I recently purchased a 10 Degrees of Freedom (10DOF) sensor from eBay called a GY-80. It’s a compact module that includes a gyroscope, accelerometer, digital compass, and a barometric pressure / temperature sensor.
All of the individual sensors are accessible over I2C so you only need 4 connections to access all those sensors. SDA, SCL, Ground and VCC (you can use 3.3v or 5v).
Each component can be accessed individually. I was planning on doing a write-up on each one, but it looks like Bildr beat me to the punch as they already have a great tutorial for each component. Here are the links to the datasheets and tutorials for each component:
This module can be used individually as the articles above show but they can also be monitored at the same time. MultiWii is an open source software project that is used as the brain of multi-copter projects. The code runs on Arduino and it is compatible with a large variety of sensors (the GY80 being one of them). It does require a little tinkering to get it working properly. I’ll document the process in a future article. Also since this module works over I2C it can also be accessed using a Raspberry Pi.