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Pen Interrupts
9.7
Keyboard Interrupts
Keyboard interrupt features provide a smart power-management capability. The CPU core can be put to
sleep when no key is being pressed. Once a key is pressed, however, the core wakes up to service the
request. This event-driven approach significantly reduces power consumption. KB0 to KB7 (multiplexed
with INT[3:0], IRQ1, IRQ2, IRQ3, and IRQ6) are input pins for the keyboard interface. They are internally
ORed together and generate an interrupt that indicates to the core that a key has been pressed.
9.8
Pen Interrupts
The MC68VZ328 is designed to support pen and touch panel inputs. In most of these systems, the setup
involves a touch panel connected to an analog-to-digital (A/D) converter and the microprocessor. To
achieve low power consumption and system performance, the A/D is usually connected to an interrupt of
the microprocessor. When the touch panel is touched, the CPU is activated through the interrupt and the
A/D starts collecting data. On the MC68VZ328, IRQ5 is a level 5 interrupt with pull-up properties that is
normally used as a pen interrupt. Connecting the IRQ5 to a transistor network with the A/D, a pen-down
interrupt can be implemented with the MC68VZ328 system. With the special design circuitry inside, this
pen interrupt supports both pen-down and pen-up interrupts. The polarity of the pen interrupt can be set by
programming the POL5 bit of the interrupt control register.
9-20
MC68VZ328 User's Manual
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