Overview
MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
Freescale Semiconductor
1-5
The Version 2 ColdFire core has a 32-bit address bus and a 32-bit data bus. The address bus allows direct
addressing of up to 4 Gbytes. It supports misaligned data accesses and a bus arbitration unit for multiple
bus masters.
The Version 2 ColdFire supports an enhanced subset of the 68000 instruction set. The MAC provides new
instructions for DSP applications; otherwise, Version 2 ColdFire user code runs unchanged on 68020,
68030, 68040, and 68060 processors. The removed instructions include BCD, bit field, logical rotate,
decrement and branch, integer division, and integer multiply with a 64-bit result. Also, four indirect
addressing modes have been eliminated.
The ColdFire 2 core incorporates a complete debug module that provides real-time trace, background
debug mode, and real-time debug support.
1.2.2
System Integration Module (SIM)
The MCF5272 SIM provides the external bus interface for the ColdFire 2 architecture. It also eliminates
most or all of the glue logic that typically supports the microprocessor and its interface with the peripheral
and memory system. The SIM provides programmable circuits to perform address-decoding and chip
selects, wait-state insertion, interrupt handling, clock generation, discrete I/O, and power management
features.
1.2.2.1
External Bus Interface
The external bus interface (EBI) handles the transfer of information between the internal core and memory,
peripherals, or other processing elements in the external address space.
1.2.2.2
Chip Select and Wait State Generation
Programmable chip select outputs provide signals to enable external memory and peripheral circuits,
providing all handshaking and timing signals for automatic wait-state insertion and data bus sizing.
Base memory address and block size are programmable, with some restrictions. For example, the starting
address must be on a boundary that is a multiple of the block size. Each chip select is general purpose;
however, any one of the chip selects can be programmed to provide read and write enable signals suitable
for use with most popular static RAMs and peripherals. Data bus width (8-bit, 16-bit, or 32-bit) is
programmable on all chip selects, and further decoding is available for protection from user mode access
or read-only access.
1.2.2.3
System Configuration and Protection
The SIM provides configuration registers that allow general system functions to be controlled and
monitored. For example, all on-chip registers can be relocated as a block by programming a module base
address, power management modes can be selected, and the source of the most recent RESET or BERR
can be checked. The hardware watchdog features can be enabled or disabled, and the bus time-out period
can be programmed.
A software watchdog timer is also provided for system protection. If programmed, the timer causes a reset
to the MCF5272 if it is not refreshed periodically by software.
