Datasheet
2018 Microchip Technology Inc. Data Sheet Complete DS40002060A-page 48
ATtiny4/5/9/10
period will generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt. If low level interrupt is
selected, the low level must be held until the completion of the currently executing instruction to generate an interrupt.
10.3.2 EIMSK – External Interrupt Mask Register
• Bits 7:1 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 0 – INT0: External Interrupt Request 0 Enable
When the INT0 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), the external pin interrupt is enabled.
The Interrupt Sense Control bits (ISC01 and ISC00) in the External Interrupt Control Register A (EICRA) define whether the
external interrupt is activated on rising and/or falling edge of the INT0 pin or level sensed. Activity on the pin will cause an
interrupt request even if INT0 is configured as an output. The corresponding interrupt of External Interrupt Request 0 is
executed from the INT0 Interrupt Vector.
10.3.3 EIFR – External Interrupt Flag Register
• Bits 7:1 – Res: Reserved Bits
These bits are reserved and will always read zero.
• Bit 0 – INTF0: External Interrupt Flag 0
When an edge or logic change on the INT0 pin triggers an interrupt request, INTF0 becomes set (one). If the I-bit in SREG
and the INT0 bit in EIMSK are set (one), the MCU will jump to the corresponding Interrupt Vector.
The flag is cleared when the interrupt routine is executed. Alternatively, the flag can be cleared by writing a logical one to it.
This flag is constantly zero when INT0 is configured as a level interrupt.
Table 10-2. Interrupt 0 Sense Control
ISC01 ISC00 Description
0 0 The low level of INT0 generates an interrupt request.
0 1 Any logical change on INT0 generates an interrupt request.
1 0 The falling edge of INT0 generates an interrupt request.
1 1 The rising edge of INT0 generates an interrupt request.
Bit 76543210
0x13
– – – – – – –INTOEIMSK
Read/Write RRRRRRRR/W
Initial Value 0 0 0 0 0 0 0 0
Bit 76543210
0x14
– – – – – – –INTF0EIFR
Read/Write RRRRRRRR/W
Initial Value 0 0 0 0 0 0 0 0