BMP180 Temperature and Barometric Pressure Sensor for Arduino

BMP180 Temperature and Barometric Pressure Sensor for Arduino

The BMP180 sensor is a versatile device that measures temperature and barometric pressure, making it ideal for various applications such as weather monitoring and altitude measurement. In this tutorial, we will connect the BMP180 sensor to an Arduino, read temperature and pressure data, and display the results. By the end of this project, you will be able to obtain accurate temperature readings in Celsius and Fahrenheit, as well as pressure values in millibars and inches of mercury.

To clarify the concepts and coding steps, I encourage you to watch the associated video for detailed explanations (in video at 00:00).

Hardware Explained

The BMP180 is a digital sensor that communicates via I2C, which allows it to interface easily with microcontrollers like Arduino. It has four pins: Vn (power supply), GND (ground), SDA (data line), and SCL (clock line). The sensor operates within a voltage range of 1.8 to 3.6 volts, but it can be powered by a regulated 5V supply using a voltage regulator.

This sensor's ability to measure atmospheric pressure makes it suitable for applications that require altitude estimation and weather monitoring. The BMP180 also includes a built-in temperature sensor, which is essential for obtaining accurate pressure readings. By measuring temperature first, the sensor can compensate for temperature variances that affect pressure readings.

Datasheet Details

Manufacturer	Bosch
Part number	BMP180
Logic/IO voltage	1.8 - 3.6 V
Supply voltage	1.8 - 5.0 V
Output current (typ.)	5 μA
Peak current (max.)	1 mA
PWM frequency guidance	N/A
Input logic thresholds	N/A
Voltage drop / R_DS(on) / saturation	N/A
Thermal limits	-40 to 85 °C
Package	3.6 x 3.8 mm
Notes / variants	Low power consumption

Ensure proper voltage levels to avoid damaging the sensor.
Use pull-up resistors on the I2C lines if necessary.
Keep the sensor in a stable temperature environment for accurate readings.
Calibrate the altitude based on your specific location for precise results.
Monitor the power supply to ensure it remains within specified limits.

Wiring Instructions

Arduino wiring for BMP180 Temperature sensor

To wire the BMP180 sensor to your Arduino, start by connecting the Vn pin of the BMP180 to the 5V pin on the Arduino. Next, connect the GND pin to the Arduino's ground. For the I2C communication, connect the SDA pin to the Arduino's analog pin A4 and the SCL pin to A5. Make sure your connections are secure to prevent any communication issues.

If you're using a different Arduino model, be aware that the I2C pins may vary. For example, on a Mega2560, the SDA and SCL pins are 20 and 21, respectively. Always double-check the pin mapping for your specific board to ensure proper functionality.

Code Examples & Walkthrough

#include 
#include 

SFE_BMP180 pressure;
#define ALTITUDE 90.0 // Altitude of Robojax Headquarter

In the code, we start by including the necessary libraries: SFE_BMP180.h for the sensor and Wire.h for I2C communication. We create an instance of the BMP180 object named pressure and define the altitude at which our readings will be taken using the ALTITUDE constant.

void setup() {
  Serial.begin(9600);
  if (pressure.begin()) Serial.println("BMP180 init success");
  else { Serial.println("BMP180 init fail\n\n"); while(1); }
}

The setup function initializes the serial communication at 9600 baud and attempts to start the BMP180 sensor. If the initialization fails, the program enters an infinite loop to halt further execution, indicating a connection problem.

void loop() {
  char status;
  double T, P, p0, a;

  status = pressure.startTemperature();
  if (status != 0) {
    delay(status);
    status = pressure.getTemperature(T);
    if (status != 0) {
      Serial.print("temperature: "); Serial.print(T,2);
    }
  }
}

In the loop function, we first initiate a temperature reading by calling startTemperature(). If successful, we wait for the measurement to complete and retrieve the temperature with getTemperature(T), where T stores the temperature value. The temperature is then printed to the serial monitor.

Demonstration / What to Expect

When powered and correctly wired, the BMP180 will continuously read and display the temperature and pressure data every five seconds. You should see the temperature values in both Celsius and Fahrenheit, as well as the absolute and relative pressure values. If the sensor is functioning correctly, you will receive readings without errors. Be aware of potential pitfalls like incorrect voltage levels or loose connections, which can lead to failure in obtaining data.