Push-Button Switches; Locations And Labels; Operation - Xilinx Spartan-3E User Manual

Chapter 2: Switches, Buttons, and Knob

Push-Button Switches

Locations and Labels

The Spartan-3E Starter Kit board has four momentary-contact push-button switches,
shown in
are labeled BTN_NORTH, BTN_EAST, BTN_SOUTH, and BTN_WEST. The FPGA pins
that connect to the push buttons appear in parentheses in
UCF appears in
BTN_WEST

Operation

Pressing a push button connects the associated FPGA pin to 3.3V, as shown in
Use an internal pull-down resistor within the FPGA pin to generate a logic Low when the
button is not pressed.
UCF. There is no active debouncing circuitry on the push button.
16
NET "SW<0>" LOC = "L13" |
NET "SW<1>" LOC = "L14" |
NET "SW<2>" LOC = "H18" |
NET "SW<3>" LOC = "N17" |
Figure 2-2: UCF Constraints for Slide Switches
Figure 2-3. The push buttons are located in the lower left corner of the board and
Figure 2-5.
(D18)
Notes:
1. All BTN_* push-button inputs require an internal pull-down resistor.
2. BTN_SOUTH is also used as a soft reset in some FPGA applications.
Figure 2-3: Four Push-Button Switches Surround Rotary Push-Button Switch
Figure 2-5
www.xilinx.com
IOSTANDARD = LVTTL |
IOSTANDARD = LVTTL |
IOSTANDARD = LVTTL |
IOSTANDARD = LVTTL |
Rotary Push Button Switch
ROT_A: (K18)
BTN_NORTH
ROT_B: (G18)
(V4)
ROT_CENTER: (V16)
BTN_SOUTH
(K17)
shows how to specify a pull-down resistor within the
Spartan-3E Starter Kit Board User Guide
PULLUP ;
PULLUP ;
PULLUP ;
PULLUP ;
Figure 2-3 and the associated
Requires an internal pull-up
Requires an internal pull-up
Requires an internal pull-down
BTN_EAST
(H13)
UG230_c2_02_021206
Figure
UG230 (v1.0) March 9, 2006
R
2-4.