LFECP20E-5F900C 查看數據表（PDF） - Lattice Semiconductor

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LFECP20E-5F900C

LatticeECP/EC Family Data Sheet Introduction

Lattice Semiconductor 

Lattice Semiconductor

Architecture

LatticeECP/EC Family Data Sheet

Figure 2-17. Comparison of General DSP and LatticeECP-DSP Approaches

Operand

A

Operand

B

Single

Multiplier

x

Operand

A

Operand

A

Operand

B

Operand

B

M loops

x x Multiplier 0

Multiplier 1

Operand

A

Operand

B

x

Multiplier

(k-1)

m/k

loops

Σ Accumulator

Function implemented in

General purpose DSP

Σ Accumulator

Output

Function implemented

in LatticeECP

sysDSP Block Capabilities

The sysDSP block in the LatticeECP-DSP family supports four functional elements in three 9, 18 and 36 data path

widths. The user selects a function element for a DSP block and then selects the width and type (signed/unsigned)

of its operands. The operands in the LatticeECP-DSP family sysDSP Blocks can be either signed or unsigned but

not mixed within a function element. Similarly, the operand widths cannot be mixed within a block.

The resources in each sysDSP block can be configured to support the following four elements:

• MULT

(Multiply)

• MAC

(Multiply, Accumulate)

• MULTADD

(Multiply, Addition/Subtraction)

• MULTADDSUM (Multiply, Addition/Subtraction, Accumulate)

The number of elements available in each block depends in the width selected from the three available options x9,

x18, and x36. A number of these elements are concatenated for highly parallel implementations of DSP functions.

Table 2-1 shows the capabilities of the block.

Table 2-7. Maximum Number of Elements in a Block

Width of Multiply

x9

MULT

8

MAC

4

MULTADD

4

MULTADDSUM

2

x18

x36

4

1

2

—

2

—

1

—

Some options are available in four elements. The input register in all the elements can be directly loaded or can be

loaded as shift register from previous operand registers. In addition by selecting ‘dynamic operation’ in the ‘Signed/

Unsigned’ options the operands can be switched between signed and unsigned on every cycle. Similarly by select-

ing ‘Dynamic operation’ in the ‘Add/Sub’ option the Accumulator can be switched between addition and subtraction

on every cycle.

2-15

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