AHT20 + BMP280 Sensor Module Documentation

1. Introduction

The AHT20 + BMP280 Sensor Module is a versatile and compact environmental sensing solution that combines two powerful sensors in a single module. The AHT20 is a high-precision temperature and humidity sensor, while the BMP280 is a barometric pressure and temperature sensor. Together, they provide accurate measurements of temperature, humidity, and atmospheric pressure, making this module ideal for a wide range of applications.

Common Applications:

• Weather monitoring systems
• IoT (Internet of Things) devices
• Environmental data logging
• HVAC (Heating, Ventilation, and Air Conditioning) systems
• Altitude measurement for drones and other devices
• Smart home automation

2. Technical Specifications

AHT20 Sensor Specifications:

BMP280 Sensor Specifications:

Pin Configuration:

3. Usage Instructions

Connecting the AHT20 + BMP280 to an Arduino UNO:

1. Wiring:

   • Connect the module's VCC pin to the Arduino's 5V pin.
   • Connect the GND pin to the Arduino's GND.
   • Connect the SDA pin to the Arduino's A4 pin (I²C data line).
   • Connect the SCL pin to the Arduino's A5 pin (I²C clock line).

2. Install Required Libraries:

   • Install the Adafruit_AHTX0 library for the AHT20 sensor.
   • Install the Adafruit_BMP280 library for the BMP280 sensor.
   • These libraries can be installed via the Arduino IDE Library Manager.

3. Arduino Code Example: Below is an example code to read temperature, humidity, and pressure data from the AHT20 and BMP280 sensors.

#include <Wire.h>
#include <Adafruit_AHTX0.h> // Library for AHT20
#include <Adafruit_BMP280.h> // Library for BMP280

// Create sensor objects
Adafruit_AHTX0 aht;
Adafruit_BMP280 bmp;

void setup() {
  Serial.begin(9600);
  while (!Serial); // Wait for Serial Monitor to open

  // Initialize AHT20 sensor
  if (!aht.begin()) {
    Serial.println("Failed to initialize AHT20 sensor!");
    while (1);
  }
  Serial.println("AHT20 sensor initialized.");

  // Initialize BMP280 sensor
  if (!bmp.begin(0x76)) { // Default I²C address for BMP280 is 0x76
    Serial.println("Failed to initialize BMP280 sensor!");
    while (1);
  }
  Serial.println("BMP280 sensor initialized.");
}

void loop() {
  // Read data from AHT20
  sensors_event_t humidity, temp;
  aht.getEvent(&humidity, &temp);

  // Read data from BMP280
  float pressure = bmp.readPressure() / 100.0F; // Convert to hPa
  float altitude = bmp.readAltitude(1013.25); // Sea level pressure in hPa

  // Print sensor data to Serial Monitor
  Serial.print("AHT20 - Temperature: ");
  Serial.print(temp.temperature);
  Serial.print(" °C, Humidity: ");
  Serial.print(humidity.relative_humidity);
  Serial.println(" %");

  Serial.print("BMP280 - Pressure: ");
  Serial.print(pressure);
  Serial.print(" hPa, Altitude: ");
  Serial.print(altitude);
  Serial.println(" m");

  delay(2000); // Wait 2 seconds before next reading
}

Important Considerations:

• Ensure the I²C address of the BMP280 sensor matches the one in the code (default is 0x76).
• Use appropriate pull-up resistors (typically 4.7kΩ) on the SDA and SCL lines if not already included on the module.
• Avoid exposing the sensors to extreme conditions (e.g., high humidity or temperature) for prolonged periods to maintain accuracy.

4. Troubleshooting and FAQs

Common Issues and Solutions:

1. Issue: The sensors are not detected by the Arduino.

   • Solution: Check the wiring and ensure the SDA and SCL lines are connected correctly. Verify the I²C addresses in the code.

2. Issue: Incorrect or fluctuating readings.

   • Solution: Ensure the module is not exposed to electrical noise or unstable power supply. Use a decoupling capacitor (e.g., 0.1µF) across the VCC and GND pins.

3. Issue: BMP280 altitude readings are inaccurate.

   • Solution: Update the sea level pressure value in the code (1013.25 hPa by default) to match the current atmospheric pressure at your location.

FAQs:

Q1: Can I use this module with a 3.3V microcontroller?
A1: Yes, the module supports both 3.3V and 5V logic levels. Ensure the power supply matches your microcontroller's voltage.

Q2: What is the maximum I²C bus speed supported?
A2: The sensors support standard (100 kHz) and fast (400 kHz) I²C speeds.

Q3: Can I use SPI communication for the BMP280?
A3: Yes, the BMP280 supports SPI, but this module is typically configured for I²C communication.

This documentation provides a comprehensive guide to using the AHT20 + BMP280 sensor module. Whether you're a beginner or an experienced user, this guide will help you integrate the module into your projects with ease.