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49
4958B–AUTO–11/10
Atmel ATA6285/ATA6286 [Preliminary]
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 programmed, interrupts are disabled while
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.
3.11
External Interrupts
The Ext e rnal I n terrupts ar e t r igger ed by t he I N T0 pin or INT1 pin or any of the
PCINT23..16,10..0 pins. Observe that, if enabled, the interrupts will trigger even if the INT0 or
INT1 or PCINT23..16,10..0 pins are configured as outputs. This feature provides a way of gener-
ating a software interrupt. The pin change interrupt PCI2 will trigger if any enabled PCINT23..16
pin toggles. The pin change interrupt PCI1 will trigger if any enabled PCINT10..8 pin toggles. Pin
change interrupt PCI0 will trigger if any enabled PCINT7..0 pin toggles. The PCMSK2, PCMSK1
and PCMSK0 Registers control which pins contribute to the pin change interrupts. Pin change
interrupts on PCINT23..16,10..0 are detected asynchronously. This implies that these interrupts
can be used for waking the part also from sleep modes other than Idle mode.
The INT0 or INT1 interrupts can be triggered by a falling or rising edge or a low level. This is set
up as indicated in the specification for the External Interrupt Control Register A - EICRA. When
the INT0 or INT1 interrupt is enabled and is configured as level triggered, the interrupt will trigger
as long as the pin is held low. Note that recognition of falling or rising edge interrupts on INT0 or
implies that this interrupt can be used for waking the part also from sleep modes other than Idle
mode. The I/O clock is halted in all sleep modes except Idle mode.
Note that if a level triggered interrupt is used for wake-up from Power-down, the required level
must be held long enough for the MCU to complete the wake-up to trigger the level interrupt. If
the level disappears before the end of the Start-up Time, the MCU will still wake up, but no inter-
rupt will be generated. The start-up time is defined by the SUT Fuses and CMM2..0 as described