CHAPTER 17 INTERRUPT/EXCEPTION PROCESSING FUNCTION
User’s Manual U16896EJ2V0UD
536
Figure 17-1. Acknowledging Non-Maskable Interrupt Request Signals (2/2)
(b) If a new non-maskable interrupt request signal is generated
during a non-maskable interrupt servicing
Non-maskable
interrupt currently
being serviced
Non-maskable interrupt request newly generated during non-maskable interrupt servicing
NMI
INTWDT1
INTWDT2
NMI
· Generation of NMI request during NMI processing
· Generation of INTWDT1 request during NMI processing
(NP = 1 state prior to INTWDT1 request is maintained)
· Generation of INTWDT1 request during NMI processing
(Set NP = 0 before INTWDT1 request)
· Generation of INTWDT1 request during NMI processing
(Set NP = 0 after INTWDT1 request)
· Generation of INTWDT2 request during NMI processing
Main routine
NMI request
→
NMI processing
(Held pending)
NMI processing
NMI request
→
(Hold pending)
Main routine
System reset
NMI request
→
NMI request
→
NMI processing
INTWDT1
processing
→
(Hold pending)
Main routine
System reset
NMI request
→
NMI request
→
NMI
processing
INTWDT1
processing
INTWDT1
request
→
NP = 0
→
NP = 0
→
Main routine
System reset
INTWDT2
→
request
NMI processing
INTWDT2
processing
· Generation of INTWDT2 request during INTWDT1 processing
Main routine
System reset
INTWDT1
→
request
INTWDT1
processing
INTWDT2
processing
INTWDT2 request
→
Main routine
System reset
NMI
processing
INTWDT1
processing
INTWDT1
→
(Hold pending)
request
INTWDT1
→
(Invalid)
request
· Generation of INTWDT1 request during INTWDT1 processing
Main routine
System reset
INTWDT1
processing
· Generation of NMI request during INTWDT1 processing
INTWDT1
INTWDT2
Main routine
System reset
INTWDT1
request
→
INTWDT1
request
→
INTWDT1
processing
NMI request
→
(Invalid)
NMI request
→
(Invalid)
· Generation of INTWDT2 request during INTWDT2 processing
· Generation of INTWDT1 request during INTWDT2 processing
Main routine
System reset
INTWDT2
processing
Main routine
System reset
INTWDT2
processing
· Generation of NMI request during INTWDT2 processing
Main routine
System reset
INTWDT2 request
→
INTWDT2 request
→
INTWDT2
processing
INTWDT1
→
(Invalid)
request
INTWDT2
→
(Invalid)
request
INTWDT1
request
INTWDT2
→
request