Approved Product
C9827H
High Performance Pentium® 4 Clock Synthesizer
Serial Control Registers (Cont.)
Byte 0: CPU Clock Register
Bit
@Pup
Pin#
Description
7
0
-
Spread Spectrum Enable
0 = Spread Off, 1 = Spread On
This is a Read and Write control bit.
6
5
0
0
-
35
Reserved
3V66_1/VCH frequency Select
0 = 66M selected, 1 = 48M selected
This is a Read and Write control bit.
CPU_STP#. Reflects the current value of the external CPU_STP# (pin 53) This bit is Read Only.
4
3
Pin 53
Pin 34
44,45,48,49,
51,52
10,11,12,13,
16,17,18
Reflects the current value of the internal PCI_STP# function when read. Internally PCI_STP# is a
logical AND function of the internal SMBus register bit and the external PCI_STP# pin.
Frequency Select Bit 2. Reflects the value of SEL2 (pin 40). This bit is Read Only.
Frequency Select Bit 1. Reflects the value of SEL1 (pin 55). This bit is Read Only.
Frequency Select Bit 0. Reflects the value of SEL0 (pin 54). This bit is Read Only.
2
1
0
Pin 40
Pin 55
Pin 54
-
-
-
Byte 1: CPU Clock Register
Bit
7
6
@Pup
Pin 43
0
0
Pin#
-
-
Description
MULT0 (Pin 43) Value. This bit is Read Only.
Reserved
Controls CPU2 functionality when CPU_STP# is asserted LOW
1 = Free Running, 0 = Stopped LOW with CPU_STP# asserted LOW
This is a Read and Write control bit.
5
44,45
4
3
0
0
48,49
51,52
Controls CPU1 functionality when CPU_STP# is asserted LOW
1 = Free Running, 0 = Stopped LOW with CPU_STP# asserted LOW
This is a Read and Write control bit.
Controls CPU0 functionality when CPU_STP# is asserted LOW
1 = Free Running, 0 = Stopped LOW with CPU_STP# asserted LOW
This is a Read and Write control bit.
2
1
0
1
1
1
44,45
48,49
51,52
CPU2 Output Control, 1 = enabled, 0 = disable HIGH and CPU/2 disables LOW
This is a Read and Write control bit.
CPU1 Output Control, 1 = enabled, 0 = disable HIGH and CPU/1 disables LOW
This is a Read and Write control bit.
CPU0 Output Control, 1 = enabled, 0 = disable HIGH and CPU/0 disables LOW
This is a Read and Write control bit.
Byte 2: PCI Clock Control Register
(all bits are read and write functional)
Byte 3: PCI_F Clock and 48M Control Register
(all bits are read and write functional)
Bit
7
6
@Pup
0
1
Pin#
-
18
Description
Reserved
PCI6 Output Control
1 = enabled, 0 = forced LOW
PCI5 Output Control
1 = enabled, 0 = forced LOW
PCI4 Output Control
1 = enabled, 0 = forced LOW
PCI3 Output Control
1 = enabled, 0 = forced LOW
PCI2 Output Control
1 = enabled, 0 = forced LOW
PCI1 Output Control
1 = enabled, 0 = forced LOW
PCI0 Output Control
Bit
7
@Pup
1
Pin#
38
Description
48MDOT Output Control
1 = enabled, 0 = forced LOW
48MUSB Output Control
1 = enabled, 0 = forced LOW
PCI_STP#, control of PCI_F2.
0 = Free Running, 1 = Stopped when
PCI_STP# is LOW
PCI_STP#, control of PCI_F1.
0 = Free Running, 1 = Stopped when
PCI_STP# is LOW
PCI_STP#, control of PCI_F0.
0 = Free Running, 1 = Stopped when
PCI_STP# is LOW
PCI_F2 Output Control
1=running, 0=forced LOW
6
5
1
0
39
7
5
4
3
2
1
0
1
1
1
1
1
1
17
16
13
12
11
10
4
3
0
0
6
5
2
1
0
1
1
1
7
6
5
1 = enabled, 0 = forced LOW
PCI_F1 Output Control
1= running, 0=forced LOW
PCI_F0 Output Control
1= running, 0=forced LOW
Cypress Semiconductor Corporation
http://www.cypress.com
Document#: 38-07106 Rev. *A
12/26/2002
Page 4 of 25
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