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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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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 ...
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Keypad changing ports for usage of Timers

I want to use timers of ATmega 32 ( PD4 and PD5 ) for pwm mean while i'm using Port D for keypad the available ports for me is PA7 and PC7 i want to know how can i change my code of keypad init. ...
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1answer
66 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 ...
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2answers
41 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?
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3answers
61 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 ...
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1answer
135 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 (...
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1answer
120 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 ...
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1answer
68 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 ...
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2answers
213 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 ...
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2answers
483 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 ...
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188 views

Altium keypad footprints custom pad DRC errors

I've created a rubber keypad switch footprints which is a simple contact pad design. First I used arcs and tracks to get a outline and then converted them to top copper region(two seperate regions). ...
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1answer
470 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 ...
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3k 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 ...
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2answers
3k 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 ...
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2answers
87 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 ...
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3answers
3k 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 ...
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3answers
715 views

Reducing the number of pins needed to read a 12-key keypad where the buttons are grounded?

Unfortunately, I'm not sure what the right question is; I'have a 12-key keypad. I wanted to utilise a matrix based approach, except that they all seem to be connected in such a way, that they're ...
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1answer
78 views

MULTICOMP MCAK304NBWB KEYPAD: What are the pins 8 and 9 connected to?

According to the datasheet, the 7 pins are from the 4 rows and 3 columns. What are the other 2 pins connected to ? The image shows 9 pin outs.
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307 views

Can I achieve debounce using a zener diode?

I am interfacing a 4x3 keypad with LPC1778 using GPIO pins. These pins are 5V tolerant. Can I use zener diodes in the debouncing circuit? Can I use zener diodes like this?
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1answer
689 views

Studying the PCB of a 70s calculator. What were they thinking?

I've been studying the PCB from an ELSI 8002 calculator from 1974. I'm thinking of repurposing the case for a project, though now that I've fixed it (by re soldering the battery connectors) I don't ...
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2answers
73 views

Detect position of walkers along a path using IR transceivers

I am working on a project that the position of people walking along a path needs to be known. I'm a hobbyist so I don't know what options I may have. I want to use IR sender and receivers to ...
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1answer
808 views

Calculator with MSP430 in Assembly Language

I am programming a calculator in assembly language with the MSP430g2553. I have a 4x4 membrane keypad and an 2x16 LCD. I already can display numbers in the LCD with the keypad. The issue is that the ...
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108 views

col not declared issue{Verilog}

I am having a problem here can't make this code compile. It is a 4x4 keypad scanner with a 20ms debouncer. It gives error "Error: 'col' has not been declared" Any suggestion? ...
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1answer
5k views

vhdl code interfacing keypad with fpga

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1answer
430 views

4x4 keyboard matrix not generating unique keycodes

I have a 4x4 keybord matrix fsm scanner but it generates only high keycode setting all last 4 bits to 1 and second and fourth digits to high. Is there anything wrong in my code here? ...
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1answer
2k views

How to initiate a call on a GSM module from DTMF tones

Can someone tell me if it is possible to make a call from a GSM module using only the DTMF tones that a keypad puts out? If not, can someone explain how I would make the call using only the keypad, ...
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2answers
2k views

AVR sleep interrupt with keypad

I'd like to wake up my AVR whenever any button on the keypad is pressed. I am using Keypad.h library and simple 4x4 keypad made of buttons connected straight to AVR digital pins. Keypad itself works ...
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1answer
65 views

How do I include vibration in my keypad design [closed]

I am working on a project that includes the use of a Keypad. I intend to include a beep sound with a soft vibration when a key is pressed. I am yet to figure out how to generate such vibrations. I ...
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1answer
654 views

Using the right pins for keypad

I am using msp430g2553 microcontroller and a 4x4 HC543 keypad. I am using Energia IDE. I have connected the keypad from pin 2 through 9. My code is as follows: ...
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1answer
124 views

How can i connect 9 7segments to a 3x4 keypad using only diodes making each 7segment displays only one number? [closed]

I want to make each button in the keypad to display one number using only diodes without using any decoders or ic. thanks in advance
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1answer
145 views

How does my digital watch keypad work?

