
59
2543L–AVR–08/10
ATtiny2313
External
Interrupts
The External Interrupts are triggered by the INT0 pin, INT1 pin or any of the PCINT7..0 pins.
Observe that, if enabled, the interrupts will trigger even if the INT0, INT1 or PCINT7..0 pins are
configured as outputs. This feature provides a way of generating a software interrupt. The pin
change interrupt PCIF will trigger if any enabled PCINT7..0 pin toggles. The PCMSK Register
control which pins contribute to the pin change interrupts. Pin change interrupts on PCINT7..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 and INT1 interrupts can be triggered by a falling or rising edge or a low level. This is
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
implies that this interrupt can be used for waking the part 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 and CKSEL Fuses as described
Pin Change
Interrupt Timing
An example of timing of a pin change interrupt is shown in
Figure 26.
Figure 26.
MCU Control Register
– MCUCR
The External Interrupt Control Register contains control bits for interrupt sense control.
clk
PCINT(n)
pin_lat
pin_sync
pcint_in_(n)
pcint_syn
pcint_setflag
PCIF
PCINT(0)
pin_sync
pcint_syn
pin_lat
D
Q
LE
pcint_setflag
PCIF
clk
PCINT(0) in PCMSK(x)
pcint_in_(0)
0
x
Bit
765
4321
0
PUD
SM1
SE
SM0
ISC11
ISC10
ISC01
ISC00
MCUCR