ATmega48P/88P/168P
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Page
0x1D (0x3D)
0x1C (0x3C)
0x1B (0x3B)
0x1A (0x3A)
0x19 (0x39)
0x18 (0x38)
0x17 (0x37)
0x16 (0x36)
0x15 (0x35)
0x14 (0x34)
0x13 (0x33)
0x12 (0x32)
0x11 (0x31)
0x10 (0x30)
0x0F (0x2F)
0x0E (0x2E)
0x0D (0x2D)
0x0C (0x2C)
0x0B (0x2B)
0x0A (0x2A)
0x09 (0x29)
0x08 (0x28)
0x07 (0x27)
0x06 (0x26)
0x05 (0x25)
0x04 (0x24)
0x03 (0x23)
0x02 (0x22)
0x01 (0x21)
0x0 (0x20)
EIMSK
EIFR
–
–
–
–
–
–
INT1
INT0
70
70
–
–
–
–
–
–
INTF1
INTF0
PCIFR
–
–
–
–
–
PCIF2
PCIF1
PCIF0
Reserved
Reserved
Reserved
TIFR2
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
OCF2B
OCF2A
TOV2
161
138
TIFR1
–
–
ICF1
–
–
OCF1B
OCF1A
TOV1
TIFR0
–
–
–
–
–
OCF0B
OCF0A
TOV0
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
PORTD
DDRD
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
PORTD7
PORTD6
DDD6
PIND6
PORTC6
DDC6
PINC6
PORTB6
DDB6
PINB6
–
PORTD5
DDD5
PIND5
PORTC5
DDC5
PINC5
PORTB5
DDB5
PINB5
–
PORTD4
DDD4
PIND4
PORTC4
DDC4
PINC4
PORTB4
DDB4
PINB4
–
PORTD3
DDD3
PIND3
PORTC3
DDC3
PINC3
PORTB3
DDB3
PINB3
–
PORTD2
DDD2
PIND2
PORTC2
DDC2
PINC2
PORTB2
DDB2
PINB2
–
PORTD1
DDD1
PIND1
PORTC1
DDC1
PINC1
PORTB1
DDB1
PINB1
–
PORTD0
DDD0
PIND0
PORTC0
DDC0
PINC0
PORTB0
DDB0
PINB0
–
91
91
91
90
90
90
90
90
90
DDD7
PIND
PIND7
PORTC
DDRC
–
–
PINC
–
PORTB
DDRB
PORTB7
DDB7
PINB
PINB7
Reserved
Reserved
Reserved
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Note:
1. For compatibility with future devices, reserved bits should be written to zero if accessed. Reserved I/O memory addresses
should never be written.
2. I/O Registers within the address range 0x00 - 0x1F are directly bit-accessible using the SBI and CBI instructions. In these
registers, the value of single bits can be checked by using the SBIS and SBIC instructions.
3. Some of the Status Flags are cleared by writing a logical one to them. Note that, unlike most other AVRs, the CBI and SBI
instructions will only operate on the specified bit, and can therefore be used on registers containing such Status Flags. The
CBI and SBI instructions work with registers 0x00 to 0x1F only.
4. When using the I/O specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used. When addressing I/O
Registers as data space using LD and ST instructions, 0x20 must be added to these addresses. The ATmega48P/88P/168P
is a complex microcontroller with more peripheral units than can be supported within the 64 location reserved in Opcode for
the IN and OUT instructions. For the Extended I/O space from 0x60 - 0xFF in SRAM, only the ST/STS/STD and
LD/LDS/LDD instructions can be used.
5. Only valid for ATmega88P/168P.
12
8025MS–AVR–6/11
ATMEL [ ATMEL ]
