LFEC datasheet(18/117 Pages) LATTICE

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2-15

Architecture

Lattice Semiconductor

LatticeECP/EC Family Data Sheet

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

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

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.

Width of Multiply

x18

x36

MULT

MAC

—

MULTADD

—

MULTADDSUM

—

Multiplier 0

Operand

Multiplier 1

Multiplier

(k-1)

Accumulator

Output

m/k

loops

Single

Multiplier

Operand

Accumulator

Operand

M loops

Function implemented in

General purpose DSP

Function implemented

in LatticeECP

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