I have had the same digital watch model for many years. Although they inevitably break again and again, I continue to buy the same model (A Casio 53W). I now have quite a collection of them sitting on ...
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1answer
628 views

Pinout for a 6 pin 3x4 keypad

I have this old keypad sitting around, never used it because I could never figure out the pinout for it. Anyone know how this would be wired to something such as a picaxe/arduino? Front of the keypad,...
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1answer
780 views

How to connect a 4x4 keypad without a microcontroller [duplicate]

I have the RS 331-304 4x4 keypad, and I need to connect it so that I can determine which key has been pressed without using a microcontroller. Is there a way I can connect it using logic gates? The ...
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1answer
5k views

Keypad Scanner Verilog code problem with state machine and column input

I am developing a Keypad both in hardware and Verilog using a DE2 Cyclone II board. I made a keypad using buttons (switches) that follows this schematic: The scanner works by setting the Column ...
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1answer
296 views

Pull down/pull up resistor for 5v input

I need to implement a pull-down resistor for a project, but I am unsure of what resistor to buy. My circuit deals with 5v inputs. Essentially, I am trying to make this: keypad scanner. Here is a ...
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3answers
927 views

Keypad to set a counter

Is there a way to use a standard Matrix Keypad to set a synchronous counter IC without having to use a micro controller?
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1answer
118 views

auto shift on keypad press in lcd using fujitsu F2MC-16LX MB90385 Series

We are using LCD and Keypad in our MCU and I was wondering how do i initialize my LCD so that every time there is a key press the display will automatically shift right and fill up the LCD as more ...
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1answer
292 views

PIC16F57 - problem implementing wake up signal on key stroke

I have designed a simple RC5 remote control using a PIC16F57 and the classic rows-columns scan over a 4x4 matrix keypad. The previous version of my firmware continuously scanned the keypad to find a ...
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3answers
711 views

Is there any way to interface 4x4 matrix keypad using 2 IO lines

I have two IO lines and wants to interface 4x4 matrix keypad. Using MUX ICs I need 4 IO lines. Is there any method to achieve it using 2 IOs?
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1answer
137 views

Can a keypad take any voltage?

I'm curious about keypads in regards to voltage. I have searched, and not found much related to this topic. It seems to me that keypads can take nearly any voltage so long as the voltage supplied is ...
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1answer
4k views

Lighting LED using keypad and microcontroller

So I am working with Gizduino (Arduino clone), keypad and led. What am I doing is getting the value of keypressed and then light up the led according to the value (eg., when I pressed 2 on the keypad ...
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3answers
16k views

4x4 keypad to Microcontroller

I have 8pin 4x4 keyapd, and i want to connect it to my microcontroller, I've search over the net but i can't see its pin configuration. I have a problem connecting it because of that can someone help ...
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1answer
5k views

Arduino pin descriptions

Hello, actually I am very new in electronics. Im using this as a reference in connecting lcd and 4x4 keypad in my my controller ( an arduino clone) Gizduino ATMEGA644 but I'm having a problem because ...
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1answer
137 views

Is this circuit a viable implementation? [duplicate]

Following on from an earlier question where the implementation was flawed, can anyone advise if the below is a viable implementation of a circuit to handle a matrix keypad? The idea is that one ...
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3answers
6k views

Interfacing Keypad to PIC16F877A

I am interfacing a 3X4 keypad to PIC16f877a uC on PORTD as: In the first half of the C program I have set first four pins to Input (From LSB-RD0) and others to Output and store the value in a ...
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1answer
872 views

Seeking 4x3 keypad for Atmel UC3 microprocessor

I was doing a combined project with a friend, with me on s/w and him on h/w. After a year of coding on my part & not much activity on his, he announced that he is "too busy" to continue. That ...
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2answers
3k views

MPS430 Launchpad Keypad

I tried to use my MSP430G2553 launchpad with a keypad using http://www.pjrc.com/teensy/td_libs_Keypad.html http://bildr.org/2011/05/arduino-keypad/ http://www.instructables.com/id/Using-the-sparkfun-...
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2answers
472 views

Calculator with phone keypad question [closed]

I am not an electronic person and found this site in a my quest for the perfect calculator. I use both a phone and calculator for calculations and find the back and forth to cause me to make errors ...
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2answers
936 views

Arduino 3 digit LCD calculator

We would like to build a calculator using Arduino which uses 3 digit LCD and a keypad similar to digital phones. (# for plus , * for minus) Which components and way is good enough to not to run out of ...
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3answers
3k views

Which schematic is better for keypad connection to an MCU?

I have this three keypad connection sketches, all of which i've seen in various application, and some i've also used, but i want to know if there is any advantage of one over the other. The keypad ...