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 |
Rev1 |
1/8 |
www.st.com
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 |
2/8
AN2855 |
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. |
Click recognition mode is enabled through specific commands sent to the device over the I2C bus that is available through dedicated pins (Figure 1).
Vdd |
|
|
|
|
|
Vdd_IO |
|
|
|
|
|
|
|
|
6 |
|
|
|
1 |
|
|
|
|
|
|
|
|
10uF |
|
Top VIEW |
|
|
|
|
|
|
|
|
|
||
100nF |
8 |
|
|
|
13 |
|
|
|
|
|
|
|
|
|
PC |
LC |
PD |
SIGN |
SDA |
SCL |
GND |
|
|
|
|
|
|
Digital signal from/to signal controller.Signal’s levels are defined by proper selection of Vdd_IO
AM03290v1
3/8