ECP2 datasheet(24/386 Pages) LATTICE

24 / 386 page

2-21

Architecture

Lattice Semiconductor

LatticeECP2/M Family Data Sheet

If an EBR is pre-loaded during conﬁguration, the GSR input must be disabled or the release of the GSR during

device Wake Up must occur before the release of the device I/Os becomes active.

These instructions apply to all EBR RAM and ROM implementations.

Note that there are no reset restrictions if the EBR synchronous reset is used and the EBR GSR input is disabled.

sysDSP™ Block

The LatticeECP2/M family provides a sysDSP block, making it ideally suited for low cost, high performance Digital

Signal Processing (DSP) applications. Typical functions used in these applications are Finite Impulse Response

(FIR) ﬁlters, Fast Fourier Transforms (FFT) functions, Correlators, Reed-Solomon/Turbo/Convolution encoders and

decoders. These complex signal processing functions use similar building blocks such as multiply-adders and mul-

tiply-accumulators.

sysDSP Block Approach Compared to General DSP

Conventional general-purpose DSP chips typically contain one to four (Multiply and Accumulate) MAC units with

ﬁxed data-width multipliers; this leads to limited parallelism and limited throughput. Their throughput is increased by

higher clock speeds. The LatticeECP2/M, on the other hand, has many DSP blocks that support different data-

widths. This allows the designer to use highly parallel implementations of DSP functions. The designer can opti-

mize the DSP performance vs. area by choosing an appropriate level of parallelism. Figure 2-22 compares the fully

serial and the mixed parallel and serial implementations.

Figure 2-22. Comparison of General DSP and LatticeECP2/M Approaches

sysDSP Block Capabilities

The sysDSP block in the LatticeECP2/M 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 LatticeECP2/M 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. In the LatticeECP2/

M family the DSP elements can be concatenated.

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

Multiplier 0

Operand

Multiplier 1

Multiplier k

(k adds)

Output

m/k

loops

Single

Multiplier

Operand

Accumulator

Operand

M loops

Function implemented in

General purpose DSP

Function implemented

in LatticeECP2/M

m/k

accumulate

ECP2 Datasheet(PDF) 24 Page - Lattice Semiconductor

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