Altera LVDS SERDES Manual do Utilizador descarregar pdf (Página 5)

DPA FIFO

In DPA-FIFO mode, the DPA FIFO synchronizes the retimed data to the high-speed LVDS clock domain.

Because the DPA clock may shift phase during the initial lock period, the FIFO must be held in reset state

until the DPA locks; otherwise, there may be a data run-through condition due to the FIFO write pointer

creeping up to the read pointer.

Bitslip

Use bitslip circuitry to insert latencies in increments of one fclk cycle for data word alignment. The data

slips one bit for every pulse of the rx_bitslip_ctrl signal. You must wait at least five core clock cycles

before checking if the data is aligned because it will take at least two core clock cycles to purge the undefined

data.

When enough bitslip signals are sent to rollover the bitslip counter, the rx_bitslip_max status signal is

asserted after five core clock cycles to indicate that it has reached its maximum counter value of the bitslip

counter rollover point.

Deserializer

The deserializer consists of shift registers. The deserialization factor determines the depth of the shift registers.

The loaden signal is a pulse with a frequency of the fclk divided by the deserialization factor. The

deserializer converts a 1-bit serial data stream into a parallel data stream based on the deserialization factor.

Figure 3: LVDS x8 Deserializer Waveform

7 6 5 4 3 2 1 0 a b c d e f g h A B C D E F G H X X X X X

X X X

ABCDEFGHabcdefgh76543210XXXXXXXX

RX_IN

FCLK

LOADEN

RX_OUT[7:0]

DescriptionSignal

LVDS data stream, input to the Altera LVDS SERDES channel.rx_in

Clock used for receiver.fclk

Enable signal for deserialization.loaden

Deserialized data.rx_out[7:0]

Initialization and Reset

This section describes the initialization and reset aspects, using control characters. This section also provides

a recommended initialization and reset flow for the Altera LVDS SERDES IP core.

Altera Corporation

Altera LVDS SERDES IP Core User Guide

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DPA FIFO

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2014.08.18

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Altera LVDS SERDES Manual do Utilizador Página 5