ASAHI KASEI

[AK4342]

MS0506-E-02

2006/07

- 30 -

2. I

The AK4342 supports a fast-mode I

1. WRITE Operations

Figure 22 shows the data transfer sequence for the I

HIGH to LOW transition on the SDA line while SCL is HIGH indicates a START condition (Figure 28). After the

START condition, a slave address is sent. This address is 7 bits long followed by an eighth bit that is a data direction bit

(R/W). The most significant five bits of the slave address are fixed as “001000”. The next one bit is CAD0 (device address

bit). This bit identifies the specific device on the bus. The hard-wired input pin (CAD0 pin) set these device address bits

(Figure 23). If the slave address matches that of the AK4342, the AK4342 generates an acknowledge and the operation is

executed. The master must generate the acknowledge-related clock pulse and release the SDA line (HIGH) during the

acknowledge clock pulse (Figure 29). A R/W bit value of “1” indicates that the read operation is to be executed. A “0”

indicates that the write operation is to be executed.

The second byte consists of the control register address of the AK4342. The format is MSB first, and those most

significant 3-bits are fixed to zeros (Figure 24). The data after the second byte contains control data. The format is MSB

first, 8bits (Figure 25). The AK4342 generates an acknowledge after each byte has been received. A data transfer is

always terminated by a STOP condition generated by the master. A LOW to HIGH transition on the SDA line while SCL

is HIGH defines a STOP condition (Figure 28).

The AK4342 can perform more than one byte write operation per sequence. After receipt of the third byte the AK4342

generates an acknowledge and awaits the next data. The master can transmit more than one byte instead of terminating the

write cycle after the first data byte is transferred. After receiving each data packet the internal 5-bit address counter is

incremented by one, and the next data is automatically taken into the next address. If the address exceeds 09H prior to

generating the stop condition, the address counter will “roll over” to 00H and the previous data will be overwritten.

The data on the SDA line must remain stable during the HIGH period of the clock. The HIGH or LOW state of the data

line can only change when the clock signal on the SCL line is LOW (Figure 30) except for the START and STOP

conditions.

SDA

Slave

Address

S

S

T

A

R

T

R/W="0"

A

C

K

Sub

Address(n)

A

C

K

Data(n)

A

C

K

Data(n+1)

A

C

K

A

C

K

Data(n+x)

A

C

K

P

S

T

O

P

Figure 22. Data Transfer Sequence at the I

0

0

1

0

0

0

CAD0

R/W

Figure 23. The First Byte

0

0

0

A4

A3

A2

A1

A0

Figure 24. The Second Byte

D7

D6

D5

D4

D3

D2

D1

D0

Figure 25. Byte Structure after the second byte