Specifications
To enable cascaded decoding, the data paths fed by the rdinand
rdforceinputs are not pipelined. If these inputs are to be used in non-
cascaded decoders, they should be delayed by one clock cycle with
respect to their corresponding datainand kininputs.
Decoding Latency
The decoder is pipelined, thus it takes two clock cycles for a character to
be decoded. The decoded value—corresponding to the value of datain
sampled by the decoder on rising edge n—is output shortly after rising
edge n+1, and is available to be sampled on the rising edge of clock cycle
n+2. (See Figure 3–6 on page 3–7).
Figure 3–8. Decoder Timing Diagram
n
n+1 n+2 n+3
clk
a
b
a
c
a
b
d
b
c
e
c
f
g
e
f
datain, ena
dataout, kout
kerr, rdout, rderr
d
e
d
rdforce, rdin
OpenCore Plus Time-Out Behavior
OpenCore® Plus hardware evaluation can support the following two
modes of operation:
■
■
Untethered—the design runs for a limited time
Tethered—requires a connection between your board and the host
computer. If tethered mode is supported by all megafunctions in a
design, the device can operate for a longer time or indefinitely
All megafunctions in a device time out simultaneously when the most
restrictive evaluation time is reached. If there is more than one
megafunction in a design, a specific megafunction’s time-out behavior
may be masked by the time-out behavior of the other megafunctions.
1
For MegaCore functions, the untethered timeout is 1 hour; the
tethered timeout value is indefinite.
Altera Corporation
October 2007
MegaCore Version 7.2
3–9
8B10B Encoder/Decoder MegaCore Function User Guide
ALTERA [ ALTERA CORPORATION ]
