The BMP180 is a high-precision, low-power barometric pressure sensor that can measure atmospheric pressure and temperature. It is widely used in weather stations, altimeters, and other applications where accurate pressure measurements are essential. In the context of Raspberry Pi, the BMP180 can be a valuable addition for projects that require environmental data collection. This article will guide you on how to interface the BMP180 sensor with a Raspberry Pi, including wiring, installing necessary libraries, and running a Python script to read data from the sensor.

Examples:

Hardware Setup

1. Components Needed:

   • Raspberry Pi (any model with GPIO pins)
   • BMP180 sensor
   • Breadboard and jumper wires

2. Wiring:

   • Connect the BMP180 sensor to the Raspberry Pi as follows:
     • VCC to 3.3V (pin 1 on the Raspberry Pi)
     • GND to GND (pin 6 on the Raspberry Pi)
     • SCL to SCL (pin 5 on the Raspberry Pi)
     • SDA to SDA (pin 3 on the Raspberry Pi)

Software Setup

1. Update and Upgrade the System:

   sudo apt-get update
   sudo apt-get upgrade

2. Install Required Libraries: The BMP180 sensor communicates over the I2C protocol. Therefore, you need to enable I2C on the Raspberry Pi and install the necessary Python libraries.

   • Enable I2C:

     sudo raspi-config

     Navigate to Interfacing Options -> I2C -> Enable.

   • Install Python libraries:

     sudo apt-get install python3-smbus python3-dev
     sudo pip3 install RPi.bme280

3. Python Script to Read Data: Create a new Python script (e.g., bmp180_read.py) and add the following code:

   import smbus
   import time
   
   # BMP180 default address
   BMP180_ADDR = 0x77
   
   # Register addresses
   REG_CONTROL = 0xF4
   REG_RESULT = 0xF6
   REG_TEMP = 0x2E
   REG_PRESSURE = 0x34
   
   # Initialize I2C (SMBus)
   bus = smbus.SMBus(1)
   
   def read_raw_data(addr):
      high = bus.read_byte_data(BMP180_ADDR, addr)
      low = bus.read_byte_data(BMP180_ADDR, addr+1)
      val = (high << 8) + low
      return val
   
   def read_temperature():
      bus.write_byte_data(BMP180_ADDR, REG_CONTROL, REG_TEMP)
      time.sleep(0.005)  # Wait for conversion
      raw_temp = read_raw_data(REG_RESULT)
      temp = raw_temp / 340.0 + 36.53  # Example conversion formula
      return temp
   
   def read_pressure():
      bus.write_byte_data(BMP180_ADDR, REG_CONTROL, REG_PRESSURE)
      time.sleep(0.005)  # Wait for conversion
      raw_pressure = read_raw_data(REG_RESULT)
      pressure = raw_pressure / 256.0  # Example conversion formula
      return pressure
   
   if __name__ == "__main__":
      temp = read_temperature()
      pressure = read_pressure()
      print(f"Temperature: {temp:.2f} C")
      print(f"Pressure: {pressure:.2f} hPa")

4. Run the Script: Execute the Python script to read temperature and pressure data from the BMP180 sensor.

   python3 bmp180_read.py