CX28394/28395/28398
2.0 Circuit Description
Quad/x16/Octal—T1/E1/J1 Framers
2.3 System Bus
Figure 2-19. Transmit Framing and Timebase Alignment Options
TSLIP
Buffer
TNRZ
TPCMI
TPHASE
CAS
MFAS
On-Line On-Line
Recenter
(TUSLIP)
0 1
A
C
Off-Line
Framer
TFSYNCI
Pass
MF
TMSYNCI
B
D
TSB
Offset
TFSYNCO
TMSYNCO
FSYNC FAS CAS MSYNC
TX Timebase
FSYNC MSYNC
TSB Timebase
Pass
MF
TSB Aligns to TNRZ (EMBED = 1)
TX Aligns to TSB (TX_ALIGN = 1)
C
D
TSB Aligns to TPCMI (EMBED = 0)
TSB Aligns to TX (TSB_ALIGN = 1)
A
B
NOTE(S):
(1)
EMBED located in SBI_CR (addr 0D0).
TSB_ALIGN and TX_ALIGN located in TSB_CR (addr 0D4).
(2)
When TLOF is asserted, the offline framer searches the transmit data stream
for a new frame alignment, provided that transmit framing is enabled [TABORT;
addr 071]. If embedded framing is enabled [EMBED; addr 0D0], the offline
framer examines the TSLIP buffer output—TNRZ—for transmit frame
alignment. If embedded framing is disabled, the offline framer examines the slip
buffer input (TPCMI) for transmit frame alignment. This case (EMBED = 0) is
only applicable if TPCMI is configured to operate at the line rate—2,048 kbps
E1, or 1,544 kbps T1. If transmit framing is disabled, the offline framer waits for
a reframe command [TFORCE; addr 071] before beginning a frame alignment
search.
Transmit Multiframe
Alignment
After the offline framer recovers frame alignment, the online framer monitors
TLOF and searches for multiframe alignment using criteria defined by the
Transmit Frame mode [TFRAME; addr 070]. The online framer conducts a
multiframe alignment search each time the offline framer recovers transmit frame
alignment—as reported by high-to-low transition of transmit loss of frame status
[TLOF; addr 048]. After TLOF recovery, the online framer searches continuously
for multiframe alignment until the correct pattern sequence is located, or until
basic frame alignment is lost (TLOF goes active-high). After multiframe
alignment recovery, the online framer checks subsequent multiframes for errored
alignment patterns, but does not use those errors as part of the criteria for loss of
basic frame alignment.
100054E
Conexant
2-37
CONEXANT [ CONEXANT SYSTEMS, INC ]
