Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller TQFP 64 (14x14) 8-Bit 20 MHz I/O number 54

ATmega169A/PA/329A/PA/649A/P/3290A/PA/6490A/P [DATASHEET]

8284E–AVR–02/2013

8.6.2 EEARH and EEARL – EEPROM address register Atmel

ATmega329A/329PA/3290A/3290PA/649A/649P/6490A/6490P

• Bits 15:11 – Reserved

These bits are reserved bits in the

ATmega329A/329PA/3290A/3290PA/649A/649P/6490A/6490P and will always read as zero.

• Bits 10:0 – EEAR10:0: EEPROM address

The EEPROM Address Registers – EEARH and EEARL specify the EEPROM address in the 1/2K bytes EEPROM

space. The EEPROM data bytes are addressed linearly between 0 and 1023/2047. The initial value of EEAR is

undefined. A proper value must be written before the EEPROM may be accessed.

Note: 1. EEAR10 is only valid for ATmega649A/649P/6490A/6490P.

8.6.3 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.

8.6.4 EECR – EEPROM control register

• Bits 7:4 – Res: Reserved bits

These bits are reserved bits and will always read as zero.

• Bit 3 – EERIE: EEPROM Ready Interrupt Enable

Writing EERIE to one enables the EEPROM Ready Interrupt if the I bit in SREG is set. Writing EERIE to zero dis-

ables the interrupt. The EEPROM Ready interrupt generates a constant interrupt when EEWE is cleared.

• Bit 2 – EEMWE: EEPROM Master Write Enable

The EEMWE bit determines whether setting EEWE to one causes the EEPROM to be written. When EEMWE is

set, setting EEWE within four clock cycles will write data to the EEPROM at the selected address If EEMWE is

zero, setting EEWE will have no effect. When EEMWE has been written to one by software, hardware clears the bit

to zero after four clock cycles. See the description of the EEWE bit for an EEPROM write procedure.

Bit 1514131211 10 9 8

0x22 (0x42)

– – – – – EEAR10

(1)

EEAR9 EEAR8 EEARH

0x21 (0x41) EEAR7 EEAR6 EEAR5 EEAR4 EEAR3 EEAR2 EEAR1 EEAR0 EEARL

76543 2 1 0

Read/WriteRRRRRR/WR/WR/W

R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 X X X

XXXXX X X X

Bit 76543210

0x20 (0x40) MSB LSB EEDR

Read/Write 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 0

Bit 76543210

0x1F (0x3F)

– – – – EERIE EEMWE EEWE EERE EECR

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

Initial Value000000X0