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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Theory of operation AN2855
1.2 Entering single click recognition mode
To enable the single-click recognition function, the device must first be configured for powerdown mode driving PD pin to GND. Then the following sequence of commands must be sent
to the device through I
I2C_Read(0x5D, 0x16, Value_1);
I2C_Write(0x5D, 0x16, Value_1 & 0x1F);
I2C_Write(0x1D, 0x3Bh, 0x77h);
I2C_Write(0x1D, 0x3Ch, 0x07h);
I2C_Write(0x1D, 0x3Dh, 0xFEh);
I2C_Write(0x1D, 0x3Eh, 0x10h);
I2C_Write(0x1D, 0x3Fh, 0xFFh);
I2C_Write(0x1D, 0x38h, 0x15h);
I2C_Write(0x1D, 0x20h, 0x47h);
I2C_Write(0x1D, 0x22h, 0x07h);
where I2C_Read and I2C_Write have the following syntax:
2
C bus:
I2C_Read(SlaveAddress, SubAddress, DestinationValue);
I2C_Write(SlaveAddress, SubAddress, SourceValue);
At the end of the sequence the device will be in a power on state, ready to operate in singleclick recognition mode and orientation detection is no longer active.
1.3 Entering double-click recognition mode
As with single-click recognition, to enable the double-click recognition function the device
must be first configured for power-down mode driving PD pin to GND. Then the following
sequence of commands must be sent to the device through I
I2C_Read(0x5D, 0x16, Value_1);
I2C_Write(0x5D, 0x16, Value_1 & 0x1F);
I2C_Write(0x1D, 0x3Bh, 0x77h);
I2C_Write(0x1D, 0x3Ch, 0x07h);
I2C_Write(0x1D, 0x3Dh, 0xFEh);
I2C_Write(0x1D, 0x3Eh, 0x10h);
I2C_Write(0x1D, 0x3Fh, 0xFFh);
2
C bus:
I2C_Write(0x1D, 0x38h, 0x2Ah);
I2C_Write(0x1D, 0x20h, 0x47h);
I2C_Write(0x1D, 0x22h, 0x07h);
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AN2855 Theory of operation
At the end of the sequence, the device will be in a power on state, ready to operate in
double-click recognition mode and orientation detection is no longer active.
1.4 Exiting click recognition mode
To exit from the click recognition function and restore the orientation detection, the device
must be first be turned off by switching off the power supply, then turned on.
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Power-down mode AN2855
2 Power-down mode
When the FC30 is operating in click or double-click recognition mode, the PD pin must be
tied to GND and no longer enabling the power-down mode. Power-down mode is still
available through dedicated I
2.1 Entering power-down mode
To enter the power-down mode, send the following I2C command to the device:
I2C_Write(0x1D, 0x20h, 0x00h);
2.2 Exiting power-down mode
To exit the power-down mode, send the following I2C command to the device:
I2C_Write(0x1D, 0x20h, 0x47h);
2
C commands.
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AN2855 Revision history
3 Revision history
Table 1. Document revision history
Date Revision Changes
17-Feb-2009 1 Initial release.
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AN2855
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