ATmega328P datasheet(69/448 Pages) ATMEL

69 / 448 page

8161D–AVR–10/09

ATmega48PA/88PA/168PA/328P

IVSEL. If IVSEL is not written, interrupts remain disabled for four cycles. The I-bit in the Status

Note:

If Interrupt Vectors are placed in the Boot Loader section and Boot Lock bit BLB02 is programmed,

interrupts are disabled while executing from the Application section. If Interrupt Vectors are placed

in the Application section and Boot Lock bit BLB12 is programed, interrupts are disabled while

executing from the Boot Loader section. Refer to the section ”Boot Loader Support – Read-While-

Write Self-Programming, ATmega88PA, ATmega168PA and ATmega328P” on page 277 for

details on Boot Lock bits.

• Bit 0 – IVCE: Interrupt Vector Change Enable

The IVCE bit must be written to logic one to enable change of the IVSEL bit. IVCE is cleared by

hardware four cycles after it is written or when IVSEL is written. Setting the IVCE bit will disable

interrupts, as explained in the IVSEL description above. See Code Example below.

Assembly Code Example

Move_interrupts:

; Enable change of Interrupt Vectors

ldi

r16, (1<<IVCE)

out

MCUCR, r16

; Move interrupts to Boot Flash section

ldi

r16, (1<<IVSEL)

out

MCUCR, r16

ret

C Code Example

void

Move_interrupts(void)

{

/* Enable change of Interrupt Vectors */

MCUCR = (1<<IVCE);

/* Move interrupts to Boot Flash section */

MCUCR = (1<<IVSEL);

}

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