Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
3.15 Bit-Oriented Protocol Registers
TBOP_MODE[1:0] Transmit BOP mode—Enables the BOP transmitter and establishes priority of TBOP [addr
0A1] output in relation to TDL1 [addr 0AD] output. When TBOP messages are given output
priority, any write to TBOP aborts TDL1 output within the next 8 FDL bit times and suspends
TDL1 data output until TBOP has completed transmission. The processor can check TMSG1
status [addr 0AE] before writing TBOP to determine if TDL1 output is idle. The TDL1 buffer
can be written while TBOP is granted priority.
When TDL1 messages are given output priority, TBOP output is suspended when the TDL1
buffer becomes non-empty. In case of multiple pending messages, PRM messages have highest
priority, then BOP, and then TDL1. Furthermore, TBOP is forced to wait until the TDL1 buffer
is empty and the TDL1 output is in the idle state before TBOP output is granted priority. If
TBOP_LEN is continuous, and TDL1/PRM message output is pending, then TBOP is
suspended at the next 16-bit pattern boundary. TDL1 priority is used to transmit PRM, DS1
Idle (ISID), or optional path maintenance (PID, TSID) messages, which are separated by ESF
Yellow Alarm codewords, as defined in Annex D of ANSI T1.403.
TBOP_MODE
Mode Description
Disabled: TBOP writes are ignored
TBOP output priority
0X
10
11
TDL1 output priority
0A1—Transmit BOP Codeword (TBOP)
Writing a codeword into TBOP transmits a BOP message. The LSB is transmitted first.
7
6
5
4
3
2
1
0
—
—
TBOP[5]
TBOP[4]
TBOP[3]
TBOP[2]
TBOP[1]
TBOP[0]
TBOP[5]
Sixth bit transmitted
Fifth bit transmitted
Fourth bit transmitted
Third bit transmitted
Second bit transmitted
TBOP[4]
TBOP[3]
TBOP[2]
TBOP[1]
TBOP[0]
Transmit BOP codeword; first bit transmitted
N8370DSE
Conexant
3-89
CONEXANT [ CONEXANT SYSTEMS, INC ]
