
CY28548
......................Document #: 001-08400 Rev ** Page 10 of 30
Control Registers
Byte 0: Control Register 0
Bit
@Pup
Name
Description
7
HW
FS_C
CPU Frequency Select Bit, set by HW
6
HW
FS_B
CPU Frequency Select Bit, set by HW
5
HW
FS_A
CPU Frequency Select Bit, set by HW
4
0
iAMT_EN
Set via SMBus or by combination of PWRDWN, CPU_STP, and PCI_STP
0 = Legacy Mode, 1 = iAMT Enabled
3
0
Reserved
2
0
SRC_Main_SEL
Select source for SRC clock
0 = SRC_MAIN = PLL1, PLL3_CFG Table applies
1 = SRC_MAIN = PLL3, PLL3_CFG Table does not apply
1
0
SATA_SEL
Select source of SATA clock
0 = SATA = SRC_MAIN, 1= SATA = PLL2
0
1
PD_Restore
Save Config. In powerdown
0 = Config. Cleared, 1 = Config. Saved
Byte 1: Control Register 1
Bit
@Pup
Name
Description
7
0
SRC0_SEL
Select for SRC0 or DOT96
0 = SRC0, 1 = DOT96
When GCLK_SEL=0, this bit is 1. When GCLK_SEL=1, this bit is 0
6
0
PLL1_SS_DC
Select for down or center SS
0 = Down spread, 1 = Center spread
5
0
PLL3_SS_DC
Select for down or center SS
0 = Down spread, 1 = Center spread
4
0
PLL3_CFB3
Bit 4:1 only applies when SRC_Main_SEL = 0
SeeTable 8: PLL3 / SE configuration table
3
0
PLL3_CFB2
2
0
PLL3_CFB1
1
PLL3_CFB0
0
1
Reserved
Byte 2: Control Register 2
Bit
@Pup
Name
Description
7
1
REF
Output enable for REF
0 = Output Disabled, 1 = Output Enabled
6
1
USB
Output enable for USB
0 = Output Disabled, 1 = Output Enabled
5
1
PCIF0
Output enable for PCIF0
0 = Output Disabled, 1 = Output Enabled
4
1
PCI4
Output enable for PCI4
0 = Output Disabled, 1 = Output Enabled
3
1
PCI3
Output enable for PCI3
0 = Output Disabled, 1 = Output Enabled
2
1
PCI2
Output enable for PCI2
0 = Output Disabled, 1 = Output Enabled
1
PCI1
Output enable for PCI1
0 = Output Disabled, 1 = Output Enabled
0
1
PCI0
Output enable for PCI0
0 = Output Disabled, 1 = Output Enabled