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Questions tagged [keypad]

Keypads are typically small 3x4 or 4x4 membrane button matrixes, used for phones or other devices needing numerical input. Similar to keyboards.

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Rigid 4x4 keypad decoder - voltage drop

I am trying to implement a keypad decoder: it has 8 digital outputs, 4 that indicate the row of the pressed button, and the other 4 associated with columns. There are green LEDs that serve as a visual ...
lachoprime's user avatar
1 vote
4 answers
180 views

What is the fewest number of GPIOs to read 5 push-buttons?

This answer gives a good explanation of how to use a keypad matrix to minimize GPIO usage by scanning rows and columns to find a button press when an interrupt triggers. This scales very nicely for ...
KJ7LNW's user avatar
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How to place light guide film cuts as part of layer PCB

How can I go about doing something like this in fusion/ eagle? https://www.pannam.com/wp-content/uploads/2017/08/Implementing-LGF.pdf and https://www.snaptron.com/2021/03/how-to-place-metal-dome-...
Wes Ellgass's user avatar
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1 answer
47 views

What is it needed to repair the pressure pads of an electric piano keyboard? [closed]

I don’t know if this is the right place to ask, but this is important to me, so i hope you understand. I have an electric piano keyboard (Korg Kross I). It is supposed to detect automatically the ...
Simón Flavio Ibañez's user avatar
0 votes
1 answer
193 views

Emulate key presses with Arduino

I have a robot mower that I'd like to make "smart" by using an Arduino compatible board to mimic key presses via the Blynk app. The control board of the mower is based on a [TM1668 chip] (...
user2879284's user avatar
0 votes
2 answers
323 views

How to connect a 4x4 matrix keypad to one analog pin?

I watched this video on YouTube, the video's creator shows how we can connect a keypad to just one single analog pin of Arduino UNO instead of using (number of columns + number of rows) pins by using ...
M-125's user avatar
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72 views

The receiver sends correct but too much information to the keyboard with STM32 nRF24

I have a problem with keyboard hid. I did remote control with STM32 transceiver nRF24. My problems that receiver true receiving incoming data but too much text. Problems that: ...
Sk16's user avatar
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2 answers
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Hardware wiring problem with keypad scan

I am trying to write keypad (4*4) scan VHDL code for my DE10-lite board. In order to avoid floating signal for the input, I need pull up resistors. There is an example I found from YouTube However, ...
kile's user avatar
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1 vote
1 answer
106 views

MSP 430G2553 Keypad Error

I am trying to use 4x3 Keypad with MSP430G2553. I used code from electronicwings site ...
armancj2's user avatar
0 votes
1 answer
136 views

Can I replace this keypad with an Arduino / Raspberry Pi GPIO

I need to replace the keypad from this board with a Raspberry Pi or Arduino so I can control programmatically what keys are sent to the board (so I can automate keypad press, without having the ...
Owow's user avatar
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4 answers
101 views

Is it possible to get a tactile switch with more than two rails?

Making a button-based input device for my Raspberry Pi. When a pin is pulled to ground it registers a false, so: "if pin 1 = false output = 1". The problem is I need 30 buttons and I only ...
Nareik Seivad's user avatar
0 votes
1 answer
500 views

How to use ESP32's input-only pins with keypad library

I am trying to use a 1x4 keypad with an ESP32. I am using this keypad and this ESP32 (30 pins); I am also using this keypad library. I have only pins 14, 15, 34, 36 (VN), and 39 (VP) free on the ESP32,...
mehmet's user avatar
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0 answers
233 views

Problem with TTP229-BSF using Arduino Uno

I'm trying to use a 16-channel capacitive touch sensor named TTP229-BSF with an Arduino Uno. I use the following code it works correctly when i touch directly but when i place two 4 mm plexiglass pads ...
salar1991's user avatar
1 vote
2 answers
94 views

strange behavior of 3x4 keypad [closed]

hi i tried to use the keypad.h library for sending a pressed key to serial port of esp32 by Arduino platform but it didn't work and it only detected rows. so i tried to write a function for running ...
salar1991's user avatar
3 votes
1 answer
147 views

Replacing a keypad on DYMO LetraTag

I'm rebuilding my label printer to become an Internet service using an ESP8266. It's a fun project, never mind the usefulness. The keypad will be removed and instead my MCU emulates keypresses. The ...
mikabytes's user avatar
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2 votes
1 answer
101 views

Theory of operation of MM74C922N

I have been studying the datasheet of the MM74C922N , a 4x4 matrix keypad, but I cannot seem to understand how it works under the 'Theory of Operation'. I know it outputs a 4-bit binary code depending ...
BeatriceUK's user avatar
4 votes
2 answers
672 views

