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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
285
Figure 23 – Channelised T1 Receive Link Timing
RCLK[n]
RD[n]
B7 B8 F B1 B2 B3 B4 B5 B6 B7 B8 B1 B2 B3
TS 24
TS 1
TS 2
The timing relationship of the receive clock (RCLK[n]) and data (RD[n]) signals of
a channelised E1 link is shown in Figure 24. The receive data stream is an E1
frame with a singe framing byte (F1 to F8 in Figure 24) followed by octet bound
time-slots 1 to 31. RCLK[n] is held quiescent during the framing byte. The RD[n]
data bit (B1 of TS1) clocked in by the first rising edge of RCLK[n] after the
framing byte is the most significant bit of time-slot 1. The RD[n] bit (B8 of TS31)
clocked in by the last rising edge of RLCLK[n] before the framing byte is the least
significant bit of time-slot 31. In Figure 24, the quiescent period is shown to be a
low level on RCLK[n]. A high level, effected by extending the high phase of bit
B8 of time-slot TS31, is equally acceptable. In channelised E1 mode, RCLK[n]
can only be gapped during the framing byte. It must be active continuously at
2.048 MHz during all time-slot bits. Time-slots can be ignored by setting the
PROV bit in the corresponding word of the receive channel provision RAM in the
RCAS block to low.
Figure 24 – Channelised E1 Receive Link Timing
RCLK[n]
RD[n]
B6 B7
F1 F2 F3 F4 F5 F6 F7 F8B1 B2 B3
TS 31
FAS / NFAS
TS 1
B8
B4 B5 B6 B7 B8 B1 B2 B3 B4
TS 2
13.2 Transmit Link Output Timing
The timing relationship of the transmit clock (TCLK[n]) and data (TD[n]) signals
of a unchannelised link is shown in Figure 25. The transmit data is viewed as a
contiguous serial stream. There is no concept of time-slots in an unchannelised
link. Every eight bits are grouped together into a byte with arbitrary byte
alignment. Octet data is transmitted from most significant bit (B1 in Figure 25)
and ending with the least significant bit (B8 in Figure 25). Bits are updated on
the falling edge of TCLK[n]. A transmit link may be stalled by holding the
corresponding TCLK[n] quiescent. In Figure 25, bits B5 and B2 are shown to be
stalled for one cycle while bit B6 is shown to be stalled for three cycles. In Figure