AT90USB64/128
INT7
R/W
0
INT6
R/W
0
INT5
R/W
0
INT4
R/W
0
INT3
R/W
0
INT2
R/W
0
INT1
R/W
0
IINT0
R/W
0
EIMSK
Read/Write
Initial Value
• Bits 7..0 – INT7 – INT0: External Interrupt Request 7 - 0 Enable
When an INT7 – INT0 bit is written to one and the I-bit in the Status Register (SREG) is set
(one), the corresponding external pin interrupt is enabled. The Interrupt Sense Control bits in the
External Interrupt Control Registers – EICRA and EICRB – defines whether the external inter-
rupt is activated on rising or falling edge or level sensed. Activity on any of these pins will trigger
an interrupt request even if the pin is enabled as an output. This provides a way of generating a
software interrupt.
11.0.4
External Interrupt Flag Register – EIFR
Bit
7
6
5
4
3
2
1
0
INTF7
INTF6
INTF5
R/W
0
INTF4
R/W
0
INTF3
R/W
0
INTF2
R/W
0
INTF1
R/W
0
IINTF0
R/W
0
EIFR
Read/Write
Initial Value
R/W
0
R/W
0
• Bits 7..0 – INTF7 - INTF0: External Interrupt Flags 7 - 0
When an edge or logic change on the INT7:0 pin triggers an interrupt request, INTF7:0 becomes
set (one). If the I-bit in SREG and the corresponding interrupt enable bit, INT7:0 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 INT7:0 are configured as level interrupt. Note that when entering sleep
mode with the INT3:0 interrupts disabled, the input buffers on these pins will be disabled. This
may cause a logic change in internal signals which will set the INTF3:0 flags. See “Digital Input
Enable and Sleep Modes” on page 77 for more information.
11.0.5
Pin Change Interrupt Control Register - PCICR
Bit
7
6
5
4
–
R
0
3
–
R
0
2
–
R
0
1
–
R
0
0
–
R
0
PCIE0
R/W
0
PCICR
Read/Write
Initial Value
R
0
R
0
• 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 Interrupt Vector. PCINT7..0 pins are enabled individually by the PCMSK0 Register.
11.0.6
Pin Change Interrupt Flag Register – PCIFR
Bit
7
6
5
4
–
R
0
3
–
R
0
2
–
R
0
1
–
R
0
0
–
R
0
PCIF0
R/W
0
PCIFR
Read/Write
Initial Value
R
0
R
0
• Bit 0 – PCIF0: Pin Change Interrupt Flag 0
When a logic change on any PCINT7..0 pin triggers an interrupt request, PCIF0 becomes set
(one). If the I-bit in SREG and the PCIE0 bit in EIMSK are set (one), the MCU will jump to the
97
7593A–AVR–02/06
ATMEL [ ATMEL ]
