ARM ARM DUI 0224I 3.19 User switches and LEDs

Hardware Description

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

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