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10.4.4
Port D Operation
Port D has the same functionality as other GPIO ports, except that it also has interrupt capabilities. It
should be used as either a general-purpose, interrupt-generating port or as a keyboard input port.
Figure 10-3 illustrates how this type of port operates.
Pull-up Enable Register
Polarity Register
Interrupt Request Edge Register
Data Register
Interrupt Request Enable Register
Direction Register
Port D generates nine interrupt signals. Eight of these interrupts are generated by the bits of each port. One
bit is the logical OR result of all eight bits, which is applied to the MC68VZ328 interrupt controller as a
level 4 keyboard interrupt (KB) in the interrupt status register. See Section 9.6.4, "Interrupt Status
Register," on page 9-12 for more details.
Pad
Buffer
Figure 10-3. Interrupt Port Operation
I/O Ports
Edge
Detect
0
SEL
1
• •
•
Pad
Programming Model
Bit IRQ
Keyboard Interrupt
10-15
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