BR34L02FV-W

Technical Note

10/17

www.rohm.com

2009.04 - Rev.A

© 2009 ROHM Co., Ltd. All rights reserved.

WRITE COMMAND

SLAVE

DATA

ADDRESS

WORD

ADDRESS

SLAVE

ADDRESS

SLAVE

ADDRESS

SLAVE

ADDRESS

S

T

A

R

T

S

Ｔ

O

P

A

C

K

H

S

T

A

R

T

S

T

A

R

T

A

C

K

H

S

T

A

R

T

A

C

K

H

S

T

A

R

T

A

C

K

L

A

C

K

L

A

C

K

L

S

Ｔ

O

P

After the internal write cycle

is completed, ACK will be returned

(ACK=Low). Then input next

Word Address and data.

During the internal write cycle,

no ACK will be returned.

(ACK=High)

・・・

●

Software Reset

Execute software reset in the event that the device is in an unexpected state after power up and/or the command input

needs to be reset. Below are three types(Fig.39 –(a), (b), (c)) of software reset:

・

・

During this time the device may pull the SDA line Low for Acknowledge or the outputting of read data.

・

If the Master sets the SDA line to High, it will conflict with the device output Low, which can cause current overload and

result in instantaneous power down, which may damage the device.

●

Acknowledge polling

Since the IC ignores all input commands during the internal write cycle, no ACK signal will be returned.

When the Master sends the next command after the Write command, if the device returns an ACK signal it means that the

program is completed. No ACK signal indicates that the device is still busy.

Using Acknowledge polling decreases the waiting time by tWR=5ms.

When operating Write or Current Read after Write, first transmit the Slave address (R/W is"High" or "Low"). After the device

returns the ACK signal continue word address input or data output.

1

2

13

14

SCL

DUMMY CLOCK×14

START×2

SCL

SCL

Fig.39-(a) DUMMY CLOCK×14 + START+START

1

2

3

8

9

7

Fig.39-(c) START×9

*

COMMAND starts with start condition.

2

1

8

9

DUMMY CLOCK×9

START

Fig.39-(b) START + DUMMY CLOCK×9 + START

START

COMMAND

COMMAND

COMMAND

COMMAND

COMMAND

COMMAND

START×9

SDA

SDA

SDA

THE FIRST WRITE COMMAND

tWR

THE SECOND WRITE COMMAND

・・・

tWR

Fig.40 Successive Write Operation By Acknowledge Polling