UM1585
Strapping options
Doc ID 023872 Rev 1
10 Strapping
options
General purpose I/Os are present on the board. They are connected to DIP switches to
allow the user to select/deselect them.
Immediately after reset phase, the SPEAr can be configured by means of the GPIO_A0 ...
A3 strapping options.
2 µs after reset, pins can be used with GPIO features.
Note:
Important: To use pins as input, the external pin driver must be in tri-state for the duration of
the reset phase plus 2 µs.
Note:
When DIP switch SWx-x is in the ON position, the bit value is 0. When the DIP switch is in
the OFF position, the bit value is 1.
Table 18.
Switch 3 (SW3) configuration
Pin
Description (default settings)
1
GPIO_A0 (OFF) (See
Table 20: Software boot options
for description)
2
GPIO_A1 (ON) (See
Table 20: Software boot options
for description)
3
GPIO_A2 (ON) (See
Table 20: Software boot options
for description)
4
GPIO_A3 (ON) (See
Table 20: Software boot options
for description)
8
Not used
Table 19.
Switch 4 (SW4) configuration
Pin
Description (default settings)
1
NAND Flash interface voltage (OFF)
OFF = 3.3 volt
ON = 1.8 volt
2
GMII interface 2.5 V (OFF)
OFF = 3.3 V
ON = 2.5 V
3
PCI level (to allow a PCI implementation in the SPEAr13x RAS) (OFF)
OFF = Normal level
ON = PCI level for PL_GPIO[86÷99] [6÷53]
4
Not used
Table 20.
Software boot options
Boot Type
SW3-4
GPIO_A3
SW3-3
GPIO_A2
SW3-2
GPIO_A1
SW3-1
GPIO_A0
Bypass internal bootROM and jump to code in serial
NOR Flash (SMI interface)
0
0
0
0
Boot from external serial NOR Flash (SMI).If the code
not valid, boot from USB is forced.
0
0
0
1