DS21Q58 E1 Quad Transceiver
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8.3 Automatic Alarm Generation
The device can be programmed to automatically transmit AIS or remote alarm. When automatic AIS generation is
enabled (CCR2.5 = 1), the device monitors the receive framer to determine if any of the following conditions are
present: loss-of-receive frame synchronization, AIS alarm (all ones) reception, or loss-of-receive carrier (or signal).
If one (or more) of these conditions is present, the framer forces an AIS alarm.
When automatic RAI generation is enabled (CCR2.4 = 1), the receiver is monitored to determine if any of the
following conditions are present: loss-of-receive frame synchronization, AIS alarm (all ones) reception, or loss-of-
receive carrier (or signal), or if CRC4 multiframe synchronization cannot be found within 128ms of FAS
synchronization (if CRC4 is enabled). If one (or more) of these conditions is present, the device transmits an RAI
alarm. RAI generation conforms to ETS 300 011 specifications, and a constant remote alarm is transmitted if the
DS21Q58 cannot find CRC4 multiframe synchronization within 400ms as per G.706.
Register Name:
CCR3
Register Description:
Common Control Register
Register Address:
14 Hex
Bit #
7
6
5
4
Name
RLB
LLB
LIAIS
TCM4
TCM3
NAME
BIT
FUNCTION
Remote Loopback.
See Section
8.4
for details.
0 = loopback disabled
1 = loopback enabled
Local Loopback.
See Section
8.5
for details.
0 = loopback disabled
1 = loopback enabled
Line Interface AIS-Generation Enable
0 = allow normal data to be transmitted at TTIP and TRING
1 = force unframed all ones to be transmitted at TTIP and TRING at the
MCLK rate
Transmit Channel Monitor Bit 4
. MSB of a channel decode that
determines which transmit channel data appears in the TDS0M register.
See Section
10
or details.
TCM3
3
Transmit Channel Monitor Bit 3
TCM2
2
Transmit Channel Monitor Bit 2
TCM1
1
Transmit Channel Monitor Bit 1
TCM0
0
Transmit Channel Monitor Bit 0.
LSB of the channel decode.
3
2
1
0
TCM2
TCM1
TCM0
RLB
7
LLB
6
LIAIS
5
TCM4
4
8.4 Remote Loopback
When CCR4.7 is set to 1, the DS21Q58 is forced into remote loopback (RLB) mode. In this loopback, data input
through the RPOSI and RNEGI pins is transmitted back to the TPOSO and TNEGO pins. Data continues to pass
through the DS21Q58’s receive framer as it would normally and the data from the transmit formatter is ignored
(
Figure 3-1
).