3-2
MCF5272 User’s Manual
Overview
Figure 3-1. ColdFire MAC Multiplication and Accumulation
The MAC unit is an extension of the basic multiplier found on most microprocessors. It can
perform operations native to signal processing algorithms in an acceptable number of
cycles, given the application constraints. For example, small digital filters can tolerate some
variance in the execution time of the algorithm; larger, more complicated algorithms such
as orthogonal transforms may have more demanding speed requirements exceeding the
scope of any processor architecture and requiring a fully developed DSP implementation.
The M68000 architecture was not designed for high-speed signal processing, and a large
DSP engine would be excessive in an embedded environment. In striking a middle ground
between speed, size, and functionality, the ColdFire MAC unit is optimized for a small set
of operations that involve multiplication and cumulative additions. Specifically, the
multiplier array is optimized for single-cycle, 16 x 16 multiplies producing a 32-bit result,
with a possible accumulation cycle following. This is common in a large portion of signal
processing applications. In addition, the ColdFire core architecture has been modified to
allow for an operand fetch in parallel with a multiply, increasing overall performance for
certain DSP operations.
3.1.1 MAC Programming Model
Figure 3-2 shows the registers in the MAC portion of the user programming model.
Figure 3-2. MAC Programming Model
31
0
MACSR
MAC status register
ACC
MAC accumulator
MASK
MAC mask register
X
+/-
Operand Y
Operand X
Shift 0,1,-1
Accumulator
Summary of Contents for DigitalDNA ColdFire MCF5272
Page 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Page 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Page 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Page 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Page 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Page 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Page 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Page 338: ...13 44 MCF5272 User s Manual Application Examples ...
Page 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Page 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Page 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Page 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...