Bt8370/8375/8376
3.0 Registers
Fully Integrated T1/E1 Framer and Line Interface
3.6 Primary Control and Status Registers
RFSYNC_IO
Bidirectional RFSYNC Input/Output mode—Refer to system bus sync mode summary in
Tables 3-6 and 3-8. When RFSYNC is an input, its low-to-high transition aligns the RSB
timebase to the programmed RSB.OFFSET. Refer to RSYNC_BIT, RSYNC_TS and
RSYNC_FRM offset registers [addr 0D2, 0D3, and 0D8] for a complete description of the
RSB sync bit, time slot, and frame offset. Once aligned, the RSB timebase internally flywheels
at 125 µs interval (8 kHz) until a new RFSYNC pulse is applied. When RFSYNC is
programmed as an output, it operates continuously at 8 kHz frame rate, marking RSB sync bits
and time slot offset position of each frame. Initial RFSYNC alignment and subsequent
realignment depends RSB mode [RSBI; addr 0D1] and RSB manual center [RSB_CTR; addr
0D1]. RFSYNC must be programmed as an output when RSLIP is in Bypass mode or Elastic
mode. RFSYNC and RMSYNC are supplied either by RSB timebase (output) or receive
system bus (input) at a programmable RSB sync bit offset, time slot location, and frame offset
location.
0 = RFSYNC input
1 = RFSYNC output
RMSYNC_IO
Bidirectional RMSYNC Input/Output mode—Refer to system bus sync mode summary in
Tables 3-6 and 3-8. When RMSYNC is an input, its low-to-high transition aligns RSB
timebase to the programmed RSB.OFFSET. Once aligned, RSB timebase internally flywheels
at 3 ms (T1) or at 2 ms (E1) intervals until a new RMSYNC pulse is applied.
When RMSYNC is an output, it operates continuously at a 6 ms rate (every second
multiframe for T1 or every third for E1), marking the RSB.OFFSET position. Initial
RMSYNC alignment and subsequent realignment depends on RSB mode [RSBI; addr 0D1]
and RSB manual center [RSB_CTR; addr 0D1]. RMSYNC must be programmed as an output
when RSLIP is in Bypass mode or Elastic mode. THRU bit must be set [THRU; addr 0D7]
when RMSYNC is programmed as an output. RMSYNC input signal must always coincide
with RFSYNC.
0 = RMSYNC input
1 = RMSYNC output
TFSYNC_IO
TMSYNC_IO
Bidirectional TFSYNC Input/Output mode—TFSYNC_IO programming depends on transmit
framer and system bus modes, as shown in Tables 3-6 and 3-7.
0 = TFSYNC input
1 = TFSYNC output
Bidirectional TMSYNC Input/Output mode—TMSYNC_IO programming depends on
transmit framer and system bus modes, as shown in Tables 3-6 and 3-7.
0 = TMSYNC input
1 = TMSYNC output
Table 3-6. System Bus Sync Mode Summary
FSYNC
MSYNC
SBI Alignment Mode
IN
IN
SBI supplies multiframe and 8 kHz frame alignment. FSYNC must be aligned with
MSYNC if both are provided.
IN
IN-GND
SBI supplies 8 kHz frame alignment. Multiframe alignment is arbitrary and MSYNC is
unused.
IN
IN-GND
OUT
OUT
OUT
IN
SBI supplies 8 kHz frame alignment. Multiframe alignment is supplied by the framer.
Framer supplies multiframe alignment. FSYNC is unused.
SBI supplies multiframe and frame alignment.
OUT
OUT
Framer supplies frame and multiframe alignment.
N8370DSE
Conexant
3-33
CONEXANT [ CONEXANT SYSTEMS, INC ]
