PIC16F15213 datasheet(89/439 Pages) MICROCHIP

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The following events happen when an interrupt event occurs while the GIE bit is set:

• Current prefetched instruction is flushed

• GIE bit is cleared

• Current Program Counter (PC) is pushed onto the stack

• Critical registers are automatically saved to the shadow registers (see Automatic Context Saving)

• PC is loaded with the interrupt vector 0004h

The firmware within the Interrupt Service Routine (ISR) may determine the source of the interrupt by polling the

interrupt flag bits. The interrupt flag bits must be cleared before exiting the ISR to avoid repeated interrupts. Because

the GIE bit is cleared, any interrupt that occurs while executing the ISR will be recorded through its interrupt flag, but

will not cause the processor to redirect to the interrupt vector.

The RETFIE instruction exits the ISR by popping the previous address from the stack, restoring the saved context

from the shadow registers and setting the GIE bit.

For additional information on a specific interrupts operation, refer to its peripheral section.

Important:

Individual interrupt flag bits are set, regardless of the state of any other enable bits.

All interrupts will be ignored while the GIE bit is cleared. Any interrupt occurring while the GIE bit is

clear will be serviced when the GIE bit is set again.

12.5

Interrupt Latency

Interrupt latency is defined as the time from when the interrupt event occurs to the time code execution at the

interrupt vector begins. The interrupt is sampled during Q1 of the instruction cycle. The actual interrupt latency then

depends on the instruction that is executing at the time the interrupt is detected. See the following figures for more

details.

Figure 12-2. Interrupt Latency

Rev. 10-000269E

8/31/2016

Q1 Q2

Q3 Q4

CLKIN

CLKOUT

INT

PC - 1

Fetch

Execute

PC - 2

PC - 1

PC + 1

NOP

PC = 0x0004

PC = 0x0005

PC = 0x0006

1 Cycle Instruction at PC

Latency

Valid Interrupt

window(1)

Indeterminate

Latency(2)

PIC16F15213/14/23/24/43/44

Interrupts

and its subsidiaries

Data Sheet

DS40002195E-page 89

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