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____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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programmable (1 to 32, y < n) in the
BPCR register. The output of the Rx pattern generator is the feedback. If
QRSS is enabled (
BPCR.QRSS=1) is enabled, the feedback is an XOR of bits 17 and 20, and the output is forced
to one if the next 14 bits are all zeros. For PRBS and QRSS patterns, the feedback is forced to one if bits 1 through
31 are all zeros. Depending on the type of pattern programmed, pattern detection performs either PRBS
synchronization or repetitive pattern synchronization.
10.14.4.1 Rx PRBS Synchronization
PRBS synchronization synchronizes the Rx pattern generator to the incoming PRBS or QRSS pattern. The Rx
pattern generator is synchronized by loading 32 data stream bits into the Rx pattern generator, and then checking
the next 32 data stream bits. Synchronization is achieved if all 32 bits match the incoming pattern. If at least six
incoming bits in the current 64-bit window do not match the Rx pattern generator, automatic pattern re-
synchronization is initiated. Automatic pattern resynchronization can be disabled by setting
BCR:APRD=1. Pattern
resynchronization can also be initiated manually by a zero-to-one transition of the Manual Pattern
Resynchronization bit
(BCR:MPR). The incoming data stream can be inverted before comparison with the Rx
pattern generator by setting
BCR:RPIC. See
Figure 10-79 for the PRBS synchronization state diagram.
Figure 10-79. PRBS Synchronization State Diagram
10.14.4.2 Rx Repetitive Pattern Synchronization
Repetitive pattern synchronization synchronizes the Rx pattern generator to the incoming repetitive pattern. The Rx
pattern generator is synchronized by searching each incoming data stream bit position for the repetitive pattern,
and then checking the next 32 data stream bits. Synchronization is achieved if all 32 bits match the incoming
pattern. If at least six incoming bits in the current 64-bit window do not match the Rx PRBS pattern generator,
automatic pattern re-synchronization is initiated. Automatic pattern resynchronization can be disabled by setting
BCR:APRD=1. Pattern resynchronization can also be initiated manually by a zero-to-one transition of the Manual
Pattern Resynchronization bit
(BCR:MPR). The incoming data stream can be inverted before comparison with the
Rx pattern generator by setting
BCR:RPIC. See
Figure 10-80 for the repetitive pattern synchronization state
diagram.
Sync
Load
Verify
1 bit error
32 bits loaded
32 bits without errors
6 of 64 bits with errors