Digilent PmodBTN 410-077 User manual

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509.334.6306
www.digilentinc.com
PmodBTN™ Reference Manual
RevisedMay24,2016
ThismanualappliestothePmodBTNrev.A
DOC#: 502-077
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
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Overview
The Digilent PmodBTN gives users four momentary push-buttons for easy user inputs for the system board.
1 FunctionalDescription
The PmodBTN utilizes analog filters consisting of two resistors and a capacitor to absorb and smooth out any signal
bounces that naturally occur when pressing a button. The smoothed out voltage signal is then fed to an inverting
Schmitt-trigger which will then report a logic high voltage to the system board when a button is pressed or a logic
low voltage when the button is not being pressed.
2 InterfacingwiththePmod
The PmodBTN communicates with the host board via the GPIO protocol. For this Pmod, it will only ever send data
to the system board and ignore any signals that it might receive from the system board.
Each button is equipped with its own filter, Schmitt-trigger, and data line so that each button can be pressed
independently of each other. Users may also press the buttons simultaneously for up to 16 different input
combinations.
A pinout description and diagram of the PmodBTN are provided below:
The PmodBTN.
Four momentary pushbuttons
Debouncing filters
Inverting Schmitt Triggers
Small PCB size for flexible designs 1.2“ ×
0.8” (3.0 cm × 2.0 cm)
6-pin Pmod connector with GPIO interface
Follows Digilent Pmod Interface
Specification Type 1
Features include:

PmodBTN™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 2of 2
Pin
Signal
Description
1
BTN0
Button 0
2
BTN1
Button 1
3
BTN2
Button 2
4
BTN3
Button 3
5
GND
Power Supply Ground
6
VCC
Power Supply (3.3V/5V)
Figure 1. BTN circuit diagram.
Any external power applied to the PmodBTN must be within 1.65V and 5.5V; however, it is recommended that
Pmod is operated at 3.3V.
3 PhysicalDimensions
The pins on the pin header are spaced 100 mil apart. The PCB is 1.2 inches long on the sides parallel to the pins on
the pin header and 0.8 inches long on the sides perpendicular to the pin header.
GND
P1
P2
P3
P4
P1
P2
P3
P4
Debounce
Filter
Debounce
Filter
Debounce
Filter
Debounce
Filter
J1 Connector
Vcc
Table 1. Connector J1: Pin descriptions as labeled on the Pmod.