Programming Model
I/O Ports 10-15
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.
Figure 10-3. Interrupt Port Operation
Port D generates nine interrupt signals. Eight of these interrupts are genera ted by th e bi ts of ea ch 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 page9-12 for more details.
Pad
Data Register
Pull-up Enable Register
Pad
Buffer
Edge
Detect
Polarity Register
Interrupt Request Edge Register
Interrupt Request Enable Register
Bit IRQ
Keyboard Interrupt
0
SEL
1
Direction Register