4x4 matrix keypad interface with microcontroller

I am extremely new to microcontrollers and PIC programming. I need help in understanding how a 4x4 matrix keypad works. I know the 8 pins are used to determine which of the keys are pressed by the ...
Fiidisks's user avatar
0 votes
2 answers
468 views

Keypad interfacing on microcontroller

I am extremely new to dealing with microcontrollers and programming in general. The picture below is a circuit board using a PIC18F4520 microcontroller. As of now, I am focused on the 4x4 matrix ...
BeatriceUK's user avatar
2 votes
2 answers
130 views

Membrane switch - 39 switches - 11 inputs and only 6 outputs to processor

I have reverse engineered a membrane keypad that connects to a microprocessor. I have no info on the keypad but it has 39 switches. The output of the keypad is an 11 way ribbon cable. This goes to a ...
mike james's user avatar
0 votes
2 answers
111 views

Make a faux call on old 1950s touch tone phone [closed]

I have a 1950s ice cream shop and just bought a vintage touch tone phone. It works if I connect it to a phone line but I won't be doing this. What I really want to do is pre-record messages that will ...
Joey Martin's user avatar
0 votes
1 answer
136 views

Error in LCD while interfacing with ATmega 32

I am trying to interface a normal keypad and LCD .where for example if i press '1' in keypad it will show 'one' in the display . if i press '=' it will show 'EQUAL' in Display . i developed below code ...
bighero666's user avatar
0 votes
0 answers
36 views

Touch pad Document

I tear down one touch pad and wonder what technology they used. I am sharing picture of it. Any one know what is used for touch sense ? (my guess is capacitive). I am planning to design one by myself. ...
Dharmik Prajapati's user avatar
0 votes
1 answer
456 views

Combining interrupts and debouncing on a keypad

I would like to interrupt a program when a key is pressed on a keypad, and figure out which key has been pressed. I do not care much for ghosting effects, this is supposed to be operated with one ...
user42875's user avatar
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1 vote
1 answer
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Setting Pulldown on the PMOD Pins (Nexys A7)

Ive created a keypad scanning project with Verilog. The waveform works great! But it did not work in practice. Through troubleshooting I found that it will work if I add external pulldown resistors to ...
dka13's user avatar
  • 165
0 votes
1 answer
504 views

Problem with Keypad exercise on STM32 (Nucleo-F103RB)

I try to learn STM32 MCU programming and at the beginning I'd like to mark, that't I'm totally begginer in it, so please forgive me some mistakes (also language mistakes). So I'm using STM32F103RBT6 (...
ABC's user avatar
  • 61
2 votes
0 answers
101 views

Using an MCP23008 IC with a 4X4 matrix keypad on a Raspberry Pi [closed]

I want to be able to free up the native GPIO pins on my Raspberry Pi Zero. I know the MCP23008 gives me 8 extra pins, but I can't seem to find any resources on using the additional pins with a 4X4 ...
Pekkle Juice's user avatar
0 votes
2 answers
103 views

Raspberry Pi sometimes detects wrong keypad number

I am using a 3 x 4 Sparkfun keypad connected to a Raspberry Pi. The issue I am facing is that 40% of the time wrong keypad numbers get detected after pressing the button. For example, when I press &...
Nitesh Singh's user avatar
1 vote
0 answers
722 views

Resistor Keyboard Vs Matrix Keyboard

I'm part way through my prototye macro keyboard which currently consists of 4 keypads with 16 keys on each - so 64 keys in total. The method I'm using is the 3 wire, resistor based one.R1,R2,R3 and ...
Fuzzy's user avatar
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1 vote
2 answers
125 views

Keypad schematic - is it correct?

What do you think of this schematic for my Arduino keypad? Are the diodes pointing the right way? I will make col1 "high" and then check pins ...
herrybertpotter's user avatar
-1 votes
1 answer
70 views

Why are my keypad pins more than total number of columns and rows?

I have newly bought the following keypad with 4 rows and 3 columns from a not well-recognized shop. But I am wondering, why it has 10 pins in spite of 7 pins (total number of rows and columns). ...
Bornak's user avatar
  • 85
-1 votes
2 answers
151 views

Interfacing 4*4 keypad avr-gcc [duplicate]

I have this function for a 4x4 keypad: ...
Danial's user avatar
  • 223
3 votes
2 answers
370 views

avr-gcc keypad interfacing code problem

I have this function to read key press from a 4x3 key-board: ...
Danial's user avatar
  • 223
0 votes
2 answers
1k views

NVG compatibility LED Lights

For an avionics application I need to make a keypanel which has NVG compatible LED lights behind its keys. I am trying to understand how does the NVG compatibility (Night vision Goggles) relates to ...
alt-rose's user avatar
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0 votes
2 answers
127 views

keypad debouncer configuration RC Value

I have keypad with for buttons and common signal connected to ground.. I noticed two configuration for debouncing as shown bellow.. Question: - Will the both configuration work correctly? when ...
user192043's user avatar
0 votes
1 answer
536 views

