NEC PD754144 User Manual
Page 207
CHAPTER 7 INTERRUPT AND TEST FUNCTIONS
207
User’s Manual U10676EJ3V0UM
(3) Nesting of interrupts with higher priority (INTBT has higher priority and INTT0 and INTT2 have lower
priority)
<1>
Reset
INTT0
<2>
SEL
EI
EI
EI
MOV
MOV
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RB2
IEBT
IET0
IET2
A, #9
IPS, A
Status 0
Status 0
Status 1
RETI
; RBE = 1, MBE = 0
; RBE = 0
Status 1
Status 2
; RBE = 1
INTBT
<3>
SEL RB1
<4>
SEL RB2
RETI
<5>
<1> INTBT is specified as having a higher priority by setting of IPS, and interrupts are enabled at the same
time.
<2> INTT0 servicing program is started when INTT0 with a lower priority occurs. Status 1 is set and the other
interrupts with a lower priority are disabled. RBE = 0 to select register bank 0.
<3> INTBT with a higher priority occurs. The interrupts are nested. The status is changed to 0 and all
interrupts are disabled.
<4> RBE = 1 and RBS = 1 to select register bank 1 (only the registers used may be saved by the PUSH
instruction).
<5> RBS is returned to 2, and execution returns to the main routine. The status is returned to 1.