ST72521R9-Auto STMicroelectronics, ST72521R9-Auto Datasheet - Page 53

• Manufacturer Part Number: ST72521R9-Auto
• Description: 8-bit MCU for automotive
• Manufacturer: STMicroelectronics

Specifications of ST72521R9-Auto

• Hdflash Endurance: 100 cycles, data retention 20 years
• Clock Sources: crystal/ceramic resonator oscillators, internal RC oscillator and bypass for external clock
• 4 Power Saving Modes: Halt, Active Halt, Wait and Slow

ST72521xx-Auto
Table 15.
Figure 17. 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 18
Figure 18. 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.
RESTORE PC, X, A, CC
describes this decision process.
Interrupt software priority
RESET
FROM STACK
Interrupt software priority levels
PRIORITY SERVICED
HIGHEST HARDWARE
Same
Doc ID 17660 Rev 1
Y
INSTRUCTION
INTERRUPT
INSTRUCTION
FETCH NEXT
PENDING
EXECUTE
N
“IRET”
N
INTERRUPTS
SOFTWARE
PRIORITY
PENDING
Y
PRIORITY SERVICED
HIGHEST SOFTWARE
THE INTERRUPT
STAYS PENDING
Level
High
Low
Different
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
TRAP
I1:0
N
Interrupts
I0
0
1
0
1
Y
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