Overview
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor 8-1
Chapter 8 SDRAM Memory Controller

8.1 Overview

The following sections are contained in this document:
•Section 8.2, Terminology and Notation
•Section 8.3, Features
—Section 8.3.1, Devices Supported
•Section 8.4, Functional Description
—Section 8.4.1, External Signals (SDRAM Side)
—Section 8.4.2, Block Diagram
—Section 8.4.3, Transfer Size
—Section 8.4.4, Commands
•Section 8.5, Operation
—Section 8.5.1, Power-Up Initialization
•Section 8.6, Programming the SDRAM Controller
•Section 8.7, Memory Controller Registers (MBAR+0x0100:0x010C)

8.2 Terminology and Notation

Synchronous DRAM devices (SDR-SDRAM, DDR-SDRAM) are organized internally as columns by rows by “banks”. Older type
asynchronous DRAMs (FP, EDO) had rows and columns, but no internal banks. Historically, the word “bank” was often used to refer to the
set of memory devices all activated for the same address range (same RAS). To avoid confusion between these two meanings of “bank”, this
document uses the term “bank” for the internal banks of an SDRAM device, and the term “space” to indicate the memory device(s) activated
for a common address range (same CS).

8.2.1 “Endian”-ness

Endian-ness is a source of seemingly endless confusion, yet it need not be. The source of the confusion usually seems to be that bit number
and/or byte address are improperly equated with significance. In fact, bit number and byte address neither govern, nor imply, significance.
• Significance can only exist within an arithmetic context. An arithmetic context can be explicit or implicit.
•An explicit arithmetic context is the scope of an arithmetic operator, that is, the operand(s) and result(s).
•An implicit arithmetic context exists within any collection of bits representing an atomic arithmetic object, that is, a number.
Significance does not extend beyond the boundaries of the bit range.
• With a single exception, an arithmetic context, and therefore significance, can only exist within an execution context, that is, an
abstract process or the actual hardware to which it is mapped. The single exception is an implicit context: A byte is an implicit
arithmetic context.
• Within an atomic object “obj[m:n]”, in an arithmetic context, the most significant bit(byte) is on the left (m), and the least significant
bit(byte) is on the right (n), unless otherwise specified. The bit numbering and byte addressing order from left to right (ascending
or descending) is strictly cosmetic.
Note that “:” in “m:n” is an arithmetic operator, and therefore m and n are arithmetic objects within the operator scope. (If they
weren’t, then the terms “ascending” and “descending” would be meaningless.)
Note furthermore that the scope of the “:” operator does not include “obj”: obj could be of a non-arithmetic type. One particular
value (pattern of the bit range) of obj could represent “red”; another value might represent “cold”. The bit patterns are enumerations
of the legal values of obj; sometimes arithmetic operations on enumeration values are valid for the concepts they represent,
sometimes not.
An enumeration value is not an arithmetic context. An enumeration value is a representation of an object value; the nature of the
object itself need not be numeric.
The enumeration value of a collection of bits (e.g. process variable) is only meaningful in the context of a process which manipulates those
bits in a manner consistent with the concept they represent. (A process itself may be just a concept represented by a collection of bits
manipulated (by a processing unit) in a manner consistent with the concept they represent.) And in the context of the concept they represent,
bits and bytes may have significance.
But while transporting bits from one location to another, the hardware transport media almost never have any knowledge of the concepts
represented by the data, or the contexts in which they are valid (this does not include protocol bits of the media, which may be added and