Programmers Model
ARM DUI 0447J
Copyright © 2009-2014, ARM. All rights reserved.
4-8
ID052914
Non-Confidential
4.3
Register summary
This section describes the system registers on the motherboard.
Note
All registers are 32 bits wide and do not support byte writes. Write operations must be
word-wide and bits marked as
reserved
must be preserved using read-modify-write.
The following information applies to the Motherboard Express uATX registers:
•
If your daughterboard uses the ARM Legacy memory map, the system register addresses
are offsets from the SMB CS7 base address and this depends on the mapping in the
daughterboard. See the Technical Reference Manual for your daughterboard.
•
If your daughterboard uses the ARM
Cortex-A Series
memory map, the system register
addresses are offsets from the SMB CS3 base address and this depends on the mapping in
the daughterboard. See the Technical Reference Manual for your daughterboard.
•
Do not attempt to access reserved or unused address locations. Attempting to access these
locations can result in Unpredictable behavior.
Table 4-3
shows the registers in offset order from the base memory address.
Table 4-3 Register map for status and system registers
Offset
Value
Register
Type
Reset Description
0x0000
SYS_ID
RO/RW
a
0xX190XXXX
b
System Identifier. See
ID Register
on page 4-10
.
0x0004
SYS_SW
RO/RW
a
0xX00000XX
b
Bits [7:0] are the soft user switches. See
User Switch Register
on
page 4-10
.
0x0008
SYS_LED
RO/RW
a
0x000000XX
b
Bits [7:0] map to user LEDs. See
LED Register
on page 4-11
.
0x000C
–
0x0020
Reserved
RO
0x00000000
-
0x0024
SYS_100HZ
RO
0xXXXXXXXX
b
100Hz counter. See
100Hz Counter Register
on page 4-12
.
0x0030
SYS_FLAGS
RO
0x00000000
See
Flag Registers
on page 4-12
.
0x0030
SYS_FLAGSSET
WO
-
See
Flag Registers
on page 4-12
.
0x0034
SYS_FLAGSCLR
WO
-
See
Flag Registers
on page 4-12
.
0x0038
SYS_NVFLAGS
RO
0x00000000
See
Flag Registers
on page 4-12
.
0x0038
SYS_NVFLAGSSET
WO
-
See
Flag Registers
on page 4-12
.
0x003C
SYS_NVFLAGSCLR
WO
-
See
Flag Registers
on page 4-12
.
0x0040
–
0x0044
Reserved
RO
0x00000000
-
0x0048
SYS_MCI
RO
0x00000002
MCI status and control register. See
MCI Register
on page 4-13
.
0x004C
SYS_FLASH
RW
0x00000000
Controls write protection of flash devices. See
Flash Control
Register
on page 4-14
.
0x0050
–
0x0054
Reserved
RO
0x00000000
-