Rainbow Electronics AT42QT5480 - Manual (Page 7)

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9510AS–AT42–10/08
QT5480
2. Overview of the QT5480
2.1 Introduction
The QT5480 is a versatile capacitive touchscreen controller, able to support a diagonal
touchscreen of up to 8 inches. The IC supports Two Touch
™ operation, part of the QTwo ™ family
of devices from Atmel ® .
The QT5480 uses Atmel's patented QMatrix ™ capacitive sensing technique, which offers
excellent moisture tolerance, fast acquisition and outstanding ground load immunity.
A unique feature of the QT5480 is that it allows a choice to be made as to how many of the
capacitive measurement channels form part of a touchscreen, and which ones form discrete
keys or sliders.
This controller offers unrivalled flexibility to create touchscreens, sliders and keys. The device can
report two touches on a touchscreen making it suitable for next generation touch interfaces.
Concurrent use of a touchscreen plus keys or sliders is also possible.
By treating all capacitive channels equally during measurement, and then applying additional signal
processing, the device allows the channels to be used as part of a touchscreen, or part of one or more
sliders, or as discrete touch keys.
Touchscreens can be created that are of arbitrary channel length and width. Channels not used in the
touchscreen can either be turned into sliders or keys. There are some constraints on the starting
channels for touchscreens and sliders, but these have no practical impact for most applications.
The controller also has the ability to save a Y line when configuring a touchscreen, reusing it in the
touchscreen pattern at the two edges. This saved Y line can then be used to create extra objects like
a slider or multiple keys, while allowing the touchscreen to be sized as though it was “one Y line
larger”. In this “wrapped Y line” mode Two Touch processing cannot be used.
See Figure 2-1 for configuration examples.