How to Use Adafruit HTS221: Examples, Pinouts, and Specs

The Adafruit HTS221 is a high-precision sensor module designed for acquiring environmental data by measuring both temperature and humidity. Its compact form factor and low power consumption make it an ideal choice for a variety of applications, including weather stations, home automation systems, and IoT devices. The sensor communicates over the I2C interface, allowing for easy integration with microcontrollers such as the Arduino UNO.

• Relative Humidity Range: 0 to 100%
• Temperature Range: -40°C to +120°C
• Humidity Accuracy: ± 3.5% RH (20 to +80% RH)
• Temperature Accuracy: ± 0.5°C (15 to +40°C)
• Communication Interface: I2C
• Supply Voltage: 1.7V to 3.6V
• Average Current Consumption: 2µA (humidity and temperature in low-power mode)

1. Connecting the Sensor:

   • Connect VDD to the 3.3V output on the Arduino UNO.
   • Connect GND to one of the GND pins on the Arduino UNO.
   • Connect SDA to the A4 pin (SDA) on the Arduino UNO.
   • Connect SCL to the A5 pin (SCL) on the Arduino UNO.
   • The DRDY pin can be left unconnected if not used.

2. Library Installation:

   • Install the Adafruit HTS221 library using the Arduino Library Manager or download it from the Adafruit GitHub repository.

3. Sample Code:

   #include <Wire.h>
   #include <Adafruit_Sensor.h>
   #include <Adafruit_HTS221.h>
   
   Adafruit_HTS221 hts;
   
   void setup() {
     Serial.begin(9600);
     // Wait for serial monitor to open
     while (!Serial) { delay(10); }
   
     Serial.println("Adafruit HTS221 test!");
   
     if (!hts.begin()) {
       Serial.println("Failed to find HTS221 chip");
       while (1) { delay(10); }
     }
     Serial.println("HTS221 Found!");
   }
   
   void loop() {
     sensors_event_t humidity, temp;
     hts.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);
   }
   

   • Ensure that the code comments do not exceed 80 characters per line.

• Always use a logic level converter if you are interfacing the HTS221 with a 5V microcontroller to avoid damaging the sensor.
• Place the sensor away from heat-generating components to prevent false readings.
• For accurate measurements, allow the sensor to acclimatize to the environment before taking readings.
• Avoid touching the sensor element directly as it may affect the readings.

• Sensor Not Detected: Ensure that the wiring is correct and that the sensor is properly powered. Check the I2C address and connections.
• Inaccurate Readings: Make sure the sensor is not placed near heat sources or in direct sunlight. Allow it to acclimatize to the environment.

Q: Can the HTS221 be used with a 5V microcontroller? A: Yes, but a logic level converter is required to shift the I2C signals to 3.3V.

Q: How can I calibrate the sensor? A: The HTS221 comes factory-calibrated. If further calibration is needed, refer to the sensor's datasheet for calibration procedures.

Q: Is the HTS221 waterproof? A: No, the HTS221 is not waterproof. Protect it from moisture and condensation.

For further assistance, consult the Adafruit HTS221 datasheet and the Adafruit support forums.