Using the Accelerometer on Windows Phone 7

There are two articles about this topic that is very helpful and I believe it will very helpful to you too. Go and take a loot at them since mine is an abbreviation of those: 31 Days of Windows Phone | Day #11: Accelerometer and Using the Accelerometer on Windows Phone 7 on The Windows Phone Developer Blog.

There are two major usages of the accelerometer:

1. Orientation relative to our planet Earth (assuming the device is being held steady)
2. Detecting movement of the device relative to the initial point (assuming you know the orientation).

The Accelerometer is in the Microsoft.Devices.Sensors namespace. We can get tree values: X, Y, Z from AccelerometerReadingEventArgs when ReadingChanged even fires.

The articles I've shown you said "Windows Phone devices that measures the acceleration on 3 axes (X, Y, Z), relative to freefall.  In addition to a timestamp, the values are expressed in G-forces (1G = 9.81 m/s²)."

• X is positive when the left edge of your phone is face up, on a perfectly flat surface; negative when the right edge of your phone is face up, on a perfectly flat surface. In addition, we assume that Y and Z would be 0 in this circumstance.
• Y is positive when the lower edge of your phone is face up, on a perfectly flat surface; negative when the upper edge of your phone is face up, on a perfectly flat surface.In addition, we assume that X and Z would be 0 in this circumstance.
• Z is positive when your phone is face down, on a perfectly flat surface; negative when your phone is face up, on a perfectly flat surface.In addition, we assume that X and Y would be 0 in this circumstance.

Note:

• Getting a value of 1.0 is not going to happen all the time. Earth’s gravity doesn’t roll that way.
• You will get those events often (Fifty times per second).
• There will be some calibration problems due to the nature of manufacturing tolerances (and users possibly dropping their phones a few times). Some devices will also come with edges that are not exactly flat. This means setting the device on a table may not result in a “level” reading. For applications using orientation, they need to really know that when the X and Y values are 0, the device is “leveled” (if “leveled” means the device is lying flat. If “leveled” means on edge then Z is 0, and either X or Y is 0).

For an example about how to detecting the movement of your device, go ahead take a look at "How do I get values from the WP7 Accelerometer?" in 31 Days of Windows Phone | Day #11: Accelerometer. The method ReadingChanged is obsoleted since Windows Phone 7.1 (Mango). You will get a warning when you compile you application. For a newer example on the new method CurrentValueChanged here: How to: Get Data from the Accelerometer Sensor for Windows Phone

For an example about how orientation, 31 Days of Windows Phone | Day #4: Device Orientation.