MPC555 / MPC556
MEMORY CONTROLLER
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
10-1
SECTION 10
MEMORY CONTROLLER
The memory controller generates interface signals to support a glueless interface to
external memory and peripheral devices. It supports four regions, each with its own
programmed attributes. The four regions are reflected on four chip-select pins. Read
and write strobes are also provided.
The memory controller operates in parallel with the external bus interface to support
external cycles. When an access to one of the memory regions is initiated, the memory
controller takes ownership of the external signals and controls the access until its ter-
mination. Refer to
.
Figure 10-1 Memory Controller Function Within the USIU
10.1 Overview
The memory controller provides a glueless interface to EPROM, static RAM (SRAM),
Flash EPROM (FEPROM), and other peripherals. The general-purpose chip-selects
are available on lines CS[0] through CS[3]. CS[0] also functions as the global (boot)
Internal Bus
EBI Bus
Memory Controller
U-bus
Interface
External
Bus
Interface
Memory
Controller
ADDR[0:31]
DATA[0:31]
Control Bus
WE[0:3]/BE[0:3]
OE
CS[0:3]
Bus
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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