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W196 Datasheet, PDF (6/11 Pages) Cypress Semiconductor – Spread Spectrum FTG for 440BX and VIA Apollo Pro-133
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W196
Writing Data Bytes
Each bit in the data bytes control a particular device function
except for the “reserved” bits which must be written as a logic
0. Bits are written MSB (most significant bit) first, which is bit
7. Table 4 gives the bit formats for registers located in Data
Bytes 3–6.
Table 5 details additional frequency selections that are
available through the serial data interface.
Table 6 details the select functions for Byte 3, bits 1 and 0.
Table 4. Data Bytes 3–6 Serial Configuration Map
Affected Pin
Bit Control
Bit(s) Pin No. Pin Name
Control Function
0
1
Data Byte 3
7
--
--
SEL_3
Refer to Table 5
6
--
--
SEL_2
Refer to Table 5
5
--
--
SEL_1
Refer to Table 5
4
--
--
SEL_0
Refer to Table 5
3
--
--
Frequency Table
Selection
Frequency Controlled Frequency Controlled
by external FS0:1 pins by BYT3 SEL_(3:0)
(Table 1)
Table 5
2
--
--
(Reserved)
--
--
1–0
--
--
Bit 1 Bit 0 Function (See Table 6 for function details)
0
0 Spread Spectrum Off
0
1 Test Mode
1
0 Spread Spectrum On (default)
1
1 All Outputs Three-stated
Data Byte 4
7
--
--
(Reserved)
--
--
6
14
24/48MHz Clock Output Disable
Low
Active
5
--
--
(Reserved)
--
--
4
--
--
(Reserved)
--
--
3
--
--
(Reserved)
--
--
2
21
CPU1 Clock Output Disable
Low
Active
1
--
--
(Reserved)
--
--
0
22
CPU0 Clock Output Disable
Low
Active
Data Byte 5
7
4
PCI_F Clock Output Disable
Low
Active
6
11
PCI6 Clock Output Disable
Low
Active
5
10
PCI5 Clock Output Disable
Low
Active
4
-
--
(Reserved)
--
--
3
8
PCI4 Clock Output Disable
Low
Active
2
7
PCI3 Clock Output Disable
Low
Active
1
6
PCI2 Clock Output Disable
Low
Active
0
5
PCI1 Clock Output Disable
Low
Active
Data Byte 6
7
--
--
(Reserved)
--
--
6
--
--
(Reserved)
--
--
5
24
IOAPIC Clock Output Disable
Low
Active
4
--
--
(Reserved)
--
--
3
--
--
(Reserved)
--
--
2
--
--
(Reserved)
--
--
1
27
REF2X Clock Output Disable
Low
Active
0
27
REF2X Clock Output Disable
Low
Active
Note:
1. Bits 0 and 1 of Data Byte 6 in Table 4 must be programmed as the same value.
Default
0
0
0
0
0
0
10
0
1
0
0
0
1
0
1
1
1
1
0
1
1
1
1
0
0
1
0
0
0
1[1]
1[1]
Rev 1.0, November 28, 2006
Page 6 of 11
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