58
8008H–AVR–04/11
ATtiny48/88
9.3.5
PCIFR – Pin Change Interrupt Flag Register
Bits 7:4 – Res: Reserved Bits
These bits are reserved and will always read zero.
Bit 3 – PCIF3: Pin Change Interrupt Flag 3
When a logic change on any PCINT[27:24] pin triggers an interrupt request, PCIF3 becomes set
(one). If the I-bit in SREG and the PCIE3 bit in PCICR are set (one), the MCU will jump to the
corresponding Interrupt Vector. The flag is cleared when the interrupt routine is executed. Alter-
natively, the flag can be cleared by writing a logical one to it.
Bit 2 – PCIF2: Pin Change Interrupt Flag 2
When a logic change on any PCINT[23:16] pin triggers an interrupt request, PCIF2 becomes set
(one). If the I-bit in SREG and the PCIE2 bit in PCICR are set (one), the MCU will jump to the
corresponding Interrupt Vector. The flag is cleared when the interrupt routine is executed. Alter-
natively, the flag can be cleared by writing a logical one to it.
Bit 1 – PCIF1: Pin Change Interrupt Flag 1
When a logic change on any PCINT[15:8] pin triggers an interrupt request, PCIF1 becomes set
(one). If the I-bit in SREG and the PCIE1 bit in PCICR are set (one), the MCU will jump to the
corresponding Interrupt Vector. The flag is cleared when the interrupt routine is executed. Alter-
natively, the flag can be cleared by writing a logical one to it.
Bit 0 – PCIF0: Pin Change Interrupt Flag 0
When a logic change on any PCINT[7:0] pin triggers an interrupt request, PCIF0 becomes set
(one). If the I-bit in SREG and the PCIE0 bit in PCICR are set (one), the MCU will jump to the
corresponding Interrupt Vector. The flag is cleared when the interrupt routine is executed. Alter-
natively, the flag can be cleared by writing a logical one to it.
9.3.6
PCMSK3 – Pin Change Mask Register 3
Bits 7:4 – Res: Reserved Bits
These bits are reserved and will always read zero.
Bits 3:0 – PCINT[27:24]: Pin Change Enable Mask 27:24
Each PCINT[27:24] bit selects whether pin change interrupt is enabled on the corresponding I/O
pin. If PCINT[27:24] is set and the PCIE3 bit in PCICR is set, pin change interrupt is enabled on
the corresponding I/O pin. If PCINT[27:24] is cleared, pin change interrupt on the corresponding
I/O pin is disabled.
Bit
76543
210
––––
PCIF3
PCIF2
PCIF1
PCIF0
PCIFR
Read/Write
R
R/W
Initial Value
00000
000
Bit
7
65
43
2
1
0
––
PCINT27
PCINT26
PCINT25
PCINT24
PCMSK3
Read/Write
R
R/W
Initial Value
0