Keypad saved shifting display using Verilog

I'm designing a number exchange module, and so far I've been able to make it display on Seven Segment Display (S-S-D), like if I press 0 it shows 0... etc. I'm using 2 sets of 4-bits S-S-D (Common ...
EEcmyang's user avatar
0 votes
1 answer
1k views

How do you make crossing wires not connect in EAGLE? [closed]

I am brand new to PCB designing (started yesterday) and am doing it as a fun little side project. My goal is to produce a working PCB that has a very basic function. My problem is this: I have no ...
Mine Thing's user avatar
2 votes
3 answers
5k views

Clean/repair/replace the carbon pill of a rubber keypad

I have several devices (calculators, remote controllers, …) with rubber keypads where some keys are dysfunctioning. As I understand it, this is because of the carbon pill since things work fine if I ...
user2233709's user avatar
  • 1,745
-3 votes
1 answer
146 views

how rubber keypad works [closed]

Press on the keyboard, how does he connect the circuit of this key? Two thin films, coated with conductive rubber circuit, with a thin film in the middle, with holes, used to isolate two thin films ...
Hardy Ho's user avatar
0 votes
2 answers
209 views

how to mount a flat keypad on a panel

Flat Keypad or Membrane Keypads are cheap and beautiful Keyboad that can be used in systems. but the question is how can they be mounted in a box or panel?
david's user avatar
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0 votes
3 answers
193 views

I designed a touch PCB keypad what can I do for silking and covering

I want to design a custom keypad for my board. I put my board in a Plastic box 15cm x 19cm and the box has a simple box door. I want to put a keypad and a 2x16 character LCD in this door to control ...
david's user avatar
  • 103
0 votes
1 answer
263 views

8051 program not processing keypad matrix correctly

I made myself a small PCB (measuring about 6cm by 5cm). This is what is supposed to happen: Upon power-up, the LED goes red to indicate that the unit is ready for input. I then press any key down (...
Mike -- No longer here's user avatar
1 vote
2 answers
955 views

Silicone rubber keypad PCB design

I have a question regarding PCB design and rubber keypad contacts. I did this circuit for prototyping a piano keybed but some contacts seem to be unstable: when pressed it switches from 0 to 1 ...
Olivier's user avatar
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2 votes
1 answer
113 views

Learning the Art of Electronics - keypad schematic

The image below is an extract from the schematic for the keypad referred to on page 620 of LAoE. What does the symbol connecting switch S4 to pin 11 of U7 and connecting pins 6 and 11 of U7 mean in ...
David1's user avatar
  • 137
1 vote
2 answers
359 views

Learning the Art of Electronics - keypad

Has anyone found ordering information or the schematic referred to on Page 620 of Learning the Art of Electronics? Page 620 of LAoE says, "The keypad is not a standard commercial part. See Appendix E ...
David1's user avatar
  • 137
0 votes
2 answers
1k views

Connect 4x4 keypad to esp8266 I2C

I want to connect 4x4 keypad to nodemcu, but some of the pins on board are already in use. For LCD I have used I2C backpack, and have an extra lying around. Can it be used to connect keypad to nodemcu ...
kryptxy's user avatar
0 votes
1 answer
1k views

Wake up ESP-32 using matrix keypad

I want to realize a wireless keypad using ESP-32 and a matrix 4x3 keypad, connected via Bluetooth Low Energy to a master unit. I want to use deep sleep mode of ESP-32 when the keypad is not used but I ...
Alessandro Dionisi's user avatar
11 votes
3 answers
4k views

How does the telephone's keypad work?

I disassembled some old telephone and mobile phone. Every keypad is different, and yet, all of them have those "spirals" (see the image below) under the button or something similar. What I don't ...
Tripola's user avatar
  • 733
1 vote
2 answers
12k views

Weak key fob signal

I have a VW Golf 5 from 2004. I have bought it about 4 years a go. I have 2 pairs of keys. With the first one, I could never open the car remotely. The second one worked quite well but its range ...
Łukasz Przeniosło's user avatar
2 votes
2 answers
213 views

Would it be possible to replace/wire the buttons on a keypad with buttons from this old phone?

Sorry I know the title's a little rough, but hopefully some pictures will help I have this keypad Here it is the front panel removed (note that each metal node is a button in itself, you can press ...
A O's user avatar
  • 227
10 votes
3 answers
5k views

Silicone Keypad Design Problems

My device uses a silicone keypad to detect a key press rather than a physical button. After setting up, it works smoothly, even without applying much pressure to the keypad. However, after a while ...
Paul A.'s user avatar
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