DS3170 Maxim Integrated Products, DS3170 Datasheet - Page 91

• Manufacturer Part Number: DS3170
• Description: Network Controller & Processor ICs DS3-E3 Single-Chip T ransceiver T3-E3 Fra
• Manufacturer: Maxim Integrated Products

DS3170 DS3/E3 Single-Chip Transceiver
A Change Of Frame Alignment (COFA) is declared when the G.751 E3 framer updates the data path frame
counters with a frame alignment that is different from the current data path frame alignment.
A Loss Of Signal (LOS) condition is declared when the HDB3 encoder is active, and it declares an LOS condition.
An LOS condition is terminated when the HDB3 encoder is inactive, or it terminates an LOS condition.
An Alarm Indication Signal (AIS) condition is declared when 4 or less zeros are detected in each of two consecutive
frame periods. An AIS condition is terminated when 5 or more zeros are detected in each of two consecutive frame
periods.
A Receive Unframed All 1’s (RUA1) condition is declared if in each of 4 consecutive 2047 bit windows, five or less
zeros are detected and an OOF condition is continuously present. A RUA1 condition is terminated if in each of 4
consecutive 2047 bit windows, six or more zeros are detected or an OOF condition is continuously absent.
A Remote Alarm Indication (RAI) condition is declared when four consecutive frames are received with the A bit
(first bit after the FAS) set to one. An RAI condition is terminated when four consecutive frames are received with
the A bit set to zero.
Only framing errors are accumulated. Framing errors are determined by comparing the FAS to its expected value.
The type of framing errors accumulated is programmable (OOFs, bit, or word). An OOF error increments the count
whenever an OOF condition is first detected. A bit error increments the count once for each bit in the FAS that does
not match its expected value (up to 10 per frame. A word error increments the count once for each FAS that does
not match its expected value (up to 1 per frame).
The receive alarm indication (RAI) signal is high when one or more of the indicated alarm conditions is present, and
low when all of the indicated alarm conditions are absent. Setting the receive alarm indication on LOS, OOF, LOF,
or AIS is individually programmable (on or off).
10.6.7.6.3 Receive G.751 E3 Overhead Extraction
Overhead extraction extracts all of the E3 overhead bits from the G.751 E3 frame. The FAS, A bit, and N bit are
output on the receive overhead interface (ROH, ROHSOF, and ROHCLK). In addition, the A bit is integrated and
stored in a register along with a change indication, and can be output over the receive FEAC controller. The N bit is
integrated and stored in a register along with a change indication, is sent to the receive HDLC overhead controller,
and can also be sent to the receive FEAC controller. The bit sent to the receive FEAC controller is programmable
(A or N).
10.6.7.6.4 Receive G.751 Downstream AIS Generation
Downstream G.751 E3 AIS can be automatically generated on an OOF, LOS, or AIS condition or manually
inserted. If automatic downstream AIS is enabled, downstream AIS is inserted when an LOS, OOF, or AIS
condition is declared. Automatic downstream AIS is programmable (on or off). If manual downstream AIS insertion
is enabled, downstream AIS is inserted. Manual downstream AIS insertion is programmable (on or off).
Downstream AIS is removed when all OOF, LOS, and AIS conditions are terminated and manual downstream AIS
insertion is disabled. RPDT will be forced to all ones during downstream AIS.
10.6.8 G.832 E3 Framer/Formatter
10.6.8.1 Transmit G.832 E3 Frame Processor
The G.832 E3 frame format is shown in
Figure
10-17.
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