Detection Of Alarm And Failure - NEC UPD98413 User Manual

3.4.2 Detection of Alarm and Failure

Table 3-14 lists the failures and alarms monitored by the µ PD98413. If any of these events has been detected,
the following actions are taken.
<1> The corresponding bit of the interrupt cause register is set.
The CPU identifies the event that has occurred by reading the register.
<2> An interrupt signal is asserted active to report the host.
Whether an interrupt signal corresponding to each event is asserted active (mask, unmask) can be selected.
<3> The corresponding pin is asserted active.
If an event occurs, the corresponding alarm output pin (RALM pins) goes high to report the external
peripheral device.
LOS (Loss Of Signal)
Receive signal lost status
Detection: See section 3.1.2 (Table 3-2)
Termination: See section 3.1.2 (Table 3-2)
OOF (Out Of Frame)
Frame non-synchronization
Detection: If a frame synchronization pattern cannot be detected
Termination: If a frame synchronization pattern is detected
α δ
* = 3, 4, 5, or 6, = 2, 3, or 4. These values can be selected by using the OOFD[1:0] and OOFT[1:0] bits of the MDSOHR
register. In the default mode,
LOF (Loss Of Frame)
Frame lost status
Detection: If OOF status lasts for T ms
Termination: If not OOF status lasts for T ms
* T = 3 ms or 0 ms. This can be selected by using the LOFDT bit of the MDSOHR register.
In the default mode, T = 3 ms. When T = 0 ms, the detection/clearing condition is the same as that of OOF.
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CHAPTER 3 FUNCTIONAL OUTLINE
Table 3-14. Alarms and Failures (1/4)
δ
times in a row.
α δ
= 4 and = 2.
PRELIMINARY
α
times in a row at the positions of the A1 and A2 bytes.
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