Altera Stratix GX Transceiver - Manual (Page 49)

Altera Corporation 3–3
January 2005 Stratix GX Transceiver User Guide
Basic Mode
word alignment circuit that is used in conjunction with the pattern
detector to align the word boundary of the re-timed data to a specified
comma. In basic mode, this embedded circuit is configured to manual
alignment mode, which consists of 10-bit, 16-bit, and bit-slip modes.
The word aligner is composed of a pattern detector, manual alignment
controller, bit-slipper circuitry, and synchronization state machines.
Depending on the configuration, these components work in conjunction
or independently of one another. The word aligner cannot be bypassed,
but if the rx_enacdet signal is not used, the word aligner does not alter
the data.
Figure 3–3 shows the various components of the word aligner in
basic mode. The functionality is described in the following sections.
Figure 3–3. Components in the Stratix GX Word Aligner
Pattern Detector Module
The pattern detector matches a predefined comma to the current byte
boundary. If the comma is found, the optional rx_patterndetect
signal is asserted for the duration of one clock cycle to signify that the
comma exists in the current word boundary. The pattern detector module
only indicates that the signal exists and does not modify the word
boundary. Modification of the word boundary is discussed in the word
alignment and synchronization sections.
10-Bit
Mode
A1A2
Mode
7-Bit
Mode
16-Bit
Mode
Word Ali g ner
Pattern
Detector
10-Bit
Mode
Manual
Ali g nment Mode
Bit-Slip
Mode 16-Bit
Mode