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Hardware Description
ARM DUI 0224F Copyright © 2003-2007 ARM Limited. All rights reserved. 3-87
3.19 User switches and LEDs
The FPGA provides a switch and LED register that enables you to read the
general-purpose pushbutton switch and the user switches (S6) and light the user LEDs
(located next to switch S6). See Figure 1-1 on page 1-3 for the location of the switches
and LEDs. Figure 3-37 shows the interface.
Note
Switch S6-1 and S6-2 are used to control the Boot Monitor. See Boot Monitor
configuration on page 2-7.
Set bits [7:0] in the SYS_LED register at
0x10000008
to illuminate LEDs 7–0. The state
of the user switches S6[8:1] is present on bits [7:0] of the SYS_SW register at
0x10000004
.
The state of the general-purpose pushbutton S3 can be read from bit 4 of the SYS_MISC
register at
0x10000060
. Setting bit 3 of SYS_MISC causes a S3 depression to generate a
PWRFAIL interrupt. The interrupt can be used to test auto-shutdown code or to awaken
the processor from sleep mode. See Miscellaneous System Control Register, SYS_MISC
on page 4-36.
Figure 3-37 Switch and LED interface