
DATA SHEET
PM7367 FREEDM-32P32
ISSUE 2
PMC-1991499
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMER’S INTERNAL USE
118
E1 framing bytes. The data bit on RD[0] clocked in by the first rising edge of
RCLK[0] after an extended quiescent period is considered to be the most
significant bit of time-slot 1. When CEN is set low, receive link #0 is
unchannelised. The E1 register bit is ignored. RCLK[0] is gapped during
non-data bytes. The choice between treating all data bits as a contiguous
stream with arbitrary byte alignment or byte aligned to gaps in RCLK[0] is
controlled by the BSYNC bit.
E1:
The E1 frame structure select bit (E1) configures receive link #0 for
channelised E1 operation when CEN is set high. RCLK[0] is held quiescent
during the FAS and NFAS framing bytes. The data bit on RD[0] associated
with the first rising edge of RCLK[0] after an extended quiescent period is
considered to be the most significant bit of time-slot 1. Link data is present at
time-slots 1 to 31. When E1 is set low and CEN is set high, receive link #0 is
configured for channelised T1 operation. RCLK[0] is held quiescent during
the framing bit. The data bit on RD[0] associated with the first rising edge of
RCLK[0] after an extended quiescent period is considered to be the most
significant bit of time-slot 1. Link data is present at time-slots 1 to 24. E1 is
ignored when CEN is set low.
BSYNC:
The byte synchronisation enable bit (BSYNC) controls the interpretation of
gaps in RCLK[0] when link #0 is in unchannelised mode (CEN set low).
When BSYNC is set high, the data bit on RD[0] clocked in by the first rising
edge of RCLK[0] after an extended quiescent period is considered to be the
most significant bit of a data byte. When BSYNC is set low, gaps in RCLK[0]
carry no special significance. BSYNC is ignore when CEN is set high.