3-2
MCF5282 User’s Manual
MOTOROLA
Introduction to the MAC
• A 48-bit accumulation data path to allow the use of a 40-bit product plus the addition
of 8 extension bits to increase the dynamic number range when implementing signal
processing algorithms.
The three areas of functionality are addressed in detail in following sections. The logic
required to support this functionality is contained in a MAC module, as shown in
Figure 3-1.
Figure 3-1. Multiply-Accumulate Functionality Diagram
3.2
Introduction to the MAC
The MAC is an extension of the basic multiplier found in most microprocessors. It is
typically implemented in hardware within an architecture and supports rapid execution of
signal processing algorithms in fewer cycles than comparable non-MAC architectures. For
example, small digital filters can tolerate some variance in an algorithm’s execution time,
but larger, more complicated algorithms such as orthogonal transforms may have more
demanding speed requirements beyond the scope of any processor architecture and may
require full DSP implementation.
To strike a balance between speed, size, and functionality, the ColdFire MAC is optimized
for a small set of operations that involve multiplication and cumulative additions.
Specifically, the multiplier array is optimized for single-cycle pipelined operations with a
possible accumulation after product generation. This functionality is common in many
signal processing applications. The ColdFire core architecture also has been modified to
allow an operand to be fetched in parallel with a multiply, increasing overall performance
for certain DSP operations.
Consider a typical filtering operation where the filter is defined as in Figure 3-2.
X
+/-
Operand Y
Operand X
Shift 0,1,-1
Accumulator(s)
Summary of Contents for ColdFire MCF5281
Page 124: ...3 20 MCF5282 User s Manual MOTOROLA EMAC Instruction Set Summary ...
Page 141: ...MOTOROLA Chapter 5 Static RAM SRAM 5 5 SRAM Programming Model ...
Page 142: ...5 6 MCF5282 User s Manual MOTOROLA SRAM Programming Model ...
Page 168: ...6 26 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 186: ...7 18 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 228: ...9 22 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 246: ...10 18 MCF5282 User s Manual MOTOROLA Low Power Wakeup Operation ...
Page 254: ...11 8 MCF5282 User s Manual MOTOROLA Memory Map and Registers ...
Page 264: ...12 10 MCF5282 User s Manual MOTOROLA Chip Select Registers ...
Page 280: ...13 16 MCF5282 User s Manual MOTOROLA Misaligned Operands ...
Page 314: ...14 34 MCF5282 User s Manual MOTOROLA MCF5282 External Signals ...
Page 339: ...MOTOROLA Chapter 15 Synchronous DRAM Controller Module 15 25 SDRAM Example ...
Page 340: ...15 26 MCF5282 User s Manual MOTOROLA SDRAM Example ...
Page 356: ...16 16 MCF5282 User s Manual MOTOROLA DMA Controller Module Functional Description ...
Page 408: ...17 52 MCF5282 User s Manual MOTOROLA Buffer Descriptors ...
Page 446: ...20 24 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 474: ...22 18 MCF5282 User s Manual MOTOROLA Programming Model ...
Page 510: ...23 36 MCF5282 User s Manual MOTOROLA Operation ...
Page 526: ...24 16 MCF5282 User s Manual MOTOROLA I2C Programming Examples ...
Page 672: ...28 12 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 718: ...29 46 MCF5282 User s Manual MOTOROLA Motorola Recommended BDM Pinout ...
Page 750: ...32 8 MCF5282 User s Manual MOTOROLA Ordering Information ...