AT34C02B View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT34C02B

Two-wire Serial EEPROM with Permanent and Reversible Software Write Protect

Atmel Corporation 

Table 9. WP Connected to Vcc

WP Connected to Vcc

Command

R/W Bit

Permanent Write

Protect Register

PSWP

1010

R

X

1010

W

X

Reversible Write

Protect Register

RSWP

X

X

Acknowledgment

from Device

ACK

ACK

Action from Device

Read array

Device Write Protect

Read

PSWP

R

Programmed

X

Read

PSWP

R

Not Programmed

X

Set PSWP

W

Programmed

X

Set PSWP

W

Not Programmed

X

No ACK

ACK

No ACK

ACK

STOP - Indicates permanent write protect register is

programmed

Read out data don't care. Indicates PSWP register is

not programmed

STOP - Indicates permanent write protect register is

programmed

Cannot program write protect registers

Read

RSWP

R

Read

RSWP

R

X

Programmed

X

Not Programmed

Set RSWP

W

X

Programmed

Set RSWP

W

X

Not Programmed

Clear

RSWP

W

Programmed

X

Clear

RSWP

W

Not Programmed

X

No ACK

ACK

No ACK

ACK

No ACK

ACK

STOP - Indicates reversible write protect register is

programmed

Read out data don't care. Indicates RSWP register is

not programmed

STOP - Indicates reversible write protect register is

programmed

Cannot program write protect registers

STOP - Indicates permanent write protect register is

programmed

Cannot write to write protect registers

Read Operations

Read operations are initiated the same way as write operations with the exception that

the read/write select bit in the device address word is set to one. There are three read

operations: current address read, random address read and sequential read.

CURRENT ADDRESS READ: The internal data word address counter maintains the

last address accessed during the last read or write operation, incremented by one. This

address stays valid between operations as long as the chip power is maintained. The

address “roll over” during read is from the last byte of the last memory page to the first

byte of the first page.

Once the device address with the read/write select bit set to one is clocked in and

acknowledged by the EEPROM, the current address data word is serially clocked out.

To end the command, the microcontroller does not respond with an input zero but does

generate a following stop condition (see Figure 13 on page 14).

RANDOM READ: A random read requires a “dummy” byte write sequence to load in the

data word address. Once the device address word and data word address are clocked

in and acknowledged by the EEPROM, the microcontroller must generate another start

condition. The microcontroller now initiates a current address read by sending a device

address with the read/write select bit high. The EEPROM acknowledges the device

address and serially clocks out the data word. To end the command, the microcontroller

12 AT34C02B

3417E–SEEPR–1/07

Share Link: