MOTOROLA
Chapter 6. System Configuration and Protection
6-1
Chapter 6
System Configuration and Protection
The MPC565/MPC566 incorporates many system functions that normally must be
provided in external circuits. In addition, it is designed to provide maximum system
safeguards again hardware and/or software faults. The system configuration and protection
sub-module provides the following features:
System Configuration—The USIU allows the configuration of the system according
to the particular requirements. The functions include control of show cycle
operation, pin multiplexing, and internal memory map location. System
configuration also includes a register containing part and mask number constants to
identify the part in software.
Interrupt Controller—The interrupt controller receives interrupt requests from a
number of internal and external sources and directs them on a single
interrupt-request line to the RCPU.
General-Purpose I/O—The USIU provides 64 pins for general-purpose I/O. The
SGPIO pins are multiplexed with the address and data pins.
External Master Modes Support—External master modes are special modes of
operation that allow an alternate master on the external bus to access the internal
modules for debugging and backup purposes.
Bus Monitor—The SIU provides a bus monitor to watch internal to external
accesses. It monitors the transfer acknowledge (TA) response time for internal to
external transfers. A transfer error acknowledge (TEA) is asserted if the TA response
limit is exceeded. This function can be disabled.
Software Watchdog Timer (SWT)—The SWT asserts a reset or non-maskable
interrupt, as selected by the system protection control register (SYPCR), if the
software fails to service the SWT for a designated period of time (e.g., because the
software is trapped in a loop or lost). After a system reset, this function is enabled
with a maximum time-out period and asserts a system reset if the time-out is
reached. The SWT can be disabled or its time-out period can be changed in the
SYPCR. Once the SYPCR is written, it cannot be written again until a system reset.
Periodic Interrupt Timer (PIT)—The SIU provides a timer to generate periodic
interrupts for use with a real-time operating system or the application software. The