Altera 8B10B Encoder/Decoder MegaCore Function - Manual (Page 27)

Chapter 3: Specifications 3–9
Signals
May 2011 Altera Corporation 8B10B Encoder/Decoder MegaCore Function User Guide
Decoder Signals
Table 3–4 show the decoder signals.
Table 3–4. Decoder Signals
Signal Name Direction Description
clk Input
Clock. The input is latched, and the result output on this clock. There is a one clock
cycle latency between the input and output.
reset_n Input
Active low, reset. Asynchronously resets all registers in the MegaCore function. This
signal must be deasserted synchronously to the rising edge of
clk .
idle_del Input
Idle delete signal. When high, idle words (K28.5) are removed from the stream (i.e.
valid is set low when idle words are received).
ena Input
Enable decoder signal. When high, indicates that the data currently present on the
datain input is to be decoded.
datain[9:0] Input Data input. This is the 10-bit encoded input word.
rdin Input
Running disparity input. When rdforce is high, the value on this pin is used as the
current running disparity instead of the internally generated one.
rdforce Input
Force running disparity. When high, the rdin value overrides the internally generated
running disparity.
valid Output
Valid signal. This signal is asserted when ena is asserted and new, non-idle data is
present on dataout , even if it is the result of an illegal codeword. If an illegal
codeword is received, kerr is also asserted.
valid is also asserted for idle characters (K28.5) when ena is asserted and idle_del
is not asserted.
dataout[7:0] Output Data output. This is the 8-bit decoded data or command.
kout Output
Command output. When high, indicates that the output is a command byte, not a data
byte.
kerr Output
Special K error. Asserted high when an invalid 10-bit word is received, or when a
10B_ERR character is received.
rderr Output
Running disparity error. When high indicates the running disparity rules have been
violated.
rdout Output
Running disparity output. The current running disparity (after decoding the word
present on the
dataout output).
rdcascade Output Cascaded running disparity. Used when decoders are cascaded.