ATMEGA168-20PI Atmel, ATMEGA168-20PI Datasheet - Page 68

• Manufacturer Part Number: ATMEGA168-20PI
• Description: IC AVR MCU 16K 20MHZ 28DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA168-20PI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

12.2.4
12.2.5
68
ATmega48/88/168
PCICR – Pin Change Interrupt Control Register
PCIFR – Pin Change Interrupt Flag Register
• Bit 7..3 - Res: Reserved Bits
These bits are unused bits in the ATmega48/88/168, and will always read as zero.
• 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..3 - Res: Reserved Bits
These bits are unused bits in the ATmega48/88/168, and will always read as zero.
• Bit 2 - PCIF2: Pin Change Interrupt Flag 2
When a logic change on any PCINT23..16 pin triggers an interrupt request, PCIF2 becomes set
(one). If the I-bit in SREG and the PCIE2 bit in PCICR are set (one), the MCU will jump to the
corresponding Interrupt Vector. The flag is cleared when the interrupt routine is executed. Alter-
natively, the flag can be cleared by writing a logical one to it.
• Bit 1 - PCIF1: Pin Change Interrupt Flag 1
When a logic change on any PCINT14..8 pin triggers an interrupt request, PCIF1 becomes set
(one). If the I-bit in SREG and the PCIE1 bit in PCICR are set (one), the MCU will jump to the
corresponding Interrupt Vector. The flag is cleared when the interrupt routine is executed. Alter-
natively, the flag can be cleared by writing a logical one to it.
Bit
(0x68)
Read/Write
Initial Value
Bit
0x1B (0x3B)
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
3
–
R
0
3
–
R
0
PCIE2
PCIF2
R/W
R/W
2
0
2
0
PCIE1
PCIF1
R/W
R/W
1
0
1
0
PCIE0
PCIF0
R/W
R/W
0
0
0
0
2545S–AVR–07/10
PCICR
PCIFR