Table 4-8. Clock Generator Configuration - AMD Geode SC3200 Data Book

General Configuration Block
4.5.7 Clock Registers
Table 4-8 describes the registers of the clock generator and PLL.
Bit Description
Offset 10h
This register holds the maximum core clock multiplier value. The maximum clock frequency allowed by the core, is the Fast-PCI clock
multiplied by this value.
7:4 Reserved.
3:0 MCM (Maximum Clock Multiplier). This 4-bit value is the maximum multiplier value allowed for the core clock generator. It
is derived from strap pins CLKSEL[3:0] based on the multiplier value in Table 4-7 on page 83.
Offset 11h
Offset 12h
This register controls operation of the PLLs.
7 Reserved.
6 EXPCID (Disable External PCI Clock).
0: External PCI clock is enabled.
1: External PCI clock is disabled.
5 GPD (Disable Graphic Pixel Reference Clock).
0: PLL2 input clock is enabled.
1: PLL2 input clock is disabled.
4 Reserved.
3 PLL3SD (Shut Down PLL3). AC97 codec clock.
0: PLL3 is enabled.
1: PLL3 is shutdown.
2 FM1SD (Shut Down PLL4).
0: PLL4 is enabled.
1: PLL4 is shutdown, unless internal Fast-PCI clock is strapped to 48 MHz.
1 C48MD (Disable SuperI/O and USB Clock).
0: USB and SuperI/O clock is enabled.
1: USB and SuperI/O clock is disabled.
0 Reserved. Write as read.
Offset 13h-17h
Offset 18h-1Bh
31:24 MFFC (MFF Counter Value).
Fvco = OSCCLK * MFBC / (MFFC * MOC)
OSCCLK = 27 MHz
23:19 Reserved. Write as read.
18:8 MFBC (MFB Counter Value).
Fvco = OSCCLK * MFBC / (MFFC * MOC)
OSCCLK = 27 MHz
Note: Bits 18, 9, and 8 cannot be changed. Bit 18 is always a 1; bits 9 and 8 are always 0.
7 Reserved. Write as read.
6 Reserved. Must be set to 0.
5:0 MOC (MO Counter Value).
Fvco = OSCCLK * MFBC / (MFFC * MOC)
OSCCLK = 27 MHz
AMD Geode™ SC3200 Processor Data Book

Table 4-8. Clock Generator Configuration

Maximum Core Clock Multiplier Register - MCCM (RO)
Reserved - RSVD
PLL Power Control Register - PPCR (R/W)
Reserved - RSVD
PLL3 Configuration Register - PLL3C (R/W)
32581C
Reset Value: Strapped Value
Reset Value: 2Fh
Reset Value: E1040005h
85