Altera DQ (ALTDQ) Manual do Utilizador descarregar pdf (Página 8)

Page 8 Getting Started

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

How many valid half cycles of the

inclk input should pass before the

DLL simulates a lock?

Only affects simulation and has no affect on actual

device operation. Use to reduce number of clock

cycles for which a simulation must be run before the

DLL locks. By setting this to 1, the DLL immediately

locks and simulation can begin transferring data.

No No Yes Yes

How many invalid half clock cycles

of the inclk input should pass

before the DLL simulates a loss of

lock? (2)

Only affects simulation and has no affect on actual

device operation. Use to reduce number of clock

cycles for which a simulation must be run before the

DLL locks. By setting this to 1, the DLL immediately

locks and simulation can begin transferring data.

No No Yes Yes

Notes to Table 3:

(1) Low/high refers to jitter mode. The DLL in Stratix II device DQS phase-shift circuitry can operate between 100 and 300 MHz in either fast lock

mode or low jitter mode. Fast lock mode requires fewer clock cycles to calculate the input clock period, but the low jitter mode is more accurate.

The DQS delay settings (the up/down counter output) are updated every eight clock cycles. If the low jitter mode is enabled, the phase

comparator also issues a clock-enable signal to the up/down counter notifying the counter when to update the DQS settings. In low jitter mode,

the enable signal is only active when the

upndn

signal is incremented or decremented by 4, otherwise the clock-enable is off and the DQS delay

settings do not get updated. This enable signal is always active if the DLL is in fast lock mode.

(2) Stratix II devices do not support this feature, and the option is disabled in the MegaWizard Plug-In Manager for these devices.

Table 3. General 2 Settings (Part 2 of 2)

Option Description

Supported Devices

Cyclone II

Cyclone III, Cyclone IV GX

Stratix, Stratix GX,

Stratix II, Stratix II GX, Arria GX, HardCopy II

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 30 31

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Altera DQ (ALTDQ) Manual do Utilizador Página 8