Rainbow Electronics ATmega64M1 - Manual (Page 62)

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8209A–AVR–08/09
ATmega16M1/32M1/64M1
13.2.3 EIFR – External Interrupt Flag Register
• Bit 7:4 – Res: Reserved
These bits are reserved and will always read as zero.
• Bit 3:0 – INTF[3:0]: External Interrupt Flag 3:0
When an edge or logic change on the INT3:0 pin triggers an interrupt request, INTF3:0 becomes
set (one). If the I-bit in SREG and the corresponding interrupt enable bit INT3:0 in EIMSK, are
set (one), the MCU will jump to the 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. These flags are
always cleared when INT3:0 are configured as a level interrupt.
13.2.4 PCICR – Pin Change Interrupt Control Register
• Bit 7:4 - Res: Reserved
These bits are reserved and will always read as zero.
• Bit 3 - PCIE3: Pin Change Interrupt Enable 3
When the PCIE3 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), pin
change interrupt 3 is enabled. Any change on any enabled PCINT26:24 pin will cause an inter-
rupt. The corresponding interrupt of Pin Change Interrupt Request is executed from the PCI3
Interrupt Vector. PCINT26:24 pins are enabled individually by the PCMSK3 Register.
• Bit 2 - PCIE2: Pin Change Interrupt Enable 2
When the PCIE2 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), pin
change interrupt 2 is enabled. Any change on any enabled PCINT23:16 pin will cause an inter-
rupt. The corresponding interrupt of Pin Change Interrupt Request is executed from the PCI2
Interrupt Vector. PCINT23:16 pins are enabled individually by the PCMSK2 Register.
• Bit 1 - PCIE1: Pin Change Interrupt Enable 1
When the PCIE1 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), pin
change interrupt 1 is enabled. Any change on any enabled PCINT14:8 pin will cause an inter-
rupt. The corresponding interrupt of Pin Change Interrupt Request is executed from the PCI1
Interrupt Vector. PCINT14:8 pins are enabled individually by the PCMSK1 Register.
• Bit 0 - PCIE0: Pin Change Interrupt Enable 0
When the PCIE0 bit is set (one) and the I-bit in the Status Register (SREG) is set (one), pin
change interrupt 0 is enabled. Any change on any enabled PCINT7:0 pin will cause an interrupt.
The corresponding interrupt of Pin Change Interrupt Request is executed from the PCI0 Inter-
rupt Vector. PCINT7:0 pins are enabled individually by the PCMSK0 Register.
Bit 7 6 5 4 3 2 1 0
– – – – INTF3 INTF2 INTF1 INTF0 EIFR
Read/Write R R R R R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Bit 7 6 5 4 3 2 1 0
– – – – PCIE3 PCIE2 PCIE1 PCIE0 PCICR
Read/Write R R R R R R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0