Weatherstation - Barometric Pressure Sensor

I ended up getting a BMP180 pressure sensor. I also made a major change to my weatherstation: I have decided to make the transmitter using a 430G2553 microprocessor. By using deep sleep mode and only taking readings every 30 s or so, I can run the weatherstation off of two D batteries for much longer than an Arduino.

Components

1. TI launchpad w/MSP430G2553
2. BMP180 breakout board

Connections

VCC --> Launchpad VCC
GND --> Launchpad GND
SCL --> P1.6
SDA --> P1.7

Remove the P1.6 LED jumper as well.

How It Works

I modified the code to give pressure readings in inHg and temperature in Fahrenheit. To get temperature readings in Celsius, instantiate the BMP085 library with the argument BMP085_C. Pressure is returned by default in hPa.

Interestingly, there are high precision modes, which can be activated when the BMP085 library is instantiated. I'm not using these, because I want to keep code size and power consumption low.

Before I setup my final weatherstation design, I'm considering going through the BMP085 library code and removing the temperature sensor functions, since I already have a dedicated temperature sensor. If not, I could just average both temperature sensor readings, so I'm not wasting  clock cycles on unused data.

Show Code

I used the BMP085 Template Library, which works fine with a BMP180. Here is some sample code that I've modified:

// Author: Zac DeMeo
// Uses BMP085 sensor library https://github.com/astuder/BMP085-template-library-Energia

// Import BMP085 sensor libraries
#include <Wire.h>          
#include <BMP085_t.h>       

BMP085<0, 0, BMP085_F> PSensor;         // Instantiate sensor, 0 = low precision pressure reading

void setup() {
  Serial.begin(9600);      // Debugging only
  Wire.begin();            // Initialize I2C for pressure sensor
  PSensor.begin();         // Initialize pressure sensor
}

void loop() {
  PSensor.refresh();                    // read current sensor data
  PSensor.calculate();                  // run calculations for temperature and pressure

  float p = (PSensor.pressure+50)*0.0002953;   // Get pressure in inHg
  float t = (PSensor.temperature/10.0); // Get temperature in F

  Serial.print("Pressure: ");
  Serial.print(p);
  Serial.print(" inHg");
  Serial.println();
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.print(" F");
  Serial.println();

  delay(2000);
}