60
7598H–AVR–07/09
ATtiny25/45/85
11.3 General Interrupt Flag Register – GIFR
• Bits 7, 4..0 – Res: Reserved Bits
These bits are reserved bits in the ATtiny25/45/85 and will always read as zero.
• Bit 6 – 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 GIMSK are set (one), the MCU will jump to the cor-
responding 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 always cleared
when INT0 is configured as a level interrupt.
• Bit 5 – PCIF: Pin Change Interrupt Flag
When a logic change on any PCINT5..0 pin triggers an interrupt request, PCIF becomes set
(one). If the I-bit in SREG and the PCIE bit in GIMSK are set (one), the MCU will jump to the cor-
responding 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.
11.4 Pin Change Mask Register – PCMSK
• Bits 7, 6 – Res: Reserved Bits
These bits are reserved bits in the ATtiny25/45/85 and will always read as zero.
• Bits 5..0 – PCINT5..0: Pin Change Enable Mask 5..0
Each PCINT5..0 bit selects whether pin change interrupt is enabled on the corresponding I/O
pin. If PCINT5..0 is set and the PCIE bit in GIMSK is set, pin change interrupt is enabled on the
corresponding I/O pin. If PCINT5..0 is cleared, pin change interrupt on the corresponding I/O pin
is disabled.
Bit 76543210
–INTF0PCIF–––––GIFR
Read/Write R R/W R/W R R R R R
Initial Value 0 0 0 0 0 0 0 0
Bit 76543210
– – PCINT5 PCINT4 PCINT3 PCINT2 PCINT1 PCINT0 PCMSK
Read/Write R R R/W R/W R/W R/W R/W R/W
Initial Value 0 0 1 1 1 1 1 1
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