Datasheet

C Code Example
(1)
__enable_interrupt(); /* set Global Interrupt Enable */
__sleep(); /* enter sleep, waiting for interrupt */
/* note: will enter sleep before any pending interrupt(s) */
1. Refer to About Code Examples.
Related Links
Memory Programming on page 362
Boot Loader Support – Read-While-Write Self-Programming on page 345
About Code Examples on page 18
8.8.1. Interrupt Response Time
The interrupt execution response for all the enabled AVR interrupts is four clock cycles minimum. After
four clock cycles the program vector address for the actual interrupt handling routine is executed. During
this four clock cycle period, the Program Counter is pushed onto the Stack. The vector is normally a jump
to the interrupt routine, and this jump takes three clock cycles. If an interrupt occurs during execution of a
multi-cycle instruction, this instruction is completed before the interrupt is served. If an interrupt occurs
when the MCU is in sleep mode, the interrupt execution response time is increased by four clock cycles.
This increase comes in addition to the start-up time from the selected sleep mode. A return from an
interrupt handling routine takes four clock cycles. During these four clock cycles, the Program Counter
(two bytes) is popped back from the Stack, the Stack Pointer is incremented by two, and the I-bit in SREG
is set.
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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