @return Init status value
   * @retval  0    Init succeeded
   * @retval  1    _pWire is NULL, please check if the constructor DFRobot_AHT20 has correctly uploaded a TwoWire class object reference
   * @retval  2    Device is not found, please check if the connection is correct
   * @retval  3    If the sensor init fails, please check if there is any problem with the sensor, you can call the reset function and re-initialize after restoring the sensor
   */
  uint8_t begin();
  /**
   * @fn reset
   * @brief Sensor soft reset, restore the sensor to the initial status.
   * @return NONE
   */
  void reset();
  /**
   * @fn startMeasurementReady
   * @brief Start measurement and determine if it’s completed.
   * @param crcEn Whether to enable check during measurement
   * @n     false  Measure without check (by default)
   * @n     true   Measure with check
   * @return Whether the measurement is done
   * @retval true  If the measurement is completed, call a related function such as get* to obtain the measured data.
   * @retval false If the measurement failed, the obtained data is the data of last measurement or the initial value 0 if the related function such as get* is called at this time.
   */
  bool startMeasurementReady(bool crcEn = false);
  /**
   * @fn getTemperature_F
   * @brief Get ambient temperature, unit: Fahrenheit (F).
   * @return Temperature in F
   * @note  AHT20 can't directly get the temp in F, the temp in F is calculated according to the algorithm: F = C x 1.8 + 32
   * @n Users must call the startMeasurementReady function once to start the measurement before calling this function so as to get the real-time measured data,
   * @n otherwise what they obtained is the initial data or the data of last measurement.
   */
  float getTemperature_F();
  /**
   * @fn getTemperature_C
   * @brief Get ambient temperature, unit: Celsius (℃).
   * @return Temperature in ℃, it's normal data within the range of -40-85℃, otherwise it's wrong data
   * @note Users must call the startMeasurementReady function once to start the measurement before calling this function so as to get the real-time measured data,
   * @n otherwise what they obtained is the initial data or the data of last measurement.
   */
  float getTemperature_C();
  /**
   * @fn getHumidity_RH
   * @brief Get ambient relative humidity, unit: %RH.
   * @return Relative humidity, range 0-100
   * @note Users must call the startMeasurementReady function once to start the measurement before calling this function so as to get the real-time measured data,
   * @n otherwise what they obtained is the initial data or the data of last measurement
   */
  float getHumidity_RH();

More Documents

SEN0528 Dimensions

SEN0528-Circuit Diagram SCH.pdf

SEN0528_2D_Dimensions.pdf

SEN0528_2D-CAD_Dimensions.rar

SEN0528_3D_STP.rar

FAQ

For any questions, advice or cool ideas to share, please visit the DFRobot Forum.

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