ST72F324K2TCRS View Datasheet(PDF) - STMicroelectronics

Part Name

Description

MFG CO.

ST72F324K2TCRS

8-bit MCU for automotive, 3.8 to 5.5V operating range with 8 to 32 Kbyte Flash, 10-bit ADC, 4 timers, SPI, SCI

STMicroelectronics 

ST72324xx-Auto

Interrupts

Table 14. Interrupt software priority levels

Interrupt software priority

Level

I1

I0

Level 0 (main)

Level 1

Level 2

Level 3 (= interrupt disable)

Low

1

0

0

1

0

0

High

1

1

Figure 16. Interrupt processing flowchart

Reset

lete Product(s) Restore PC, X, A, CC

bso from stack

Pending

Y

Interrupt

N

Fetch next

Instruction

Y

“IRET”

N

Execute

instruction

Y

TRAP

Interrupt has the same or a

lower software priority

than current one

N

I1:0

The interrupt

stays pending

Stack PC, X, A, CC

Load I1:0 from interrupt SW reg.

Load PC from interrupt vector

Obsolete Product(s) - O 7.2.1

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:

1. The highest software priority interrupt is serviced.

2. If several interrupts have the same software priority, then the interrupt with the highest

hardware priority is serviced first.

Figure 17 describes this decision process.

Figure 17. Priority decision process flowchart

PENDING

INTERRUPTS

Same

SOFTWARE

PRIORITY

Different

HIGHEST SOFTWARE

PRIORITY SERVICED

HIGHEST HARDWARE

PRIORITY SERVICED

Doc ID 13841 Rev 1

43/193

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