ATmega1281 Atmel Corporation, ATmega1281 Datasheet - Page 114

• Manufacturer Part Number: ATmega1281
• Manufacturer: Atmel Corporation

Specifications of ATmega1281

• Flash (kbytes): 128 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 54
• Ext Interrupts: 17
• Usb Speed: No
• Usb Interface: No
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 6
• Output Compare Channels: 16
• Input Capture Channels: 2
• Pwm Channels: 8
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

15.2.2
2549N–AVR–05/11
EICRB – External Interrupt Control Register B
Table 15-1.
Note:
Table 15-2.
• Bits 7:0 – ISC71, ISC70 - ISC41, ISC40: External Interrupt 7 - 4 Sense Control Bits
The External Interrupts 7 - 4 are activated by the external pins INT7:4 if the SREG I-flag and the
corresponding interrupt mask in the EIMSK is set. The level and edges on the external pins that
activate the interrupts are defined in
before detecting edges. If edge or toggle interrupt is selected, pulses that last longer than one
clock period will generate an interrupt. Shorter pulses are not guaranteed to generate an inter-
rupt. Observe that CPU clock frequency can be lower than the XTAL frequency if the XTAL
divider is enabled. If low level interrupt is selected, the low level must be held until the comple-
tion of the currently executing instruction to generate an interrupt. If enabled, a level triggered
interrupt will generate an interrupt request as long as the pin is held low.
Table 15-3.
Note:
Bit
(0x6A)
Read/Write
Initial Value
ISCn1
ISCn1
Symbol
t
0
0
1
1
0
0
1
1
INT
1. n = 3, 2, 1or 0.
1. n = 7, 6, 5 or 4.
ISCn0
When changing the ISCn1/ISCn0 bits, the interrupt must be disabled by clearing its Interrupt
Enable bit in the EIMSK Register. Otherwise an interrupt can occur when the bits are changed.
When changing the ISCn1/ISCn0 bits, the interrupt must be disabled by clearing its Interrupt
Enable bit in the EIMSK Register. Otherwise an interrupt can occur when the bits are changed.
ISCn0
Minimum pulse width for asynchronous
0
1
0
1
0
1
0
1
Asynchronous External Interrupt Characteristics
Interrupt Sense Control
Interrupt Sense Control
ISC71
R/W
7
0
The falling edge between two samples of INTn generates an interrupt request
The rising edge between two samples of INTn generates an interrupt request
external interrupt
ISC70
R/W
The falling edge of INTn generates asynchronously an interrupt request
The rising edge of INTn generates asynchronously an interrupt request
Parameter
6
0
Any edge of INTn generates asynchronously an interrupt request
Any logical change on INTn generates an interrupt request
ATmega640/1280/1281/2560/2561
ISC61
The low level of INTn generates an interrupt request
The low level of INTn generates an interrupt request
R/W
5
0
(1)
Table
(1)
ISC60
R/W
4
0
15-3. The value on the INT7:4 pins are sampled
Description
ISC51
Description
R/W
Condition
3
0
ISC50
R/W
2
0
Min
ISC41
R/W
1
0
Typ
50
ISC40
R/W
0
0
Max
EICRB
Units
ns
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