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Freescale Semiconductor
7-1
Chapter 7
Static RAM (SRAM)
7.1
Introduction
This chapter describes the on-chip static RAM (SRAM) implementation, including general operations,
configuration, and initialization. It also provides information and examples showing how to minimize
power consumption when using the SRAM.
7.1.1
Overview
The SRAM module provides a general-purpose memory block that the ColdFire processor can access in a
single cycle. The location of the memory block can be specified to any 0-modulo-32K address within the
256-Mbyte address space (0x8000_0000 – 0x8FFF_FFFF). The memory is ideal for storing critical code
or data structures or for use as the system stack. Because the SRAM module is physically connected to the
processor's high-speed local bus, it can service processor-initiated accesses or memory-referencing
commands from the debug module.
Depending on configuration information, processor references may be sent to the cache and the SRAM
block simultaneously. If the reference maps into the region defined by the SRAM, the SRAM provides the
data back to the processor, and the cache data is discarded. Accesses from the SRAM module are not
cached.
The SRAM is dual-ported to provide access for any of the bus masters via the SRAM backdoor on the
crossbar switch. The SRAM is partitioned into two physical memory arrays to allow simultaneous access
to arrays by the processor core and another bus master. For more information on arbitration between
multiple masters accessing the SRAM, see
Chapter 15, “Crossbar Switch (XBS)
”
7.1.2
Features
The major features includes:
•
One 32 Kbyte SRAM
•
Single-cycle access
•
Physically located on the processor's high-speed local bus
•
Memory location programmable on any 0-modulo-32 Kbyte address
•
Byte, word, and longword address capabilities
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...