This sample uses the Monkey.Robotics component in a Xamarin.Forms app to connect using Bluetooth LE to the TI SensorTag and access data from various sensors including temperature, accelerometer, pressure, humidity, and gyroscope (NOTE: code for parsing the barometer data is currently incomplete).

Here's a device shown next to the app running on an iPhone 6:

The complete screenflow for the iOS app (showing the Magnometer sensor) is below. The app works like a 'browser', first locating Bluetooth LE devices to connect to, then connecting and discovering services and their characteristics, finally allowing you to set and query specific characteristics. This app example has hardcoded references to the characteristics exposed by the TI SensorTag.

Here is the complete screenflow for the Android app (showing the Magnometer sensor):

The Xamarin.Forms common code has a direct assembly reference to Robotics.Mobile.Core.dll in the Components directory, because components cannot be added to PCL projects.

The Monkey.Robotics component (and this app!) is in 'beta' and is provided to learn about using Bluetooth LE with Xamarin.Forms.

You can buy the TI SensorTag on Amazon, and they also have their own app for iOS, Android, and Windows (to play with and compare data outputs).

The component that contains the Bluetooth LE abstraction for Xamarin.Forms is open-source, and is available on github. As noted on the component page it is still in beta.