CY28346-2
Rev 1.0, November 20, 2006 Page 4 of 19
Byte 0: CPU Clock Register
Bit @Pup Name Description
7 0 Spread Spectrum Enable, 0 = Spread Off, 1 = Spread On. This is a Read and Write control bit.
60
CPU clock Power-down Mode Select.
0 = Drive CPUT(0:2) to 4 or 6 IREF and drive CPUC(0:2) to low when PD# is asserted LOW.
1 = Three-state all CPU outputs. This is only applicable when PD# is LOW. It is not applicable to
CPU_STP#.
503V66_1/VCH 3V66_1/VCH frequency Select, 0 = 66M selected, 1 = 48M selected
This is a Read and Write control bit.
4 Pin 53 CPUT,CPUC CPU_STP#. Reflects the current value of the external CPU_STP# (pin 53) This bit is Read-only.
3Pin 34 PCI 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.
2 Pin 40 Frequency Select Bit 2. Reflects the value of SEL2 (pin 40). This bit is Read-only.
1 Pin 55 Frequency Select Bit 1. Reflects the value of SEL1 (pin 55). This bit is Read-only.
0 Pin 54 Frequency Select Bit 0. Reflects the value of SEL0 (pin 54). This bit is Read-only.
Byte 1: CPU Clock Register
Bit @Pup Name Description
7 Pin 43 MULT0 MULT0 (Pin 43) Value. This bit is Read-only.
6 0 CPU_STP#
Controls functionality of CPUT/C(0:2) outputs when CPU_STP# is asserted. 0 = Drive CPUT(0:2) to
4 or 6 IREF and drive CPUC(0:2) to low when CPU_STP# asserted LOW. 1 = Three-state all CPU
outputs. This bit will override Byte0, Bit6 such that even if it is a 0, when PD# goes low the CPU outputs
will be three-stated.
50 CPUT2
CPUC2
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.
40 CPUT1
CPUC1
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.
30 CPUT0
CPUC0
Controls CPUT0 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.
21 CPUT2
CPUC2
CPUT/C2 Output Control, 1 = enabled, 0 = disable HIGH and CPUC2 disables LOW
This is a Read and Write control bit.
11 CPUT1
CPUC1
CPUT/C1 Output Control, 1 = enabled, 0 = disable HIGH and CPUC1 disables LOW
This is a Read and Write control bit.
01 CPUT0
CPUC0
CPUT/C0 Output Control, 1 = enabled, 0 = disable HIGH and CPUC0 disables LOW
This is a Read and Write control bit.
Byte 2: PCI Clock Control Register (all bits are read and write functional)
Bit @Pup Name Description
7 0 REF REF Output Control. 0 = high strength, 1 = low strength
6 1 PCI6 PCI6 Output Control. 1 = enabled, 0 = forced LOW
5 1 PCI5 PCI5 Output Control. 1 = enabled, 0 = forced LOW
4 1 PCI4 PCI4 Output Control. 1 = enabled, 0 = forced LOW
3 1 PCI3 PCI3 Output Control. 1 = enabled, 0 = forced LOW
2 1 PCI2 PCI2 Output Control. 1 = enabled, 0 = forced LOW
1 1 PCI1 PCI1 Output Control. 1 = enabled, 0 = forced LOW
0 1 PCI0 PCI0 Output Control. 1 = enabled, 0 = forced LOW