st72324bk STMicroelectronics, st72324bk Datasheet - Page 30

• Manufacturer Part Number: st72324bk
• Description: 3 V/5 V Range 8-bit Mcu With 4/8 Kbyte Rom, 10-bit Adc, Four Timers And Spi
• Manufacturer: STMicroelectronics

Interrupts
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Table 5.
Figure 13. Interrupt processing flowchart
Servicing pending interrupts
As several interrupts can be pending at the same time, the interrupt to be taken into account
is determined by the following two-step process:
●
●
Figure 14
Interrupt software priority
Level 0 (main)
Level 1
Level 2
Level 3 (= interrupt disable)
the highest software priority interrupt is serviced,
if several interrupts have the same software priority then the interrupt with the highest
hardware priority is serviced first.
RESTORE PC, X, A, CC
describes this decision process.
RESET
FROM STACK
Interrupt software priority levels
Y
INSTRUCTION
INTERRUPT
INSTRUCTION
FETCH NEXT
PENDING
EXECUTE
N
“IRET”
N
Y
STAYS PENDING
THE INTERRUPT
Level
High
Low
Interrupt has the same or a
LOAD I1:0 FROM INTERRUPT SW REG.
LOAD PC FROM INTERRUPT VECTOR
lower software priority
than current one
STACK PC, X, A, CC
I1
1
0
0
1
ST72323 ST72323L
TRAP
I1:0
N
I0
0
1
0
1
Y