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(4) Bit error rate monitoring
This is a function for monitoring the bit error rates for B2 errors. It reports the signal failure (SF) and signal
degrade (SD) when the error rate, which is set in advance, is reached. An interrupt (DSLER, TSLER, SSLER
register) or the relevant alarm output pin is used to notify the CPU and peripheral devices of the degradation.
The user can be select the source of the bit error rate monitoring which are B1, B2 and B3 errors. It is set to the
MDBER register and the default is B2 error.
Table 3-17. Conditions to Detect Error Rate Degradation Alarms
SF (Signal Failure)
Signal failure alarm.
Detection: A specific number of frames are defined as one frame to be monitored, called the ND frame. This alarm is
detected when an ND frame (one) in which LD or more bit errors are detected is received MD consecutive times.
Termination: A specific number of frames are defined as one frame to be monitored, called the NT frame. This alarm is
cleared when an NT frame (one) in which less than LT bit errors are detected is received MT consecutive times.
SD (Signal Degrade)
Signal degrade alarm.
Detection: A specific number of frames are defined as one frame to be monitored, called the ND frame. This alarm is
detected when an ND frame (one) in which LD or more bit errors are detected is received MD consecutive times.
Termination: A specific number of frames are defined as one frame to be monitored, called the NT frame. This alarm is
cleared when an NT frame (one) in which less than LT bit errors are detected is received MT consecutive times.
The bit error monitor function starts monitoring in accordance with the default value after power application. To
change the parameters, disable the monitor function by using the SFM [1:0] and SDM [1:0] bits of the MDBER
register.
Figure 3-29. Registers and Default Values of Bit Error Rate Parameters
SFND and SDND registers
23
ND [23:0]
SFNT and SDNT registers
23
NT [23:0]
ND
NT
LD
LT
MD
MT
96
CHAPTER 3 FUNCTIONAL OUTLINE
SFLMD and SDLMD register
0
19
LD [11:0]
SFLMT and SDLMT register
0
19
LT [11:0]
Default Values of the Parameters
Parameter
Number of frames (24 bits)
Number of errors detected (12 bits)
Number of consecutive frames (8 bits)
PRELIMINARY
8 7
0
MD [8:0]
8 7
0
MT [8:0]
SF
SD
000 H
000 H
000 H
000 H
00 H
00 H
NEC confidential and Proprietary
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