DS258 Datasheet, PDF (6/12 Pages) Xilinx, Inc – Fully synchronous operation

8b/10b Decoder v7.1
active by default; to make the decoder(s) respond to the falling edge of a system clock, insert an inverter
between the system clock and the decoder's CLK input.
CLK_B is the clock input for the optional secondary B decoder.
Clock Enable - CE (CE_B)
CE, an optional input, can be used to stall the decoder, preventing it from responding to changes on the
inputs. If the decoder has a CE port and the CE input is inactive (logic 0), transitions on the clock port
will have no effect. If CE is active (logic 1) or is not present, the inputs will be read and outputs updated
on every rising edge of the CLK.
The CE_B pin is the Clock Enable for the B Decoder.
Data-Input Bus - DIN[9:0] (DIN_B[9:0])
DIN is the input bus that provides the 10-bit encoded symbol to the decoder. In the case of serial data
transmission, it is important to note that DIN(0) is the least-significant bit of the 10-bit encoded symbol.
DIN must be aligned on symbol boundaries (D<0>=a, D<9>=j) for the decoder to produce correct
results.
DIN_B is the data input bus for the B decoder.
Synchronous Initialization - SINIT (SINIT_B)
SINIT, an optional input, initializes the decoder to a defined state. If SINIT is active (logic 1) and CE is
active, the outputs and internal state of the decoder will be set on the rising edge of the clock. In this
case, DOUT will be set to a user-defined value, KERR will be set to zero, and the internal running dis-
parity will be set to a user-defined value. It is recommended to assert SINIT at times when the decoder's
state must be known, such as before receiving a packet, to insure that the running disparity is initialized
correctly before receiving.
SINIT_B is the synchronous initialization input for the B decoder.
Data-Output Bus - DOUT (DOUT_B)
DOUT is the decoded output byte. Subsequent to every rising clock edge (provided that CE is not
present and inactive), DOUT will hold the decoded data byte. The decoded data byte is the decoded
value of the 10-bit symbol on the DIN bus at the clock edge.
DOUT_B is the decoded byte output for the B decoder.
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DS258 April 28, 2005
Product Specification