Prog_B Push-Button Switch; Ucf Location Constraints; Rotary Push-Button Switch; Locations And Labels - Xilinx Spartan-3A User Manual

Chapter 2: Switches, Buttons, and Rotary Knob

PROG_B Push-Button Switch

The PROG_B push-button switch, shown in
configuration circuitry. See

UCF Location Constraints

Figure 2-7
I/O pin assignment and the I/O standard used, and defines a pull-down resistor on each
input.

Rotary Push-Button Switch

Locations and Labels

The rotary push-button switch is located in the center of the four individual push-button
switches, as shown in
shaft encoder outputs are ROT_A and ROT_B. The center push-button switch is
ROT_CENTER.

Operation

The rotary push-button switch integrates two different functions. The switch shaft rotates
and outputs values whenever the shaft turns. The shaft can also be pressed, acting as a

push-button switch.

Push-Button Switch
Pressing the knob on the rotary/push-button switch connects the associated FPGA pin to
3.3V, as shown in
generate a logic Low.
UCF. There is no active debouncing circuitry on the push button.
28
"PROG Push-Button Switch," page
provides the UCF constraints for the four push-button switches, including the
NET "BTN_EAST" LOC = "T16" |
NET "BTN_NORTH" LOC = "T14" |
NET "BTN_SOUTH" LOC = "T15" |
NET "BTN_WEST" LOC = "U15" |
Figure 2-7: UCF Constraints for Push-Button Switches
Figure 2-5, page
Figure 2-8. Use an internal pull-down resistor within the FPGA pin to
Figure 2-11
www.xilinx.com
Figure 2-14, page
IOSTANDARD = LVTTL |
IOSTANDARD = LVTTL |
IOSTANDARD = LVTTL |
IOSTANDARD = LVTTL |
27. The switch produces three outputs. The two
shows how to specify a pull-down resistor within the
Spartan-3A/3AN Starter Kit Board User Guide
31, is part of the FPGA's
40.
PULLDOWN ;
PULLDOWN ;
PULLDOWN ;
PULLDOWN ;
UG334 (v1.0) May 28, 2007
R