ds3171n Maxim Integrated Products, Inc., ds3171n Datasheet - Page 74

• Manufacturer Part Number: ds3171n
• Description: Ds3171, Ds3172, Ds3173, Ds3174 Single/dual/triple/quad Ds3/e3 Single-chip Transceivers
• Manufacturer: Maxim Integrated Products, Inc.

Table 10-19
Table 10-19. Payload (Downstream) AIS Enable Modes
10.5.4 Loop Timing Mode
Loop timing mode is enabled by setting the PORT.CR3.LOOPT bit. This mode replaces the clock from the TCLKIn
pin with the internal receive clock from either the RLCLKn pin if the RX LIU is disabled, or the recovered clock from
the RX LIU if it is enabled. The loop-timing mode can be activated in any framing or line interface mode.
10.5.5 HDLC Overhead Controller
The data signal to the receive HDLC controller will be forced to a one while still being clocked when the framer
(DS3, E3), to which the HDLC is connected, detects LOF or AIS. Forcing the data signal to all ones will cause an
HDLC packet abort if the data started to look like a packet instead of allowing a bad, and possibly very long, HDLC
packet.
10.5.6 Trail Trace
There is a single Trail Trace controller for use in line maintenance protocols. The E3-G.832 framer has access to
the trail trace controller.
10.5.7 BERT
There is a Bit Error Rate Test (BERT) circuit for each port for use in generating and detecting test signals in the
payload bits. The BERT can generate and detect PRBS patterns up to 2^32-1 bits as well as repeating patterns up
to 32 bits long. The generated BERT signal replaces the data on the TSERn pin in SCT modes when the BERT is
enabled by setting the PORT.CR1.BENA.
When the BERT is enabled The TDENn and RDENn pins will still be active but the data on the TSERn pin will be
discarded.
10.5.8 SCT port pins
The SCT port pins have multiple functions based on the framing mode the device is in as well as other pin mode
select bits.
10.5.8.1 Transmit SCT port pins
The transmit SCT pins are TSOFIn, TSERn, TSOFOn / TDENn, and TCLKOn / TGCLKn. They have different
functions based on the framing mode and other pin mode bits. Unused input pin functions should drive a logic zero
into the device circuits expecting a signal from that pin. The control bits that configure the pins’ modes are
PORT.CR2.FM[2:0], PORT.CR3.TPFPE, PORT.CR3.TSOFOS and PORT.CR3.TCLKS.
PORT.CR1
PAIS[2:0]
000
001
010
011
100
101
110
111
lists the PAIS decodes for various payload AIS enable modes.
When AIS is sent
Always
When LLB (no DLB) active
When PLB active
When LLB(no DLB) or PLB active
When LOS (no DLB) active
When OOF active
When OOF, LOS. LLB (no DLB), or
PLB active
Never
AIS Code
74
none
UA1
UA1
UA1
UA1
UA1
UA1
UA1