
54
8008H–AVR–04/11
ATtiny48/88
means 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
INT0 or INT1 interrupts are enabled and are configured as level triggered, the interrupts will trig-
ger as long as the corresponding pin is held low. Note that recognition of falling or rising edge
interrupts on INT0 or INT1 requires the presence of an I/O clock, described in
“I/O Clock –9.2.1
Pin Change Interrupt Timing
An example of timing of a pin change interrupt is shown in
Figure 9-1.
Figure 9-1.
Timing of pin change interrupts
9.2.2
Low Level Interrupt
Low level interrupts on INT0 and INT1 are detected asynchronously. This means that the inter-
rupt sources can be used for waking the part also from sleep modes other than Idle (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-
clk
PCINT(0)
pin_lat
pin_sync
pcint_in_(0)
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