ST72F324BK6TAS STMicroelectronics, ST72F324BK6TAS Datasheet - Page 42

• Manufacturer Part Number: ST72F324BK6TAS
• Description: 8-BIT MCU
• Manufacturer: STMicroelectronics

Interrupts
7.2.1
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Table 14.
Figure 16. 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 17
Figure 17. Priority decision process flowchart
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.
describes this decision process.
Interrupt software priority
RESTORE PC, X, A, CC
Interrupt software priority levels
Reset
from stack
HIGHEST HARDWARE
PRIORITY SERVICED
Doc ID13466 Rev 4
Same
Y
Pending
I
instruction
Fetch next
nterrupt
I
nstruction
Execute
N
“IRET”
N
INTERRUPTS
SOFTWARE
PRIORITY
PENDING
HIGHEST SOFTWARE
PRIORITY SERVICED
Y
stays pending
The interrupt
Interrupt has the same or a
Level
Different
High
Low
lower software priority
load I1:0 from interrupt SW reg.
than current one
load PC from interrupt vector
Stack PC, X, A, CC
I1
1
0
0
1
TRAP
I1:0
ST72324B-Auto
N
Y
I0
0
1
0
1