C9531_04 Datasheet, PDF (3/10 Pages) Cypress Semiconductor – PCIX I/O System Clock Generator with EMI Control Features

C9531
Serial Data Interface
Data Protocol
To enhance the flexibility and function of the clock synthesizer,
a two-signal serial interface is provided. Through the Serial
Data Interface, various device functions, such as individual
clock output buffers, can be individually enabled or disabled.
The registers associated with the Serial Data Interface
initializes to their default setting upon power-up, and therefore
use of this interface is optional. Clock device register changes
are normally made upon system initialization, if any are
required.
The clock driver serial protocol accepts block write a opera-
tions from the controller. The bytes must be accessed in
sequential order from lowest to highest byte (most significant
bit first) with the ability to stop after any complete byte has
been transferred. The C9531 does not support the Block Read
function.
The block write protocol is outlined in Table 2. The addresses
are listed in Table 3.
Table 2. Block Read and Block Write Protocol
Bit
1
2:8
9
10
11:18
19
20:27
28
29:36
37
38:45
46
....
....
....
....
....
....
Block Write Protocol
Description
Start
Slave address – 7 bits
Write = 0
Acknowledge from slave
Command Code – 8 bits
'00000000' stands for block operation
Acknowledge from slave
Byte Count – 8 bits
Acknowledge from slave
Data byte 1 – 8 bits
Acknowledge from slave
Data byte 2 – 8 bits
Acknowledge from slave
......................
Data Byte (N–1) – 8 bits
Acknowledge from slave
Data Byte N – 8 bits
Acknowledge from slave
Stop
Table 3. SMBus Address Selection Table
SMBus Address of the Device
DE
DC
DA
D8
D6
D4
D0
D2
IA0 Bit (Pin 10)
0
1
0
1
0
1
0
1
IA1 Bit (Pin 11)
0
0
1
1
0
0
1
1
IA2 Bit (Pin 12)
0
0
0
0
1
1
1
1
Document #: 38-07034 Rev. *E
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