ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 90

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

External Interrupt Mask
Register – EIMSK
External Interrupt Flag
Register – EIFR
90
ATmega64(L)
• Bits 7..4 – INT7 - INT0: External Interrupt Request 7 - 0 Enable
When an INT7 - INT4 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 Con-
trol bits in the External Interrupt Control Registers – EICRA and EICRB defines whether
the External Interrupt 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.
• 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 inter-
nal signals which will set the INTF3:0 flags. See “Digital Input Enable and Sleep Modes”
on page 68 for more information.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
INTF7
INT7
R/W
R/W
7
0
7
0
INTF6
INT6
R/W
R/W
6
0
6
0
INTF5
INT5
R/W
R/W
5
0
5
0
INTF4
INT4
R/W
R/W
4
0
4
0
INTF3
INT3
R/W
R/W
3
0
3
0
INTF2
INT2
R/W
R/W
2
0
2
0
INTF1
INT1
R/W
R/W
1
0
1
0
INTF0
INT0
R/W
R/W
0
0
0
0
2490G–AVR–03/04
EIMSK
EIFR