14. Register Descriptions > Register Map
150
PEB383 User Manual
July 25, 2011
Integrated Device Technology, Inc.
Confidential - NDA Required
14.3.16
PCI Miscellaneous Clock Straps Register
Register name: PCI_MISC_CLK_STRAPS
Reset value: 0x0000_0100
Register offset: 0x048
Bits
7
6
5
4
3
2
1
0
31:24
Reserved
23:16
Reserved
15:08
Reserved
CSR_SEL_
400
07:00
LEGACY
Reserved
PCGE
OP_MODE
CS_MODE
Bits
Name
Description
Type
Reset value
31:9
Reserved
Reserved
R
0
8
CSR_SEL_400
This bit programs the PLL clock:
1 = PLL Clock is 400MHz. This generates 50/50% nominal
PCI_CLKO.
0 = PLL Clock is 200MHz. This generates 33/66% nominal
PCI_CLKO.
Note: For normal operation, leave this bit in its default state.
R/W
1
7
LEGACY
Legacy Mode
When set to 1, the PEB383 operates in legacy mode (for
more information, see
).
R/W
0
6:5
Reserved
Reserved
R
0
4
PCGE
PCI clock gate enable
0b0: PCI_CLK[3:0] clock gating disabled
0b1: PCI_CLK[3:0] clock gating enabled when in D3_hot,
and in 33MHZ mode. In addition the bits “BPCCE” and
“B2B3S” in the
“PCI Power Management Control and Status
is updated to reflect this
Note
: Setting this bit to a 1 has no effect if clock rate is
higher than 33MHz.
R/W
0
3
OP_MODE
Operating Mode
0 = PEB383 provides the clock on PCI_CLKO with the
speed defined by the M66_EN signal (33/66 MHz)
1 = PEB383 provides the clock on PCI_CLKO with the
speed defined by the CS_MODE bits.
(25/33/50/60 MHz)
R/W
0