ATmega168 Atmel Corporation, ATmega168 Datasheet - Page 68
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ATmega168
Manufacturer Part Number
ATmega168
Description
Manufacturer
Atmel Corporation
Specifications of ATmega168
Flash (kbytes)
16 Kbytes
Pin Count
32
Max. Operating Frequency
20 MHz
Cpu
8-bit AVR
# Of Touch Channels
16
Hardware Qtouch Acquisition
No
Max I/o Pins
23
Ext Interrupts
24
Usb Speed
No
Usb Interface
No
Spi
2
Twi (i2c)
1
Uart
1
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)
1
Eeprom (bytes)
512
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
3
Output Compare Channels
6
Input Capture Channels
1
Pwm Channels
6
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
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13.2.2
13.2.3
2545T–AVR–05/11
EIMSK – External interrupt mask register
EIFR – External interrupt flag register
• Bit 7..2 – Res: Reserved bits
These bits are unused bits in the Atmel ATmega48/88/168, and will always read as zero.
• Bit 1 – INT1: External interrupt request 1 enable
When the INT1 bit is set (one) and the I-bit in the status register (SREG) is set (one), the exter-
nal pin interrupt is enabled. The interrupt sense control1 bits 1/0 (ISC11 and ISC10) in the
external interrupt control register A (EICRA) define whether the external interrupt is activated on
rising and/or falling edge of the INT1 pin or level sensed. Activity on the pin will cause an inter-
rupt request even if INT1 is configured as an output. The corresponding interrupt of external
interrupt request 1 is executed from the INT1 interrupt vector.
• Bit 0 – INT0: External interrupt request 0 enable
When the INT0 bit is set (one) and the I-bit in the status register (SREG) is set (one), the exter-
nal pin interrupt is enabled. The interrupt sense Control0 bits 1/0 (ISC01 and ISC00) in the
external interrupt control register A (EICRA) define whether the external interrupt is activated on
rising and/or falling edge of the INT0 pin or level sensed. Activity on the pin will cause an inter-
rupt request even if INT0 is configured as an output. The corresponding interrupt of external
interrupt request 0 is executed from the INT0 interrupt vector.
• Bit 7..2 – Res: Reserved bits
These bits are unused bits in the ATmega48/88/168, and will always read as zero.
• Bit 1 – INTF1: External interrupt flag 1
When an edge or logic change on the INT1 pin triggers an interrupt request, INTF1 becomes set
(one). If the I-bit in SREG and the INT1 bit in EIMSK are set (one), the MCU will jump to the cor-
responding 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. This flag is always cleared
when INT1 is configured as a level interrupt.
• Bit 0 – INTF0: External interrupt flag 0
When an edge or logic change on the INT0 pin triggers an interrupt request, INTF0 becomes set
(one). If the I-bit in SREG and the INT0 bit in EIMSK are set (one), the MCU will jump to the cor-
responding 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. This flag is always cleared
when INT0 is configured as a level interrupt.
Bit
0x1D (0x3D)
Read/write
Initial value
Bit
0x1C (0x3C)
Read/write
Initial value
R
R
7
–
0
7
–
0
R
R
6
–
0
6
–
0
R
R
5
–
0
5
–
0
R
R
4
–
0
4
–
0
R
R
3
–
0
3
–
0
ATmega48/88/168
R
R
2
–
0
2
–
0
INTF1
INT1
R/W
R/W
1
0
1
0
INTF0
INT0
R/W
R/W
0
0
0
0
EIMSK
EIFR
68