CY28301

Rev 1.0, November 27, 2006

Page 3 of 13

Serial Data Interface

The CY28301 features a two-pin, serial data interface that can

be used to configure internal register settings that control

particular device functions.

Data Protocol

The clock driver serial protocol supports byte/word Write,

byte/word Read, block Write, and block Read operations from

the controller. For block Write/Read operation, the bytes must

be accessed in sequential order from lowest to highest byte

with the ability to stop after any complete byte has been trans-

ferred. For byte/word Write and byte Read operations, the

system controller can access individual indexed bytes. The

offset of the indexed byte is encoded in the command code.

The definition for the command code is defined as follows.

Table 1. Command Code Definition

Bit

Descriptions

7

0 = Block Read or block Write operation

1 = Byte/Word Read or byte/word Write operation

6:0

Byte offset for byte/word Read or Write operation. For block Read or Write operations, these bits

need to be set at ‘0000000.’

Table 2. Block Read and Block Write Protocol

Block Write Protocol

Block Read Protocol

Bit

Description

Bit

Description

1Start

1Start

2:8

Slave address – 7 bits

2:8

Slave address – 7 bits

9Write

9Write

10

Acknowledge from slave

10

Acknowledge from slave

11:18

Command code – 8-bits

‘00000000’ stands for block operation

11:18

Command code – 8 bits

‘00000000’ stands for block operation

19

Acknowledge from slave

19

Acknowledge from slave

20:27

Byte count – 8 bits

20

Repeat start

28

Acknowledge from slave

21:27

Slave address – 7 bits

29:36

Data byte 0 – 8 bits

28

Read

37

Acknowledge from slave

29

Acknowledge from slave

38:45

Data byte 1 – 8 bits

30:37

Byte count from slave –8 bits

46

Acknowledge from slave

38

Acknowledge

...

Data byte N/Slave acknowledge...

39:46

Data byte from slave – 8 bits

...

Data byte N – 8 bits

47

Acknowledge

...

Acknowledge from slave

48:55

Data byte from slave – 8 bits

...

Stop

56

Acknowledge

...

Data bytes from slave/acknowledge

...

Data byte N from slave – 8 bits

...

Not acknowledge

...

Stop