How to Use Adafruit PCT2075: Examples, Pinouts, and Specs

The Adafruit PCT2075 is a digital temperature sensor module that offers high-accuracy temperature measurements using I2C communication. This sensor is based on the PCT2075 temperature sensor IC and is designed for easy integration into a wide range of electronic projects, including environmental monitoring, system temperature feedback, and IoT applications.

• Supply Voltage: 2.7V to 5.5V
• Temperature Range: -40°C to +125°C
• Accuracy: ±1°C (from -25°C to +100°C)
• Resolution: 0.1°C
• Interface: I2C
• I2C Address: Configurable, default 0x28 (up to 8 addresses selectable)
• Operating Current: 1 mA (typical)

1. Power Supply: Connect the VDD pin to a 2.7V to 5.5V power source and the GND pin to the ground.
2. I2C Communication: Connect the SDA and SCL pins to the I2C data and clock lines, respectively. Ensure pull-up resistors are in place if they are not provided by the microcontroller board.
3. Over-temperature Shutdown: The OS pin can be connected to an interrupt pin on a microcontroller to trigger an action when a set temperature threshold is exceeded.

• Use decoupling capacitors close to the sensor's power supply pins to filter out noise.
• Avoid placing the sensor near heat-generating components to prevent false readings.
• Ensure that the I2C bus has appropriate pull-up resistors, typically 4.7kΩ to 10kΩ.

#include <Wire.h>

// PCT2075 I2C address (default)
#define PCT2075_ADDRESS 0x28

// Register addresses
#define TEMP_REGISTER 0x00

void setup() {
  Wire.begin(); // Initialize I2C
  Serial.begin(9600); // Start serial communication
}

void loop() {
  Wire.beginTransmission(PCT2075_ADDRESS);
  Wire.write(TEMP_REGISTER); // Point to the temperature register
  Wire.endTransmission();

  Wire.requestFrom(PCT2075_ADDRESS, 2); // Request 2 bytes from the sensor
  if (Wire.available() == 2) {
    int tempRaw = Wire.read() << 8 | Wire.read(); // Read the temperature value
    float temperature = tempRaw / 256.0; // Convert to Celsius
    Serial.print("Temperature: ");
    Serial.print(temperature);
    Serial.println(" C");
  }

  delay(1000); // Wait for 1 second before reading again
}

• Inaccurate Temperature Readings: Ensure the sensor is not placed near heat sources and that the I2C bus is free from noise.
• No Communication: Check the wiring, ensure correct pull-up resistors are in place, and verify that the sensor's power supply is within the specified range.

• Noise Reduction: Use shielded cables for I2C lines and keep the sensor away from high-frequency signals.
• Address Conflict: Make sure no other device on the I2C bus has the same address as the PCT2075.

Q: Can I change the I2C address of the sensor? A: Yes, the PCT2075 has configurable I2C addresses. Refer to the datasheet for instructions on setting a different address.

Q: What is the maximum distance for the I2C bus? A: I2C is typically used for short distances, but with proper bus buffering and lower speeds, it can be extended. Keep the lines as short as possible for reliable communication.

Q: How do I calibrate the sensor? A: The PCT2075 is factory-calibrated. However, if you need to adjust the readings, this should be done in software by applying an offset.

Q: Is the sensor waterproof? A: No, the Adafruit PCT2075 is not waterproof. Protect it from moisture and liquids to ensure proper operation.