
XRT79L71
PRELIMINARY
347
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
STEP 2 - Configure the Transmit Drive Monitor block into the "External" Mode.
This is accomplished by setting Bit 5 (Internal Transmit Drive Monitor) to "0" as depicted below.
Once the user has implemented both of these steps, then the Transmit Drive Monitor block will proceed to
check the TTIP/TRING lines for "bipolar activity" via the "MTIP" and "MRING" input pins. As long as the
Transmit Drive Monitor block detects a regular stream of bipolar pulses via the MTIP/MRING pins, then it will
negate the "Transmit DMO Condition" by continuing to set Bit 0 (Transmit DMO Condition), within the "LIU
Alarm Status" Register, to "0" as depicted below.
NOTE: For most applications, the "Transmit DMO Condition" bit-field being set to "0" is a normal and a desirable condition.
However, if the Transmit Drive Monitor block ever fails to detect any bipolar pulses (via the MTIP/MRING input
pins) for approximately 128 bit periods, then the XRT79L71 will declare the "Transmit Drive Monitor" defect
condition. Whenever the XRT79L71 declares the "Transmit Drive Monitor" defect condition, then it will do all of
the following.
1.
It will set Bit 0 (Transmit DMO Condition), within the "LIU Alarm Status" Register, to "1" as depicted
below.
LIU Transmit Control Register (Address = 0x1304)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Internal
Transmit
Drive Monitor
Unused
TAOS
Unused
TxLEV
R/O
R/W
R/O
R/W
R/O
R/W
0
LIU Alarm Status Register (Address = 0x1303)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Digital
LOS
Defect
Declared
Analog
LOS
Defect
Declared
FL
(FIFO Limit)
Alarm
Declared
Receive
LOL Defect
Declared
Receive
LOS Defect
Declared -
Receive
DS3/E3 LIU
Block
Transmit
DMO
Condition
R/O
0