Digilent 410-077P User Manual
Digilent Hardware
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w w w . d i g i l e n t i n c . c o m
Revision: 03/08/05
215 E Main Suite D | Pullman, WA 99163
(509) 334 6306 Voice and Fax
Doc: 502-077
page 1 of 1
Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.
Overview
The Digilent PmodBTN Pushbutton Module
Board (the BTN™) allows four momentary
pushbuttons to be added to any system board
using a 6-pin header connector.
Features include:
• a 6-pin header connector
• four momentary pushbutton switches
• eight protection diodes
• four Schmitt-trigger inverters
• four debouncing filters
• small form factor (1.30” x 0.80”).
Functional Description
The BTN eliminates errors caused by electrical
contacts in switches making and breaking
contact several times (“bouncing”) before
settling into position. The resulting signal is
often unusable unless it is debounced.
Each of the BTN’s four pushbutton switch
channels has an analog filter consisting of two
resistors and a capacitor. The filters absorb
and diffuse large signal bounces, presenting
smoother constantly changing signals to the
Schmitt-trigger inverters (which process switch
or logic input). The pushbutton switches can be
used individually or any of them can be used
simultaneously.
The BTN has protection diodes that prevent
damage to the inverters from overvoltage.
Resistors protect the BTN from conflicting
output voltages.
The BTN has a 6-pin header for easy
connection to a Digilent system board. For
example, some system boards like the Digilent
Pegasus board have a 6-pin header that can
connect to the BTN with a 6-pin cable.
To connect the BTN to other Digilent system
boards, a Digilent Modular Interface Board
(MIB) and a 6-pin cable are needed. The MIB
plugs into the system board, and the cable
connects the MIB to the BTN.
For more information, see
www.digilentinc.com
.
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P1
P2
P3
P4
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P2
P3
P4
Debounce
Filter
BTN Circuit Diagram
Debounce
Filter
Debounce
Filter
Debounce
Filter
J
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