
58
AMD Geode SC2200 Processor Data Book
Revision 5.1
3.2
Strap Options
Several balls are read at power-up that set up the state of
the SC2200. These balls are typically multiplexed with
other functions that are outputs after the power-up
sequence is complete. The SC2200 must read the state of
the balls at power-up and the internal PU or PD resistors
do not guarantee the correct state will be read. Therefore, it
is required that an external PU or PD resistor with a value
of 1.5 K
value of the resistor is important to ensure that the proper
state is read during the power-up sequence. If the ball is
not read correctly at power-up, the SC2200 may default to
a state that causes it to function improperly, possibly result-
ing in application failure.
Table 3-6. Strap Options
Strap
Option
Muxed With
Ball No.
Nominal
Internal
PU or PD
External PU/PD Strap Settings
Register References
EBGA
TEPBGA
Strap = 0 (PD)
Strap = 1 (PU)
CLKSEL0
RD#
F3
B8
PD100
CLKSEL strap options.
GCB+I/O Offset 1Eh[9:8] (aka
CCFC register bits [9:8]) (RO):
Value programmed at reset by
CLKSEL[1:0].
GCB+I/O Offset 10h[3:0] (aka
MCCM register bits [3:0]) (RO):
Value programmed at reset by
CLKSEL[3:0].
GCB+I/O Offset 1Eh[3:0] (aka
CCFC register bits [3:0]) (R/W,
but write not recommended):
Value programmed at reset by
CLKSEL[3:0].
Note: Values for GCB+I/O Off-
set 10h[3:0] and 1Eh[3:0] are not
the same.
CLKSEL1
SOUT1
B27
AF3
PD100
CLKSEL2
SOUT2
AK3
D29
PD100
CLKSEL3
SYNC
AL13
P30
PD100
BOOT16
ROMCS#
G4
C8
PD100
Enable boot
from 8-bit ROM
Enable boot
from 16-bit
ROM
GCB+I/O Offset 34h[3] (aka MCR
register bit 3) (RO): Reads back
strap setting.
GCB+I/O Offset 34h[14] (R/W):
Used to allow the ROMCS# width
to be changed under program
control.
TFT_PRSNT
SDATA_OU
T
AK13
P29
PD100
TFT not muxed
onto Parallel
Port
TFT muxed
onto Parallel
Port
GCB+I/O Offset 30h[23] (aka
PMR register bit 23) (R/W):
Reads back strap setting.
LPC_ROM
PCICLK1
E4
D6
PD100
Disable boot
from ROM on
LPC bus
Enable boot
from ROM on
LPC bus
F0BAR1+I/O Offset 10h[15] (R/
W): Reads back strap setting and
allows LPC ROM to be changed
under program control.
FPCI_MON
PCICLK0
D3
A4
PD100
Disable Fast-
PCI, INTR_O,
and SMI_O
monitoring sig-
nals.
Enable Fast-
PCI, INTR_O,
and SMI_O
monitoring sig-
nals. (Useful
during debug.)
GCB+I/O Offset 34h[30] (aka
MCR register bit 30) (RO): Reads
back strap setting.
Note: For normal operation, strap
this signal low using a 1.5 K
resistor.
DID0
GNT0#
D4
C5
PD100
Defines the system-level chip ID.
GCB+I/O Offset 34h[31,29] (aka
MCR register bits 31 and 29)
(RO): Reads back strap setting.
Note: GNT0# must have a PU
resistor of 1.5 K
and GNT1#
must have a PD resistor of 1.5
K
.
DID1
GNT1#
D2
C6
PD100
Note:
Accuracy of internal PU/PD resistors: 80K to 250K.
Location of the GCB (General Configuration Block) cannot be determined by software. See the AMD Geode SC2200 Proces-
sor Specification Update document.