ATmega328P datasheet(20/345 Pages) ATMEL

20 / 345 page

7810A–AVR–11/09

ATmega328P [Preliminary]

Some of the Status Flags are cleared by writing a logical one to them. Note that, unlike most

other AVRs, the CBI and SBI instructions will only operate on the specified bit, and can therefore

be used on registers containing such Status Flags. The CBI and SBI instructions work with reg-

isters 0x00 to 0x1F only.

The I/O and peripherals control registers are explained in later sections.

7.5.1

General Purpose I/O Registers

The ATmega328P contains three General Purpose I/O Registers. These registers can be used

for storing any information, and they are particularly useful for storing global variables and Sta-

tus Flags. General Purpose I/O Registers within the address range 0x00 - 0x1F are directly

bit-accessible using the SBI, CBI, SBIS, and SBIC instructions.

7.6

7.6.1

EEARH and EEARL – The EEPROM Address Register

• Bits 15..9 – Res: Reserved Bits

These bits are reserved bits in the ATmega328P 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

256/512/512/1K bytes EEPROM space. The EEPROM data bytes are addressed linearly

between 0 and 255/511/511/1023. The initial value of EEAR is undefined. A proper value must

be written before the EEPROM may be accessed.

EEAR8 is an unused bit in ATmega328P and must always be written to zero.

7.6.2

EEDR – The 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.

Bit

151413

1110

0x22 (0x42)

––

–

EEAR8

EEARH

0x21 (0x41)

EEAR7

EEAR6

EEAR5

EEAR4

EEAR3

EEAR2

EEAR1

EEAR0

EEARL

Read/Write

R/W

Initial Value

Bit

0x20 (0x40)

MSB

LSB

EEDR

Read/Write

R/W

Initial Value

ATmega328P Datasheet(PDF) 20 Page - ATMEL Corporation

ATmega328P Datasheet(HTML) 20 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL