Motorola PowerQUICC II MPC8280 Series Reference Manual page 1395

Chapter 41
Parallel I/O Ports
The CPM supports four general-purpose I/O ports—ports A, B, C, and D. Each pin in the
I/O ports can be configured as a general-purpose I/O signal or as a dedicated peripheral
interface signal. Port C is unique in that 16 of its pins can generate interrupts to the interrupt
controller.
Each pin can be configured as an input or output and has a latch for data output, read or
written at any time, and configured as general-purpose I/O or a dedicated peripheral pin.
Part of the pins can be configured as open-drain (the pin can be configured in a wired-OR
configuration on the board). The pin drives a zero voltage but three-states when driving a
high voltage.
Note that port pins do not have internal pull-up resistors. Due to the CPM's significant
flexibility, many dedicated peripheral functions are multiplexed onto the ports. The
functions are grouped to maximize the pins' usefulness in the greatest number of MPC8280
applications. The reader may not obtain a full understanding of the pin assignment
capability described in this chapter without understanding the CPM peripherals.
41.1 Features
The following is a list of the parallel I/O ports' important features:
• Port A is 32 bits
• Port B is 28 bits
• Port C is 32 bits
• Port D is 28 bits
• All ports are bidirectional
• All ports have alternate on-chip peripheral functions
• All ports are three-stated at system reset
• All pin values can be read while the pin is connected to an on-chip peripheral
• Open-drain capability on some pins
• Port C offers 16 interrupt input pins
MOTOROLA
Freescale Semiconductor, Inc.
Chapter 41. Parallel I/O Ports
For More Information On This Product,
Go to: www.freescale.com
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