Motherboard Express µATX Technical Reference ManualV2M-P1
Home > Programmers Model > Register descriptions > User Switch Register

4.4.2. User Switch Register

The SYS_SW Register characteristics are:

Purpose

Reads the USERSWITCH entry in the config.txt file. A value of 1 indicates that the switch is on.

Usage constraints

See Table 4.5.

Configurations

See Table 4.5.

Attributes

See Table 4.3.

Figure 4.4 shows the bit assignments.

Figure 4.4. SYS_SW Register bit assignments

To view this graphic, your browser must support the SVG format. Either install a browser with native support, or install an appropriate plugin such as Adobe SVG Viewer.


Table 4.5 shows the bit assignments.

Table 4.5. SYS_SW Register bit assignments

Bits

Access

NameResetDescription
31Read-onlySW[1]Indicates the value of physical configuration switch SW[1].See Versatile Express Configuration Technical Reference Manual.
30Read-onlySW[0]Indicates the value of physical configuration switch SW[0].See Versatile Express Configuration Technical Reference Manual.
29Read-onlynUART0CTS-UART0 control signal. See Versatile Express Configuration Technical Reference Manual.
28Read-onlynUART0DSR-UART0 control signal. See Versatile Express Configuration Technical Reference Manual.
[27:8]Read-onlyUndefined--
[7:0]Read-writeSoft user switchSet 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 Versatile Express Boot Monitor Reference Manual for more switch settings.


Copyright © 2009-2013, ARM. All rights reserved.ARM DUI 0447H
Non-ConfidentialID040613
PDF file icon  PDF version
Home > Programmers Model > Register descriptions > User Switch Register