Altera DQ (ALTDQ) Instrukcja Użytkownika Pobierz pdf (Strona 2)

Page 2 Introduction

DQ (ALTDQ) and DQS (ALTDQS) Megafunctions November 2010 Altera Corporation

■ Stratix

■ Stratix GX

■ Stratix II

■ Stratix II GX

ALTDQ Megafunction

The ALTDQ megafunction allows you to easily configure the DDR I/O elements in

supported Altera devices for DQ data signal functionality. The ALTDQ megafunction

is a variation of the ALTDDIO_BIDIR megafunction modified to be used with the

ALTDQS megafunction.

The ALTDQ megafunction implements a DDR interface and offers many additional

features, which include:

■ Transmission and reception of data on both edges of the reference clock

■

ddioinclk

clock input for the negative-edge input register (available for Stratix II

devices only)

■ Active high asynchronous clear and clock-enable control inputs

■ Registered or unregistered output-enable input

ALTDQS Megafunction

The ALTDQS megafunction allows you to easily configure the I/O elements of the

data strobe (DQS) in supported Altera devices.

You typically use the ALTDQS megafunction used with the ALTDQ megafunction

which provides the following features:

■ A group of DQS pins used to strobe the read and write data in external DDR

memory interfaces using a common DLL to phase shift the read strobe

■ Implementing one DLL and a number of user-specified DQS pins (the maximum

number of DQS supported by a DLL is also dependent on the device side)

■ Clocks generated for the DQ negative-edge input registers from the DQSn pins

that is the

dqddioinclk[]

signal (available for Stratix II devices only)

■ Delay buffer setting output option

■ Frequency settings of DQS inputs and system reference clock

■ Active-high asynchronous clear and clock-enable control inputs

■ Registered or unregistered output-enable input

■ DQS outputs configurable as open drain mode

■ Speed setting of the DQS and delay buffers as either low or high (available for

Stratix II devices only)

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Altera DQ (ALTDQ) Instrukcja Użytkownika Strona 2