cx28250 Mindspeed Technologies, cx28250 Datasheet - Page 58

• Manufacturer Part Number: cx28250
• Description: Cx28250 Atm Physical Interface Phy Devices
• Manufacturer: Mindspeed Technologies

2.0 Functional Description
2.3 SONET/SDH Framer and Overhead Processor
InsLnAIS Pin (Insert Line AIS)
2-22
LFOut (Line Fail Output Pin)
2.3.3.5 K1 and K2
2.3.3.6 Line RDI
2.3.3.7 Line AIS
2.3.3.8 D4-12
The APS Channel bytes, K1 and K2, are allocated for Automatic Protection
Switching (APS) signaling between line level entities. These bytes are defined
only once in an STS-3c/STM-1 signal. The K1/K2 Transmit control registers
(0x10/0x11) allow transmission of any value in support of APS. The K2 byte, bits
6-8, Remote Defect Indicator (RDI), and Alarm Indication Signal (AIS), are used
to indicate STS line yellow, an alarm condition to the downstream line equipment.
values. An interrupt can be generated for any change in the received value. The
K1/K2 status bit is set when the receive K1/K2 values are the same for three
consecutive frames, but different from the previously latched values. When this
occurs, the new values are latched, and an interrupt is generated. A Protection
Switching Byte Failure (PSBF) alarm is declared if no three adjacent frames
contain the same K1 value in 12 consecutive frames. Bit 4 of the RXAPS register
(0x4A) indicates PSBF.
The Remote Defect Indication-Line (RDI-L) signal indicates to a Line
Terminating Equipment (LTE) that the remote equipment is detecting a defect
somewhere along the SONET line. A line RDI condition is declared when bits
6,7, and 8 of the received K2 octet contain 110 for five consecutive frames. A line
RDI condition is cleared when bits 6,7, and 8 of the received K2 octet contain any
other pattern for five consecutive frames. An interrupt is generated when entering
and exiting the RDI-L alarm state.
the TXLIN register. This sends the binary code 110 in bits 6, 7, and 8 of the K2
octet.
automatically generated upon reception of LOS, LOF, or AIS-L. If the
AutoLnRDI bit is asserted and none of the above alarm conditions are present the
value of the RDI-L field will be selected from the TXK2 register.
The Alarm Indication Signal-Line (AIS-L) is sent to alert the downstream LTE
that a defect has been detected on the incoming SONET section. Bits 6-8 of the
K2 octet are also used to convey this information. If the received pattern is 111
for five consecutive frames, an AIS-L condition is declared. An AIS-L condition
is cleared when five consecutive frames do not contain the 111 pattern. An
interrupt is generated when entering and exiting the AIS-L alarm state.
register. Line AIS sets all frame values except for the section overhead to 1’s
before scrambling. It is synchronized to frame boundaries.
When asserted high, this input forces the CX28250 to generate an AIS-L, which
has the same effect as setting InsLnAIS, bit 3 of the TXLIN register.
This output is controlled by the EnLFOut register, 0x6E. If any of the status bits
shown in
all enabled status bits are low.
See
The K2 receive status register (0x15) allows observation of incoming octet
Line RDI is inserted into the transmit frame by asserting the InsLnRDI bit in
When the AutoLnRDI bit in the TXLIN register is asserted line RDI is
Line AIS can be transmitted by setting the InsLnAIS bit in the TXLIN
Section
Mindspeed Technologies
Figure 2-14
2.3.2.4.
are asserted, the LFOut pin goes high and stays high until
™
ATM Physical Interface (PHY) Devices
28250-DSH-002-C
CX28250