XRT73L03B Datasheet, PDF (44/61 Pages) Exar Corporation – 3 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT

XRT73L03B
3 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
REV. 1.0.1
If the XRT73L03B is operating in the HOST Mode,
monitored by reading in the contents of Command
the state of ALOS_(n) of Channel(n) can be polled or Register CR0. .
COMMAND REGISTER CR0-(n)
D4
D3
D2
D1
D0
RLOL_(n)
RLOS_(n)
ALOS_(n)
DLOS_(n)
DMO_(n)
Read Only
Read Only
Read Only
Read Only
Read Only
If the ALOS_(n) bit-field contains a "1", then the cor-
responding Channel(n) is currently declaring an
ALOS condition. Conversely, if the ALOS_(n) bit-field
contains a "0", then the channel is not currently de-
claring an ALOS condition.
For debugging purposes, it may be useful to disable
the ALOS Detector. If the XRT73L03B is operating in
the HOST Mode, disable the Channel(n) ALOS De-
tector by writing a "1" into the ALOSDIS_(n) bit-field
in Command Register CR2.
Disabling the ALOS Detector
COMMAND REGISTER CR2-(n)
D4
D3
D2
D1
D0
Reserved
ENDECDIS_(n)
ALOSDIS_(n)
DLOSDIS_(n)
REQEN_(n)
X
X
1
X
X
2. The Digital LOS (DLOS) Declaration/Clearance
Criteria
COMMAND REGISTER CR0-(n)
A given channel(n) declares a Digital LOS
(DLOS_(n)) condition if the XRT73L03B detects
160±32 or more consecutive "0’s" in the incoming da-
ta.
The channel clears DLOS if it detects four consecu-
tive sets of 32 bit-periods, each of which contains at
least 10 "1’s" (e.g., average pulse density of greater
than 33%).
Monitoring the State of DLOS
D4
D3
D2
D1
D0
RLOL_(n) RLOS_(n) ALOS_(n) DLOS_(n) DMO_(n)
Read Only Read Only Read Only Read Only Read Only
If the DLOS_(n) bit-field contains a “1”, then the cor-
responding channel(n) is currently declaring a DLOS
condition. Conversely, if the DLOS_(n) bit-field con-
tains a “0”, then the channel(n) is currently declaring
the DLOS condition.
If the XRT73L03B is operating in the HOST Mode the
state of DLOS_(n) of Channel(n) can be polled or
monitored by reading in the contents of Command
Register CR0.
Disabling the DLOS Detector
For debugging purposes, it is useful to disable the
DLOS_(n) detector. If the XRT73L03B is operating in
the HOST Mode, the DLOS Detector can be disabled
by writing a “1” into the DLOSDIS_(n) bit-field in Com-
mand Register CR2.
COMMAND REGISTER CR2-(n)
D4
D3
D2
D1
D0
Reserved
ENDECDIS_(n)
ALOSDIS(n)
DLOSDIS(n)
REQEN(n)
X
X
X
1
X
NOTE: Setting both the ALOSDIS_(n) and DLOSDIS_(n)
bit-fields to "1" disables LOS Declaration by Channel(n).
3.5.3 Muting the Recovered Data while the LOS
is being Declared
In some applications it is not desirable for a channel
within the E3/DS3/STS-1 LIU to recover data and
route it to the Receiving Terminal while the channel is
declaring an LOS condition. Consequently, the
XRT73L03B includes an LOS Muting feature. This
feature, if enabled, causes a given channel to halt
transmission of the recovered data to the Receiving
Terminal while the LOS condition is "true". In this
case, the RPOS_(n) and RNEG_(n) output pins are
42