9

DS1683

Total-Elapsed-Time and Event Recorder with Alarm

If the Password Value has been changed from the factory

default setting, the user has to enter this new password

value into the PWE registers after a power cycle in order

to unlock the memory again.

See Figure 3 for examples of writing the 4-byte Password

Value and the 4-byte Password Entry value.

User Memory

The DS1683 has 16 bytes of user-programmable,

EEPROM memory. User memory is set to read-only if

the correct password is not entered into the Password

Entry Bytes. If the correct password is entered into the

Password Entry Bytes, the data can be written to the User

command.

COMMUNICATIONS KEY

S

NOTES

P

Sr

A

N

START

8-BIT ADDRESS OR DATA

REPEATED

START

STOP

ACK

NOT

ACK

WHITE BOXES INDICATE THE MASTER IS

CONTROLLING SDA

SHADED BOXES INDICATE THE SLAVE IS

CONTROLLING SDA

WRITE THE 4-BYTE PASSWORD VALUE (REGISTERS 1Ah THROUGH 1Dh) WITH A SINGLE TRANSACTION TO SLAVE ADDRESS D6h

WRITE THE 4-BYTE PASSWORD ENTRY (REGISTERS 02h THROUGH 05h) WITH A SINGLE TRANSACTION TO SLAVE ADDRESS D6h

XXXXXXXX

S

1101

10

AA

BYTE 1

A

BYTE 4

AP

1) ALL BYTES ARE SENT MOST SIGNIFICANT BIT FIRST.

2) THE FIRST BYTE SENT AFTER A START CONDITION

IS ALWAYS THE SLAVE ADDRESS FOLLOWED BY THE

READ/WRITE BIT.

1

00 00 11 0

0

1

BYTE 2

A

S

1101

10

AA

BYTE 1

A

1

00 00 01 0

0

0

BYTE 2

A

BYTE 3

A

BYTE 4

AP

BYTE 3

A