Achronix Speedster22i User Macro Guide Bedienungsanleitung PDF herunterladen (Seite 93)

Registers DFFNS

Speedster22i Macro Cell Library

AchronixSemiconductorProprietary PAGE 77

DFFNS

Negative Clock Edge D-Type Register with Asynchronous Set

ckn

DFFNS

Figure 2-13: Logic Symbol

DFFNS is a si

ngle D‐type register with data input (d), clock (ckn), and active‐low set (sn)

inputs and data (q) output. The active‐low set input overrides all other inputs when it is

assertedlowandsetsthedataoutputhigh.Iftheasynchronoussetinputisnotasserted,the 

dataoutputissettotheva

lueonthedatainputuponthe nextfallingedgeoftheclock.

Pins

Table 2-42: Pin Descriptions

Name Type Description

d Data input.

Active-low asynchronous set input. A lo

w on sn sets the q output high

independent of the other inputs.

ckn Negative-edge clock input.

Data output. The value pr

esent on the data input is transferred to the q

output upon the falling edge of the clock if the asynchronous set input is

high.

Parameters

Table 2-43: Parameters

Parameter Defined Values Default Value

init 1’b1

sr_assertion “unclocked”

init

The init parameter defines the initial value of the output of the DFFNS register.This isthe

valuetheregistertakesupontheinitialapplicationofpowertotheFPGA.Thedefaultvalue

oftheinitparameteris1’b1.

sr_assertion

The sr_assertion param eter defines the behavior of the output when the sn set input is

asserted.Assigningthesr_assertionto“unclocked”resultsinanasychronousassertionofthe

reset signal, where the q output is set to one upon assertion of the active‐low reset signal.

Assigningthesr_assertionto“clocked”re

sultsinasynchronousassertionoftheresetsignal,

wheretheqoutputissettooneatthenextrisingedgeoftheclock.Thedefaultvalueofthe

sr_assertionparameteris“unclocked”.

input

output

1’b0, 1’b1

“unclocked”, “clocked”

1 2 ... 88 89 90 91 92 93 94 95 96 97 98 ... 223 224

Kommentare zu diesen Handbüchern

Keine Kommentare

Achronix Speedster22i User Macro Guide Bedienungsanleitung Seite 93

Kommentare zu diesen Handbüchern