Programmers Model
ARM DUI 0447J
Copyright © 2009-2014, ARM. All rights reserved.
4-11
ID052914
Non-Confidential
Configurations
See
Table 4-5
.
Attributes
See
Table 4-3 on page 4-8
.
Figure 4-4
shows the bit assignments.
Figure 4-4 SYS_SW Register bit assignments
Table 4-5
shows the bit assignments.
4.4.3
LED Register
The SYS_LED Register characteristics are:
Purpose
Controls the user LEDs on the motherboard. At reset, all LEDs are turned
off. The Boot Monitor updates the LED value.
Usage constraints
There are no usage constraints.
Configurations
Available in all configurations.
Attributes
See
Table 4-3 on page 4-8
.
31 30 29
0
Undefined
Soft user switch
8 7
SW[1]
SW[0]
28 27
nUART0CTS
nUART0DSR
Table 4-5 SYS_SW Register bit assignments
Bits
Access
Name
Reset
Description
31
Read-only
SW[1]
Indicates the value of physical
configuration switch SW[1].
See the
ARM
®
Versatile
™
Express
Configuration Technical Reference
Manual
.
30
Read-only
SW[0]
Indicates the value of physical
configuration switch SW[0].
See the
ARM
®
Versatile
™
Express
Configuration Technical Reference
Manual
.
29
Read-only
nUART0CTS
-
UART0 control signal. See the
ARM
®
Versatile
™
Express Configuration
Technical Reference Manual
.
28
Read-only
nUART0DSR
-
UART0 control signal. See the
ARM
®
Versatile
™
Express Configuration
Technical Reference Manual
[27:8]
Read-only
Undefined
-
-
[7:0]
Read-write
Soft user switch
Set to value of
USERSWITCH
in the
config.txt
file.
User applications can read these switch
settings.
If SYS_SW[0] is set, the Boot Monitor
runs its boot script.
See the
ARM
®
Versatile
™
Express Boot
Monitor Reference Manual
for more
switch settings.