The BMP280 is a small sensor that measures Barometric Pressure (the weight of the air), temperature, and as a result elevation as well. I became interested in this sensor to measure the elevation of a model rocket at it's peak, but can also be used for weather sensing, or even predicting optimal fish biting times!
The BMP280 is fairly easy to setup and use, is very cheap, and impressively accurate (±1 hPa).
Step 1: Parts
Step 2: Wiring
In this example connect the following BMP280 pins to the Arduino respectively, VCC to 3.3V, GND to GND, SCL to A5, and SDA to A4.
Step 3: Libraries
Before we get to the actual code you will need to install the following libraries:
Once the libraries are downloaded, place them in the Arduino>Libraries folder. Go to the Adafruit_BMP_280 library folder and open Adafruit_BMP280.h using notepad. Find the I2C address and change it to 0x76 (see photo). Save and close.
Step 4: Sketch
Download and upload the attached sketch. Use the serial monitor to see what your new sensor is picking up. To use this in future projects, consider utilizing a Data Logging Shield to record your findings remotely.