16
7598H–AVR–07/09
ATtiny25/45/85
5.3.2 EEPROM Address Register High – EEARH
• Bit 7..1 – Res6..0: Reserved Bits
These bits are reserved for future use and will always read as 0 in ATtiny25/45/85.
• Bits 0 – EEAR8: EEPROM Address
The EEPROM Address Register – EEARH – specifies the high EEPROM address in the
128/256/512 bytes EEPROM space. The EEPROM data bytes are addressed linearly between 0
and 127/255/511. The initial value of EEAR is undefined. A proper value must be written before
the EEPROM may be accessed.
5.3.3 EEPROM Address Register – EEARL
• Bits 7..0 – EEAR7..0: EEPROM Address
The EEPROM Address Register – EEARL – specifies the low EEPROM address in the
128/256/512 bytes EEPROM space. The EEPROM data bytes are addressed linearly between 0
and 127/255/511. The initial value of EEAR is undefined. A proper value must be written before
the EEPROM may be accessed.
5.3.4 EEPROM Data Register – EEDR
• Bits 7..0 – EEDR7..0: EEPROM Data
For the EEPROM write operation the EEDR Register contains the data to be written to the
EEPROM in the address given by the EEAR Register. For the EEPROM read operation, the
EEDR contains the data read out from the EEPROM at the address given by EEAR.
5.3.5 EEPROM Control Register – EECR
• Bit 7 – Res: Reserved Bit
This bit is reserved for future use and will always read as 0 in ATtiny25/45/85. For compatibility
with future AVR devices, always write this bit to zero. After reading, mask out this bit.
Bit 76543210
-------EEAR8EEARH
Read/Write RRRRRRRR/W
Initial Value X X X X X X X X
Bit 76543210
EEAR7 EEAR6 EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 EEARL
Read/Write R R R/W R/W R/W R/W R/W R/W
Initial Value X X X X X X X X
Bit 76543210
EEDR7 EEDR6 EEDR5 EEDR4 EEDR3 EEDR2 EEDR1 EEDR0 EEDR
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value X X X X X X X X
Bit 76543210
– – EEPM1 EEPM0 EERIE EEMPE EEPE EERE EECR
Read/Write R R R/W R/W R/W R/W R/W R/W
Initial Value 0 0 X X 0 0 X 0