ATA8741 ATMEL Corporation, ATA8741 Datasheet - Page 38

• Manufacturer Part Number: ATA8741
• Manufacturer: ATMEL Corporation

13.5
13.5.1
13.5.2
13.5.3
13.5.4
38
Register Description
ATA8741
EEARH – EEPROM Address Register
EEARL – EEPROM Address Register
EEDR – EEPROM Data Register
EECR – EEPROM Control Register
• Bits 7..1 – Res: Reserved Bits
These bits are reserved bits in the ATtiny24/44/84 and will always read as zero.
• Bit 0 – EEAR8: EEPROM Address
The EEPROM Address Register – EEARH – specifies the most significant bit for EEPROM
address in the 512 bytes EEPROM space for Tiny84. This bit is reserved bit in the ATtiny24/44
and will always read as zero. The initial value of EEAR is undefined. A proper value must be
written before the EEPROM may be accessed.
• Bits 7..0 – EEAR7..0: EEPROM Address
The EEPROM Address Register – EEARL – specifies the EEPROM address. In the 128 bytes
EEPROM space in ATiny24 bit 7 is reserved and always read as zero. The EEPROM data bytes
are addressed linearly between 0 and 128/256/512. The initial value of EEAR is undefined. A
proper value must be written before the EEPROM may be accessed.
• 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.
Bit
0x1F (0x3F)
Read/Write
Initial Value
Bit
0x1E (0x3E)
Read/Write
Initial Value
Bit
0x1D (0x3D)
Read/Write
Initial Value
Bit
0x1C (0x3C)
Read/Write
Initial Value
EEAR7
EEDR7
R/W
R/W
R
X
R
7
–
0
7
7
0
7
–
0
EEAR6
EEDR6
R/W
R/W
R
R
6
–
0
6
X
6
0
6
–
0
EEAR5
EEDR5
EEPM1
R/W
R/W
R/W
R
X
X
5
–
0
5
5
0
5
EEPM0
EEAR4
EEDR4
R/W
R/W
R/W
R
X
X
4
–
0
4
4
0
4
EEAR3
EEDR3
EERIE
R/W
R/W
R/W
R
X
3
–
0
3
3
0
3
0
EEMPE
EEAR2
EEDR2
R/W
R/W
R/W
R
X
2
–
0
2
2
0
2
0
EEAR1
EEDR1
EEPE
R/W
R/W
R/W
R
X
X
1
–
0
1
1
0
1
EEAR8
EEAR0
EEDR0
EERE
R/W
R/W
R/W
R/W
9140B–INDCO–07/09
X
X
0
0
0
0
0
0
EEARH
EEARL
EEDR
EECR