Datasheet

7734Q–AVR–02/12

AT90PWM81/161

4.3.2 EEARH and EEARL - EEPROM Address Registers

• Bits 15..9 – Reserved Bits

These bits are reserved bits in the AT90PWM81/161 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.

4.3.3 EEDR - EEPROM Data Register

• 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.

4.3.4 EECR - EEPROM Control Register

• Bits 7 – NVMBSY: Non-volatile memory busy

The NVMBSY bit is a status bit that indicates that the NVM memory (FLASH, EEPROM, Lock-

bits) is busy programming. Once a program operation is started, the bit will be set and it remains

set until the program operation is completed.

Bits 6 – EEPAGE: EEPROM page access (multiple bytes access mode)

Writing EEPAGE to one enables the multiple bytes access mode. That means that several bytes

can be programmed simultaneously into the EEPROM. When the EEPAGE bit has been written

to one, the EEPAGE bit remains set until an EEPROM program operation is completed. Alterna-

tively the bit is cleared when the temporary EEPROM buffer is flushed in software (see EEPMn

bits description). Any write to EEPAGE while EEPE is one will be ignored. See

Section “Program multiple bytes in one Atomic operation”, page 21 for details on how to load

data into the temporary EEPROM page and the usage of the EEPAGE bit.

Bit 1514131211 10 9 8

––––– – –EEAR8EEARH

EEAR7 EEAR6 EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 EEARL

76543 2 10

Read/Write R R R R R R R R/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

XXXXX X XX

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 Value00000000

Bit 765432 10

NVMBSY EEPAGE EEPM1 EEPM0 EERIE EEMWE EEWE EERE EECR

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value X X X X 0 0 X 0