Rainbow Electronics ATtiny43U - Manual (Page 58)

58
8048B–AVR–03/09
ATtiny43U
0x0008 rjmp TIM0_COMPA ; Timer0 Compare A Handler
0x0009 rjmp TIM0_COMPB ; Timer0 Compare B Handler
0x000A rjmp TIM0_OVF ; Timer0 Overflow Handler
0x000B rjmp ANA_COMP ; Analog Comparator Handler
0x000C rjmp ADC ; ADC Conversion Handler
0x000D rjmp EE_RDY ; EEPROM Ready Handler
0x000E rjmp USI_STR ; USI Start Handler
0x000F rjmp USI_OVF ; USI Overflow Handler
;
0x0010 RESET: ldi r16, low(RAMEND); Main program start
0x0011 out SPL,r16 ; Set Stack Pointer to top of RAM
0x0012 sei ; Enable interrupts
0x0013 <instr> xxx
... ... ... ...
10.2 External Interrupts
The External Interrupts are triggered by the INT0 pin or any of the PCINT pins. Observe that, if
enabled, the interrupts will trigger even if INT0 or the PCINT pins are configured as outputs. This
feature provides a way of generating a software interrupt, as follows.
• Pin Change Interrupt PCI0 triggers if a pin in PCINT7:0 is toggled while enabled
• Pin Change Interrupt PCI1 triggers if a pin in PCINT15:8 is toggled while enabled
The PCMSK0 and PCMSK1 Registers control which pins contribute to the pin change interrupts.
Pin change interrupts on PCINT15..0 are detected asynchronously. This means that these inter-
rupts can be used for waking the part also from sleep modes other than Idle mode.
The INT0 interrupt can be triggered by a falling or rising edge, or a low level. This is configured
as described in
“MCUCR – MCU Control Register” on page 59 . When the INT0 interrupt is
enabled and is configured as level triggered, the interrupt will trigger as long as the pin is held
low. Low level and edge interrupts on INT0 are detected asynchronously. This implies that these
interrupts 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
interrupt will be generated and execution will continue from the instruction following the SLEEP
command. The start-up time is defined by the SUT and CKSEL fuses, as described in
“System
Clock and Clock Options” on page 23 .
10.2.1 Pin Change Interrupt Timing
An example of timing of a pin change interrupt is shown in Figure 10-1 below.