used, this line requires an external 1.8 kpull-up.
Serial Interface 1 (SI1): I
2
C™_SCL0/SPI_MOSI. When I
2
C™ is
used, this line requires an external 1.8 kpull-up.
Serial Interface 2 (SI2): I
2
C™_SDA1/SPI_CS. When I
2
C™ is
used, this line requires an external 1.8 kpull-up.
Serial Interface 3 (SI3): I
2
C™_SCL1/SPI_SCLK. When I
2
C™ is
used, this line requires an external 1.8 kpull-up.
Master Clear (Reset) input. This pin is an active-low Reset to the
device. It requires external 10 kpull-up.
Transmit electrode connection.
Reserved: do not connect.
Common ground reference for analog and digital domains.
Positive supply for peripheral logic and I/O pins.
It requires an external filtering capacitor (100 nF).
Exposed pad. It should be connected to Ground.
ST
ST
ST
ST
—
—
—
I/O
I/O
I/O
I/O
I/O
I/P
O
—
ST
ST
ST
ST
ST
ST
Analog
—
—
—
—
P
P
P
Legend:
P = Power; ST = Schmitt Trigger input with CMOS levels; O = Output; I = Input;
— = N/A
2012 Microchip Technology Inc.
Advance Information
DS41667A-page 3
MGC3130
Table of Contents
1.0
Theory of Operation: Electrical Near-Field (E-Field Sensing).................................................................................................... 5
System Architecture.................................................................................................................................................................. 9
Development Support .............................................................................................................................................................. 29
10.0 Packaging Information ............................................................................................................................................................. 31
Index .................................................................................................................................................................................................... 35
The Microchip Web Site ....................................................................................................................................................................... 36
Customer Change Notification Service ................................................................................................................................................ 36
Customer Support ................................................................................................................................................................................ 36
Product Identification System .............................................................................................................................................................. 38
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DS41667A-page 4
Advance Information
2012 Microchip Technology Inc.
MGC3130
1.0
THEORY OF OPERATION:
ELECTRICAL NEAR-FIELD
(E-FIELD) SENSING
FIGURE 1-1:
EQUIPOTENTIAL LINES
OF AN UNDISTORTED
E-FIELD
Microchip’s GestIC is a 3D sensor technology which
utilizes an electric field (E-field) for advanced proximity
sensing. It allows realization of new user interface
applications by detection, tracking and classification of
a user’s hand or finger motion in free space.
E-fields are generated by electrical charges and
propagate three-dimensionally around the surface,
carrying the electrical charge.
Applying direct voltages (DC) to an electrode results in
a constant electric field. Applying alternating voltages
(AC) makes the charges vary over time and thus, the
field. When the charge varies sinusoidal with frequency
f, the resulting electromagnetic wave is characterized
by wavelength
λ
= c/f, where c is the wave propagation
velocity — in vacuum the speed of light. In cases where
the wavelength is much larger than the electrode
geometry, the magnetic component is practically zero
and no wave propagation takes place. The result is
quasi-static electrical near field that can be used for
sensing conductive objects such as the human body.
Microchip’s GestIC technology uses transmit (Tx)
frequencies in the range of 100 kHz which reflects a
wavelength of about three kilometers. With electrode
geometries of typically less than twenty by twenty
centimeters, this wavelength is much larger in
comparison.
In case a person’s hand or finger intrudes the electrical
field, the field becomes distorted. The field lines are
drawn to the hand due to the conductivity of the human
body itself and shunted to ground. The three-
dimensional electric field decreases locally. Microchip’s
GestIC technology uses a minimum number of four
receiver (Rx) electrodes to detect the E-field variations
at different positions to measure the origin of the
electric field distortion from the varying signals
received. The information is used to calculate the
position, track movements and to classify movement
patterns (gestures).
The simulation results in
Figure 1-1
and
Figure 1-2
show the influence of an earth-grounded body to the
electric field. The proximity of the body causes a com-
pression of the equipotential lines and shifts the Rx
electrode signal levels to a lower potential which can be
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