Intel
®
PXA27x Processor Developer’s Kit - User’s Guide
51
3.2.1.1
System Configuration Register (SCR)
The virtual register SCR, defined in
, contains configuration information for the main
board, Intel
®
PXA270 Processor, and expansion card. This information must be known at boot
time in order to properly configure the processor memory interface and timing registers.
Note:
The SCR is not normally available after the boot sequence has completed. If it is necessary to
access this register at any other time, follow the instructions set out in
Table 16. SCR Bit Definitions
Address (see Section 3.2.1):
system configuration word
SCR
Intel
®
PXA27x Processor Developer’s Kit
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Name
SW
AP_FLASH
EXBID
nEX
B
_
P
R
E
S
BBREV
nBB_PRES
DCREV
DCID
Reset
†
††
††
††
††
††
††
††
††
††
††
††
††
††
††
††
Bits
Name
Access
Description
15
SWAP_
FLASH
R
Status of main board switch SW2:
0 = DOT position — nCS0 connects to Intel
®
PXA270 Processor flash memory;
nCS1 to main board flash memory. The system boots from the Intel
®
PXA270
Processor bank.
1 = NO DOT position — nCS0 connects to main board flash memory; nCS1 to
Intel
®
PXA270 Processor flash memory. The system boots from the main
board bank.
14:13
EXBID
R
expansion board ID:
reserved
12
nEXB_PRES
R
expansion board Present:
0 = Expansion board is present
1 = Expansion board is absent
11:9
BBREV
R
main board revision:
0b000 —
Revision 1
0b001 —
Revision 1.1
0b010 —
Revision 2.0
0b100 —
Revision 2.1
8
nBB_PRES
R
main board present:
0 = main board is present
1 = main board is not present
7:5
DCREV
R
daughter card revision:
0b000 —
Revision 1
0b001 —
Revision 1.1
0b010 —
Reserved
4:0
DCID
R
daughter card revision:
0b00000 —
HCDDBVA0 daughter card
0b00001 —
Reserved
0b00010 —
Intel
®
PXA27x Processor DVK Daughter Card
†
Reset value depends on the position of SW2.
†† Reset values depend on the presence, revision, and type of boards used.