Datasheet

28
8018P–AVR–08/10
ATmega169P
7.5 General Purpose I/O Registers
The ATmega169P contains three General Purpose I/O Registers. These registers can be used
for storing any information, and they are particularly useful for storing global variables and Sta-
tus Flags. General Purpose I/O Registers within the address range 0x00 - 0x1F are directly bit-
accessible using the SBI, CBI, SBIS, and SBIC instructions.
7.5.1 GPIOR2 – General Purpose I/O Register 2
7.5.2 GPIOR1 – General Purpose I/O Register 1
7.5.3 GPIOR0 – General Purpose I/O Register 0
7.6 EEPROM Register Description
7.6.1 EEARH and EEARL – EEPROM Address Register
• Bits 15:9 – Res: Reserved Bits
These bits are reserved and will always read as zero.
• Bits 8:0 – EEAR8:0: EEPROM Address
The EEPROM Address Registers – EEARH and EEARL specify the EEPROM address in the
512 bytes EEPROM space. The EEPROM data bytes are addressed linearly between 0 and
511. The initial value of EEAR is undefined. A proper value must be written before the EEPROM
may be accessed.
Bit 76543210
0x2B (0x4B) MSB LSB GPIOR2
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
0x2A (0x4A) MSB LSB GPIOR1
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 76543210
0x1E (0x3E) MSB LSB GPIOR0
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value00000000
Bit 151413121110 9 8
0x22 (0x42) –––––––EEAR8EEARH
0x21 (0x41) EEAR7 EEAR6 EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 EEARL
76543210
Read/Write RRRRRRRR/W
R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 X
XXXXXXXX