IPR-ED8B10B Altera, IPR-ED8B10B Datasheet - Page 25

• Manufacturer Part Number: IPR-ED8B10B
• Description: IP CORE Renewal Of IP-ED8B10B
• Manufacturer: Altera
• Type: MegaCorer

Specifications of IPR-ED8B10B

• Software Application: IP CORE, Interface And Protocols, COMMUNICATION
• Supported Families: Arria GX, Cyclone, HardCopy, Stratix
• Core Architecture: FPGA
• Core Sub-architecture: Arria, Cyclone, Stratix
• Rohs Compliant: NA
• Function: Encoder/Decoder, 8b/10b for Gigabit Ethernet and Fibre Channel
• License: Renewal License
• Lead Free Status / RoHS Status: na
• Lead Free Status / RoHS Status: na

Chapter 3: Specifications
Functional Description
© November 2009 Altera Corporation
Figure 3–7
Figure 3–7. Decoder
Cascaded Decoding
Two decoders can be cascaded to decode two words simultaneously. The decoders are
cascaded—in a similar fashion as the encoders—by connecting the rdcascade
output of the first decoder to the rdin input of the second decoder, and by connecting
the rdout output of the second decoder to the rdin input of the first decoder. The
rdforce inputs of both decoders must be tied high.
To enable cascaded decoding, the data paths fed by the rdin and rdforce inputs 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 datain and kin
inputs.
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 3–8. Decoder Timing Diagram
shows a block diagram of the decoder.
kerr, rdout, rderr
dataout, kout
rdforce, rdin
datain [9:0]
datain, ena
idle_del
reset_n
rdforce
ena
rdin
clk
Preliminary
clk
a
n
b
a
n+1
c
a
b
n+2 n+3
8B10B Encoder/Decoder MegaCore Function User Guide
d
b
c
c
e
d
Figure 3–6 on page
f
d
e
valid
dataout [7:0]
kout
kerr
rderr
rdout
rdcascade
g
f
e
3–6).
3–7