Freescale Semiconductor MPC8260 - Manual (Page 1279)

MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 40-1
Chapter 40
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 PowerQUICC II applications. The reader may not obtain a full
understanding of the pin assignment capability described in this chapter without understanding the CPM
peripherals.
40.1 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
40.2 Port Registers
Each port has four memory-mapped, read/write, 32-bit control registers.
40.2.1 Port Open-Drain Registers (PODRA–PODRD)
The port open-drain register (PODR), shown in Figure 40-1 , indicates a normal or wired-OR configuration
of the port pins.