CY28341
Table 4. Byte Read and Byte Write Protocol
Byte Write Protocol
Byte Read Protocol
Description
Start
Bit
1
Description
Start
Bit
1
2:8
9
Slave address – 7 bits
Write
2:8
9
Slave address – 7 bits
Write
10
Acknowledge from slave
10
Acknowledge from slave
11:18
Command Code – 8 bits “1xxxxxxx” stands for
byte operationbit[6:0] of the command code
represents the offset of the byte to be accessed
11:18
Command Code – 8 bits “1xxxxxxx” stands for
byte operationbit[6:0] of the command code
represents the offset of the byte to be accessed
19
20:27
28
Acknowledge from slave
Byte Count – 8 bits
Acknowledge from slave
Stop
19
20
Acknowledge from slave
Repeat start
21:27
28
Slave address – 7 bits
Read
29
29
Acknowledge from slave
Data byte from slave – 8 bits
Not Acknowledge
Stop
30:37
38
39
Serial Control Registers
Byte 0: Frequency Select Register
Bit
7
@Pup
0
Pin#
Name
Reserved
FS2
Description
Reserved
6
H/W Setting
H/W Setting
H/W Setting
0
21
10
1
For Selecting Frequencies see Table 1.
For Selecting Frequencies see Table 1.
For Selecting Frequencies see Table 1.
5
FS1
4
FS0
3
If this bit is programmed to “1,” it enables Write to bits (6:4,1) for
selecting the frequency via software (SMBus). If this bit is
programmed to a “0,” it enables only Read of bits (6:4,1), which
reflects the hardware setting of FS(0:3).
2
H/W Setting
11
SELSDR_DDR Only for reading the hardware setting of the SDRAM interface
mode, status of SELSDR_DDR# strapping.
1
0
H/W Setting
H/W Setting
20
7
FS3
For Selecting frequencies see Table 1ꢁ
SELP4_K7
Only for reading the hardware setting of the CPU interface mode,
status of SELP4_K7# strapping.
Byte 1: CPU Clocks Register
Bit @Pup Pin#
Name
Description
7
6
5
4
3
0
1
1
1
1
MODE
0 = Down Spread. 1 = Center Spread. See Table 9.
1 = Enable (default). 0 = Disable
SSCG
SST1
SST0
Select spread bandwidth. See Table 9.
Select spread bandwidth. See Table 9.
48,49 CPUCS_T, CPUCS_C 1 = output enabled (running). 0 = output disabled asynchronously in a LOW
state.
2
1
53,52
CPUT/CPUOD_T
CPUC/CPUOD_C
1 = output enabled (running). 0 = output disable.
Rev 1.0,November 20, 2006
Page 5 of 19
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