AHT20 Integrated temperature and humidity Sensor and ESP32 board example

ESP32 and AHT20
ESP32 and AHT20

Another day another sensor hits the workshop.

In this example we connect a AHT20 Integrated temperature and humidity Sensor to an ESP32

First lets look at some information about the sensor from the manufacturer

AHT20, as a new generation of temperature and humidity sensors, has established a new standard in size and intelligence. It is embedded in a double row flat no-lead package suitable for reflow soldering, with a bottom of 3 x 3 mm and a height of 1.0 mm.

The sensor outputs calibrated digital signals in standard IAHT20, as a new generation of temperature and humidity sensors, has established a new standard in size and intelligence.

It is embedded in a double row flat no-lead package suitable for reflow soldering, with a bottom of 3 x 3 mm and a height of 1.0 mm.

The sensor outputs calibrated digital signals in standard I2C format. The AHT20 is equipped with a newly designed ASIC chip, an improved MEMS semiconductor capacitive humidity sensing element and a standard on-chip temperature sensing element.

Supply voltage DC : 2.0 – 5.5V
Measuring range (humidity) 0 ~ 100% RH
Measuring range (temperature) -40 ~ + 85 ℃
Humidity accuracy ± 2 % RH ( 25 ℃ )
Temperature accuracy ± 0.3 ℃
Resolution temperature: 0.01℃ Humidity: 0.024%RH
Response time temperature: 5s humidity: 8s 1/e (63%)
Output signal I2C signal

 

This is the sensor that I bought

 

Parts Required

Here are the parts I used

The sensor you can pick up in the $6 price range – you can connect to the sensor using a standard header the classic dupont style jumper wire.

Name Link
ESP32 WeMos Mini D1 LOLIN32 ESP32
AHT20  

AHT20 Temperature and Humidity Sensor Module High-precision Humidity Sensor

Connecting wire Free shipping Dupont line 120pcs 20cm male to male + male to female and female to female jumper wire

 

Schematic/Connection

The layout below shows an Adafruit Huzzah ESP32, I tried a couple of other ESP32 boards like the Lolin32 as well and they worked just fine

If you have an ESP32 board with a STEMMA QT cables, you can use these:

Black for GND
Red for V+
Blue for SDA
Yellow for SCL

I actually just extended and use this but in the layout I have shown that you can solder a header and just this as well – so you have a choice

ESP32 and AHT20
ESP32 and AHT20

Code Example

This example uses a couple of libraries, both of which can be installed using the library manager. if you search for the AHT20 one first and you are using a newer version of the Arduino IDE it will install the other one as well – which makes things a bit easier.

You need the Adafruit library for the AHT20 from https://github.com/adafruit/Adafruit_AHTX0

You also need an I2C support library from the same folks for the library above to work and that is available from – https://github.com/adafruit/Adafruit_BusIO

This is the simple test example that comes with the library

#include <Adafruit_AHTX0.h>
 
Adafruit_AHTX0 aht;
 
void setup() 
{
  Serial.begin(115200);
  Serial.println("Adafruit AHT10/AHT20 demo!");
 
  if (! aht.begin()) 
  {
    Serial.println("Could not find AHT? Check wiring");
    while (1) delay(10);
  }
  Serial.println("AHT10 or AHT20 found");
}
 
void loop() {
  sensors_event_t humidity, temp;
  aht.getEvent(&humidity, &temp);// populate temp and humidity objects with fresh data
  Serial.print("Temperature: "); 
  Serial.print(temp.temperature); 
  Serial.println(" degrees C");
  Serial.print("Humidity: "); 
  Serial.print(humidity.relative_humidity); 
  Serial.println("% rH");
 
  delay(500);
}

Output

Here is what I saw in Serial monitor

Temperature: 21.42 degrees C
Humidity: 52.41% rH
Temperature: 21.72 degrees C
Humidity: 54.38% rH
Temperature: 21.91 degrees C
Humidity: 56.12% rH
Temperature: 21.90 degrees C
Humidity: 57.22% rH
Temperature: 21.61 degrees C
Humidity: 56.53% rH

Links

Product download pdf

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