Specifications

Programmers Model
ARM DUI 0447J Copyright © 2009-2014, ARM. All rights reserved. 4-8
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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 -