ds2156gn Maxim Integrated Products, Inc., ds2156gn Datasheet - Page 58

• Manufacturer Part Number: ds2156gn
• Description: Ds2156, Ds2156l, Ds2156ln T1/e1/j1 Single-chip Transceiver Tdm/utopia Ii Interface
• Manufacturer: Maxim Integrated Products, Inc.

8.2
The software signaling insertion-enable registers, SSIE1–SSIE4, can be used to select signaling insertion
from the transmit signaling registers, TS1–TS12, on a per-channel basis. Setting a bit in the SSIEx
register allows signaling data to be sourced from the signaling registers for that channel.
In transparent mode, bit 7 stuffing and/or robbed-bit signaling is prevented from overwriting the data in
the channels. If a DS0 is programmed to be clear, no robbed-bit signaling is inserted nor does the channel
have bit 7 stuffing performed. However, in the D4 framing mode, bit 2 is overwritten by a 0 when a
Yellow Alarm is transmitted. Also, the user has the option to globally override the SSIEx registers from
determining which channels are to have bit 7 stuffing performed. If the T1TCR1.3 and T1TCR2.0 bits are
set to 1, then all 24 T1 channels have bit 7 stuffing performed on them, regardless of how the SSIEx
registers are programmed. In this manner, the SSIEx registers are only affecting the channels that are to
have robbed-bit signaling inserted into them.
8.3
The DS2156 can transmit and detect the RAI-CI and AIS-CI codes in T1 mode. These codes are
compatible with and do not interfere with the standard RAI (Yellow) and AIS (Blue) alarms. These codes
are defined in ANSI T1.403.
The AIS-CI code (alarm indication signal-customer installation) is the same for both ESF and D4
operation. Setting the TAIS-CI bit in the T1CCR1 register and the TBL bit in the T1TCR1 register causes
the DS2156 to transmit the AIS-CI code. The RAIS-CI status bit in the SR4 register indicates the
reception of an AIS-CI signal.
The RAI-CI (remote alarm indication-customer installation) code for T1 ESF operation is a special form
of the ESF Yellow Alarm (an unscheduled message). Setting the RAIS-CI bit in the T1CCR1 register
causes the DS2156 to transmit the RAI-CI code. The RAI-CI code causes a standard Yellow Alarm to be
detected by the receiver. When the host processor detects a Yellow Alarm, it can then test the alarm for
the RAI-CI state by checking the BOC detector for the RAI-CI flag. That flag is a 011111 code in the 6-
bit BOC message.
The RAI-CI code for T1 D4 operation is a 10001011 flag in all 24 time slots. To transmit the RAI-CI
code the host sets all 24 channels to idle with a 10001011 idle code. Since this code meets the
requirements for a standard T1 D4 Yellow Alarm, the host can use the receive channel monitor function
to detect the 100001011 code whenever a standard Yellow Alarm is detected.
T1 Transmit Transparency
AIS-CI and RAI-CI Generation and Detection
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