Altera ALTDLL Manual de usuario descargar pdf (Pagina 38)

Chapter 4: Functional Description 4–2

Custom External Memory Interface Datapaths Overview

f For more information about the blocks available in the datapaths for your target

device family, refer to the following chapters in the device handbook:

■ External Memory Interfaces in HardCopy III Devices chapter in volume 1 of the

HardCopy III Device Handbook

■ External Memory Interfaces in HardCopy IV Devices chapter in volume 1 of the

HardCopy IV Device Handbook

■ External Memory Interfaces in Arria II GX Devices chapter in volume 1 of the Arria

II GX Device Handbook

■ External Memory Interfaces in Stratix IV Devices chapter in volume 1 of the Stratix IV

Device Handbook

■ External Memory Interfaces in Stratix III Devices chapter in volume 1 of the Stratix III

Device Handbook

1 The DQ/DQS read and write signals in Figure 4–1 may be bidirectional or

unidirectional, depending on the memory standard. When bidirectional, the signal is

active during both read and write operations.

Table 4–2 lists the megafunction blocks in Figure 4–1:

Table 4–1. Megafunction Blocks

Megafunction Block Description

ALTDLL The ALTDLL megafunction controls the DLL and DLL offset blocks. For more

information about the DLL blocks, refer to “ALTDLL Megafunction” on

page 4–3.

ALTDQ_DQS The ALTDQ_DQS megafunction controls the following memory interface

datapaths:

■ DQS Input Path

■ DQ Input Path

■ DQ Output/OE Path

■ DQS Output/OE Path

■ DQ/DQS OCT Path

For more information about the datapaths, refer to “ALTDQ_DQS

Megafunction” on page 4–4.

ALTPLL The ALTPLL megafunction block provides the clocking scheme used in the

custom external memory interface for half-rate or full-rate interface. For more

information about using PLLs, refer to the ALTPLL Megafunction User Guide.

ALTIOBUF The ALTIOBUF megafunction provides I/O buffer variations to connect the

ALTDQ_DQS instance to the FPGA pins and to support dynamic OCT feature.

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Altera ALTDLL Manual de usuario Pagina 38