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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
286
25, the quiescent period is shown to be a low level on TCLK[n]. A high level,
effected by extending the high phase of the previous valid bit, is also acceptable.
Gapping of TCLK[n] can occur arbitrarily without regard to byte nor frame
boundaries.
Figure 25 – Unchannelised Transmit Link Timing
TCLK[n]
TD[n]
B1 B2 B3 B4
B5
B6
B7 B8 B1
B2
The timing relationship of the transmit clock (TCLK[n]) and data (TD[n]) signals
of a channelised T1 link is shown in Figure 26. The transmit data stream is a T1
frame with a single framing bit (F in Figure 26) followed by octet bound time-slots
1 to 24. TCLK[n] is held quiescent during the framing bit. The most significant
bit of each time-slot is transmitted first (B1 in Figure 26). The least significant bit
of each time-slot is transmitted last (B8 in Figure 26). The TD[n] bit (B8 of TS24)
before the framing bit is the least significant bit of time-slot 24. In Figure 26, the
quiescent period is shown to be a low level on TCLK[n]. A high level, effected by
extending the high phase of bit B8 of time-slot TS24, is equally acceptable. In
channelised T1 mode, TCLK[n] can only be gapped during the framing bit. It
must be active continuously at 1.544MHz during all time-slot bits. Time-slots that
are not provisioned to belong to any channel (PROV bit in the corresponding
word of the transmit channel provision RAM in the TCAS block set low) transmit
the contents of the Idle Fill Time-slot Data register.
Figure 26 – Channelised T1 Transmit Link Timing
TCLK[n]
TD[n]
B7 B8
B1
B2 B3 B4 B5 B6 B7 B8 B1 B2 B3
TS 24
TS 1
TS 2
F
The timing relationship of the transmit clock (TCLK[n]) and data (TD[n]) signals
of a channelised E1 link is shown in Figure 27. The transmit data stream is an
E1 frame with a singe framing byte (FAS/NFAS in Figure 27) followed by octet
bound time-slots 1 to 31. TCLK[n] is held quiescent during the framing byte.
The most significant bit of each time-slot is transmitted first (B1 in Figure 27).
The least significant bit of each time-slot is transmitted last (B8 in Figure 27).
The TD[n] bit (B8 of TS31) before the framing byte is the least significant bit of
time-slot 31. In Figure 27, the quiescent period is shown to be a low level on