Rainbow Electronics DS3170 - Manual (Page 75)

DS3170 DS3/E3 Single-Chip Transceiver
75 of 233
Table 9-18 lists the LAIS decodes for various line AIS enable modes.
Table 9-18. Line AIS Enable Modes
LAIS[1:0]
PORT.CR1
FRAME MODE DESCRIPTION AIS CODE
00
DS3
Automatic AIS when DLB is enabled
( PORT.CR4 .LBM = 1XX)
DS3AIS
00 E3 Automatic AIS when DLB is enabled UA1
01 Any Send UA1 UA1
10 DS3 Send AIS DS3AIS
10 E3 Send AIS UA1
11 Any Disable none
Table 9-19 lists the PAIS decodes for various payload AIS enable modes.
Table 9-19. Payload (Downstream) AIS Enable Modes
PAIS[2:0]
PORT.CR1
WHEN AIS IS SENT AIS CODE
000 Always UA1
001 When LLB (no DLB) active UA1
010 When PLB active UA1
011 When LLB(no DLB) or PLB active UA1
100 When LOS (no DLB) active UA1
101 When OOF active UA1
110 When OOF, LOS. LLB (no DLB), or
PLB active UA1
111 Never none
9.5.4 Loop Timing Mode
Loop timing mode is enabled by setting the PORT.CR3.LOOPT bit. This mode replaces the clock from the TCLKI
pin with the internal receive clock from either the RLCLK 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.
9.5.5 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.
9.5.6 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.
9.5.7 BERT
There is a Bit Error Rate Test (BERT) circuit 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