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→Accelerometer
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== Accelerometer ==
== Accelerometer ==
[[File:Wii-Remote-Accel.jpg|right|thumb|200px|ADXL330 in a Wii remote]][[File:Wiimote_axis2.png|right|thumb|200px|Coordinate system used by Wii Remote]]
[[File:Wii-Remote-Accel.jpg|right|thumb|200px|ADXL330 in a Wii remote]][[File:Wiimote_axis2.png|right|thumb|200px|Coordinate system used by Wii Remote]]
−The Wii Remote includes a three-axis linear accelerometer located on the top suface of the circuit board, slightly left of the large A button. The integrated circuit is the [http://www.analog.com/en/prod/0%2C2877%2CADXL330%2C00.html ADXL330] ([http://www.analog.com/UploadedFiles/Data_Sheets/ADXL330.pdf data sheet]), manufactured by Analog Devices. This device is physically rated to measure accelerations over a range of at least +/- 3g with 10% sensitivity.
+The Wii Remote includes a three-axis linear accelerometer located on the top suface of the circuit board, slightly left of the large A button. The integrated circuit is the [http://www.seekic.com/icdata/%20ADXL330.html ADXL330] ([http://www.analog.com/UploadedFiles/Data_Sheets/ADXL330.pdf data sheet]), manufactured by Analog Devices. This device is physically rated to measure accelerations over a range of at least +/- 3g with 10% sensitivity.
Since the accelerometer actually measures the force exerted by a set of small proof masses inside of it with respect to its enclosure, the accelerometer measures linear acceleration in a free fall frame of reference. If the Wii Remote is in free fall, it will report zero acceleration. At rest, it will report an upward acceleration (+Z, when horizontal) equal to the acceleration due to gravity, g (approximately 9.8 m/s²) but in the opposite direction. This fact can be used to derive tilt from the acceleration outputs when the Wii Remote is reasonably still.
Since the accelerometer actually measures the force exerted by a set of small proof masses inside of it with respect to its enclosure, the accelerometer measures linear acceleration in a free fall frame of reference. If the Wii Remote is in free fall, it will report zero acceleration. At rest, it will report an upward acceleration (+Z, when horizontal) equal to the acceleration due to gravity, g (approximately 9.8 m/s²) but in the opposite direction. This fact can be used to derive tilt from the acceleration outputs when the Wii Remote is reasonably still.