RELEASED
PM7383 FREEDM-32A256
DATASHEET
PMC-2010336
ISSUE 1
FRAME ENGINE AND DATA LINK MANAGER 32A256
Figure 17 – Channelised T1/J1 Receive Link Timing
RCLK[n]
B7 B8 F B1 B2 B3 B4 B5 B6 B7 B8 B1 B2 B3
RD[n]
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 18. The receive data stream is an E1
frame with a singe framing byte (F1 to F8 in Figure 18) 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 18, 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
RCAS256 block to low.
Figure 18 – Channelised E1 Receive Link Timing
RCLK[n]
B8
B1 B2 B3 B4 B5 B6 B7 B8 B1 B2 B3 B4
RD[n]
B6 B7
TS 31
F1 F2 F3 F4 F5 F6 F7 F8
FAS / NFAS
TS 1
TS 2
12.4 Transmit non H-MVIP Link Timing
The timing relationship of the transmit clock (TCLK[n]) and data (TD[n]) signals of
a unchannelised link is shown in Figure 19. 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 19)
and ending with the least significant bit (B8 in Figure 19). Bits are updated on
the falling edge of TCLK[n]. A transmit link may be stalled by holding the
PROPRIETARY AND CONFIDENTIAL
191
PMC [ PMC-SIERRA, INC ]
