EP4CE30F29C7N Datasheet, PDF (297/488 Pages) Altera Corporation – Cyclone IV Device Handbook, Volume 1

Chapter 1: Cyclone IV Transceivers Architecture
Receiver Channel Datapath
1–17
Word Aligner
Figure 1–16 shows the word aligner block diagram. The word aligner receives parallel
data from the deserializer and restores the word boundary based on a pre-defined
alignment pattern that must be received during link synchronization. The word
aligner supports three operational modes as listed in Table 1–3.
Figure 1–16. Word Aligner Block Diagram
Word Aligner
data from
deserializer
rx_enapatternalign
rx_bitslip
rx_invpolarity
rx_revbitorderwa
Receiver
Polarity
Inversion
Bit-Slip
Circuitry
Synchronization
State Machine
Manual
Alignment
Run Length
Violation
Receiver
Bit
Reversal
parallel data to
next PCS block
rx_bitslipboundaryselectout
rx_rlv
rx_syncstatus
rx_patterndetect
Table 1–3. Word Aligner Modes
Modes
Manual Alignment
Bit-Slip
Automatic Synchronization State
Machine
PMA-PCS Interface Widths
Allowed Word Alignment
Pattern Lengths
8-bit
16 bits
10-bit
7 or 10 bits
8-bit
16 bits
10-bit
7 or 10 bits
10-bit
7 or 10 bits
Manual Alignment Mode
In manual alignment mode, the rx_enapatternalign port controls the word aligner
with either an 8- or 10-bit data width setting.
The 8-bit word aligner is edge-sensitive to the rx_enapatternalign signal. A rising
edge on rx_enapatternalign signal after deassertion of the rx_digitalreset signal
triggers the word aligner to look for the word alignment pattern in the received data
stream. It updates the word boundary if it finds the word alignment pattern in a new
word boundary. Any word alignment pattern received thereafter in a different word
boundary causes the word aligner to re-align to the new word boundary only if there
is a rising edge in the rx_enapatternalign signal.
The 10-bit word aligner is level-sensitive to the rx_enapatternalign signal. The word
aligner looks for the programmed 7-bit or 10-bit word alignment pattern or its
complement in the received data stream, if the rx_enapatternalign signal is held
high. It updates the word boundary if it finds the word alignment pattern in a new
word boundary. If the rx_enapatternalign signal is deasserted, the word aligner
maintains the current word boundary even when it receives the word alignment
pattern in a new word boundary.
October 2013 Altera Corporation
Cyclone IV Device Handbook,
Volume 2