Chapter 2: Switches, Buttons, And Rotary Knob; Slide Switches; Locations And Labels; Operation - Xilinx Spartan-3A User Manual

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Switches, Buttons, and Rotary Knob

Slide Switches

Locations and Labels

The Spartan-3A/3AN Starter Kit board has four slide switches, as shown in
slide switches are located in the lower right corner of the board and are labeled SW3
through SW0. Switch SW3 is the left-most switch, and SW0 is the right-most switch.

Operation

When in the UP or ON position, a switch connects the FPGA pin to 3.3V, a logic High.
When DOWN or in the OFF position, the switch connects the FPGA pin to ground, a logic
Low. The switches typically exhibit about 2 ms of mechanical bounce. There is no active
debouncing circuitry, although such circuitry could easily be added to the FPGA design
programmed on the board.

UCF Location Constraints

Figure 2-2
assignment and the I/O standard used. The PULLUP resistor is not required, but it defines
the input value when the switch is in the middle of a transition.
Spartan-3A/3AN Starter Kit Board User Guide
UG334 (v1.0) May 28, 2007
SW3 SW2
(T9) (U8)
Figure 2-1: Four Slide Switches
provides the UCF constraints for the four slide switches, including the I/O pin
www.xilinx.com
SW1 SW0
(U10) (V8)
UG330_c2_01_021507
Chapter 2
Figure 2-1. The
HIGH, '1'
LOW, '0'
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