PM7385 FREEDM-84A672
DATA SHEET
PMC-1990114
ISSUE 6
84 LINK, 672 CHANNEL FRAME ENGINE AND DATA LINK MANAGER
WITH ANY-PHY PACKET INTERFACE
SBI
SBI
RCAS
SBI
SBI
RCAS
Link
No.
SBI
SBI
RCAS
Link
No.
SPE Trib.
Link
No.
SPE Trib.
SPE Trib.
No.
1
No.
23
No.
2
No.
23
No.
3
No.
23
66
69
72
75
78
81
67
70
73
76
79
82
68
71
74
77
80
83
1
1
1
1
1
24
25
26
27
28
2
2
2
2
2
24
25
26
27
28
3
3
3
3
3
24
25
26
27
28
Links containing a T1/J1 or an E1 stream may be channelised. Data at each
time-slot may be independently assigned to a different channel. The RCAS672
performs a table lookup to associate the link and time-slot identity with a channel.
The position of T1/J1 and E1 framing bits/bytes is identified by frame pulse
signals generated by the SBI PISO blocks. Links containing a DS-3 stream are
unchannelised, i.e. all data on the link belongs to one channel. The RCAS672
performs a table lookup using only the link number to determine the associated
channel, as time-slots are non-existent in unchannelised links. Links may
additionally be configured to operate in an unframed “clear channel” mode, in
which all bit positions, including those normally reserved for framing information,
are assumed to be carrying HDLC data. Links so configured operate as
unchannelised regardless of link rate and the RCAS672 performs a table lookup
using only the link number to determine the associated channel.
8.4.1 Line Interface
There are 84 line interface blocks in the RCAS672. Each line interface block
contains a bit counter, an 8-bit shift register and a holding register that, together,
perform serial to parallel conversion. Whenever the holding register is updated,
a request for service is sent to the priority encoder block. When acknowledged
by the priority encoder, the line interface responds with the data residing in the
holding register.
To support channelised links, each line interface block contains a time-slot
counter. The time-slot counter is incremented each time the holding register is
updated and is reset on detection of a frame pulse from the SBI PISO blocks.
For unchannelised or unframed links, the time-slot counter is held reset.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
43
PMC [ PMC-SIERRA, INC ]
