8-bit AVR Microcontrollers

EEPROM Address Register Low and High Byte

The EEARL and EEARH register pair represents the 16-bit value, EEAR. The low byte [7:0] (suffix L) is accessible at the original offset. The high byte [15:8] (suffix H) can be accessed at offset + 0x01. For more details on reading and writing 16-bit registers, refer to accessing 16-bit registers in the section above.

When addressing I/O registers as data space using LD and ST instructions, the provided offset must be used. When using the I/O specific commands IN and OUT, the offset is reduced by 0x20, resulting in an I/O address offset within 0x00 - 0x3F.

The device is a complex microcontroller with more peripheral units than can be supported within the 64 locations reserved in Opcode for the IN and OUT instructions. For the extended I/O space from 0x60 in SRAM, only the ST/STS/STD and LD/LDS/LDD instructions can be used.

Name:
EEARL and EEARH
Offset:
0x41
Reset:
0xXX
Access:
When addressing as I/O Register: address offset is 0x21
Bit15141312111098
EEAR[9:8]
AccessR/WR/W
Resetxx
Bit76543210
EEAR[7:0]
AccessR/WR/WR/WR/WR/WR/WR/WR/W
Resetxxxxxxxx

Bits 9:0 – EEAR[9:0]: EEPROM Address

EEPROM Address

The EEPROM Address Registers, EEARH and EEARL, specify the EEPROM address in the 1 KB EEPROM space. The EEPROM data bytes are addressed linearly between 0 and 1023. The initial value of EEAR is undefined. A proper value must be written before the EEPROM may be accessed.