W311_05 Datasheet, PDF (3/19 Pages) Cypress Semiconductor – FTG for VIA™ Pro-266 DDR Chipset

W311
Serial Data Interface
The W311 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, system
controller can access individual indexed byte. The offset of the
indexed byte is encoded in the command code.
The definition for the command code is defined in Table 2.
Table 1.
Bit
7
6:0
Descriptions
0 = Block read or block write operation
1 = Byte/Word read or byte/word write operation
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
Bit
Description
1
Start
2:8 Slave address – 7 bits
9
Write
10
Acknowledge from slave
11:18 Command Code – 8 bits
‘00000000’ stands for block operation
19
Acknowledge from slave
20:27 Byte Count – 8 bits
28
Acknowledge from slave
29:36 Data byte 0 – 8 bits
37
Acknowledge from slave
38:45 Data byte 1 – 8 bits
46
Acknowledge from slave
...
Data Byte N/Slave Acknowledge...
...
Data Byte N – 8 bits
...
Acknowledge from slave
...
Stop
Bit
1
2:8
9
10
11:18
19
20
21:27
28
29
30:37
38
39:46
47
48:55
56
...
...
...
...
Block Read Protocol
Description
Start
Slave address – 7 bits
Write
Acknowledge from slave
Command Code – 8 bits
‘00000000’ stands for block operation
Acknowledge from slave
Repeat start
Slave address – 7 bits
Read
Acknowledge from slave
Byte count from slave – 8 bits
Acknowledge
Data byte from slave – 8 bits
Acknowledge
Data byte from slave – 8 bits
Acknowledge
Data bytes from slave/Acknowledge
Data byte N from slave – 8 bits
Not Acknowledge
Stop
Document #: 38-07703 Rev. **
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