Achronix Speedster22i User Macro Guide Manual do Utilizador descarregar pdf (Página 49)

I/O Cells OPAD_D2

Speedster Macro Cell Library

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OPAD_D2

DDR Output Pad with Asynchronous or Synchronous Set/Reset

rstn

pad

OPAD_D2

rstn

dina

dinb

data_en

clk

Figure 1-16: OPAD_D2 Logic Symbol

OPAD_D2isaDoubl

eDataRate(DDR)outputpadwithactive‐highregisteredoutputenable.

Thereisanadditionalstageofregistersontheoutputstoallowthelogiclevelonthepadto

changesonboththerisingandfallingedgesoftheclock,butallowtheinterfacesignalstothe

GA core to change on the rising edge of the clock.This additional level of registers

providesafullcycletogetintoandoutoftheFPGAcore.

Table 1-37: Ports

Name Type Description

pad Device output pad.

dina

Positive-edge based data input. Data is

clocked into the dina register upon

the rising edge of the txclk input when the txdata_en signal is high. It is

routed to the pad on the following rising edge of the clock. If the oe input

was high during the same clock period of the dina input, the pad will be

actively driven with the dina data during the portion of the clock period

when txclk is high.

dinb

Negative-edge based data input. Data is

clocked into the dinb register

upon the falling edge of the txclk input when the txdata_en signal is high. It

is routed to the pad on the following rising edge of the clock. If the oe input

was high during the same clock period of the dinb input, the pad will be

actively driven with the dinb data during the portion of the clock period

when txclk is low.

data_en

Transmit Data Enable (

active-high). A high value on data_en enables the

dina and dinb inputs to be clocked into the transmit registers.

rstn

Asynchronous Reset input. A l

ow value on rstn performs an asynchronous

initialization of the Output Register if the rstmode parameter is set to “async”.

The value initialized into the Output Register is determined by the value of

the rstvalue parameter.

clk Clock Input.

output

input

1 2 ... 44 45 46 47 48 49 50 51 52 53 54 ... 223 224

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