CHAPTER 3 FUNCTIONAL OUTLINE
PRELIMINARY
NEC confidential and Proprietary
110
3.8 Loopback
Function
The two types of loopback modes are supported. These modes can be selected by using the MDPGEN register.
(1) Equipment Loopback
The data input to the transmission side of the ATM/POS interface is looped back at the
µ
PD98413 internal, and is
output from the reception side of the ATM/POS interface. When loopback is set, the loop data is not output to
the transmission line side. Instead, a frame that is mapped Line AIS frame is transmitted. If the ELPOM bit of
the MDPGEN register is set, the loop data can also be sent to the transmission line.
Figure 3-34. Equipment Loopback
Tx FIFO
Rx FIFO
Tx ATM
Processor
Tx POS
Processor
Rx ATM
Processor
Rx POS
Processor
A
T
M
/
P
O
S
I
n
t
e
r
f
a
c
e
Rx POH
Processor
Rx SOH
Processor
Tx POH
Processor
Tx SOH
Processor
(2) Line Loopback
In this mode, the data input from the reception side of the line interface is returned at the
µ
PD98413 internal and
output from the transmission side of the line interface.
Figure 3-35. Line Loopback
Tx PLL
SDT0
Lock state
RDIT0/
RDIC0
CDR
SD
CNT
DEMUX 0
1:8
MUX 0
8:1
TDOT0/
TDOC0
Summary of Contents for NEASCOT-P65
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