ST AN2855 Application note
AN2855
Application note
Configuration for single-click
and double-click detection using the FC30
Introduction
This document is intended to provide application information for the click and double-click
detection functions of the FC30.
When a single or double mechanical tap is detected, the FC30 provides an interrupt signal,
enabling a “mouse button-like” function for intuitive man-machine interface solutions.
A power-down mode selectable through a dedicated command ensures very low current
consumption in battery-operated devices.
February 2009 Rev 1 1/8
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Contents AN2855
Contents
1 Theory of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Device pinout for click recognition mode . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Entering single click recognition mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Entering double-click recognition mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Exiting click recognition mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Power-down mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Entering power-down mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Exiting power-down mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
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AN2855 Theory of operation
1 Theory of operation
The click recognition function featured in the FC30 helps to create a man-machine interface
with little software loading. The device can be configured to output an interrupt signal on a
dedicated pin when tapped in any direction.
If the sensor is exposed to a single input stimulus, it generates an interrupt request on
inertial interrupt pin PC. A more advanced feature allows the generation of an interrupt
request when a double input stimulus with fixed time between the two events is recognized,
enabling a mouse button-like functionality.
Note: While the device is operating in click/double-click recognition mode, the orientation
detection function is not available.
1.1 Device pinout for click recognition mode
Click recognition mode is enabled through specific commands sent to the device over the
2
I
C bus that is available through dedicated pins (Figure 1).
Figure 1. FC30 pinout - I
Vdd
10uF
100nF
GND
Digital signal from/to signal controller.Signal’s levelsare defined byproperselection of Vdd_IO
2
C pins for click recognition mode
6
Top VIEW
8
PC
LC
PD
Vdd_IO
1
13
SDA
SIGN
SCL
AM03290v1
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