Questions tagged [keyboard]

A Keyboard is an input device typically made of a large array of switches. The interface could be the raw matrix, or an industry standard protocol like PS/2 or USB.

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57 views

Keyboard switch removal problems

I recently put together a keyboard and had an issue with a couple switches so I decided to re-solder. I resoldered 2 and that fixed the issues but for this last one I started smelling something ...
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80 views

Schematic suggestions for a beginner

(From a complete beginner) I've had this idea to build my own keyboard from scratch for a while, and I finally got the time (and motivation) this winter break to go ahead and try it for myself. After ...
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Rubber insides and circuit transparent sheets of USB keyboard don't work outside of plastic case

I have very little knowledge of electronics and circuits, so I apologize in advance if the question is dumb. I couldn't find answer anywhere. I am trying to remove plastic part of my keyboard and ...
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31 views

How to connect rows and columns in a keyboard matrix

I want to build a keyboard from scratch, so I started by designing the schematics. I have found several ones on the web in which the switch - diode direction is connected from row to column, and ...
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45 views

Building a keyboard matrix

I want to build a 7 Rows x 15 Columns keyboard from scratch, thus I have started from the theoretical design of the matrix. The classic way should be to assign directly the Rows and Columns to (7+15) ...
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38 views

Keyboard matrix and its microcontroller type

I'm planning to make a custom 108 keys keyboard from scratch. Unfortunately, I'm currently stuck in a circuitry situation. Is there a lean matrix that I can go with for this and what kind of ...
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52 views

Membrane keyboards circuit

I study the different keyboard technologies and I have noticed that on membrane keyboards there are no diodes to prevent ghosting. From what I understand: The switch are placed in such a way that ...
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3answers
104 views

Rapidly driving a keyboard signal

My goal is to build something that simulates rapidity (50 to 1k Hz) pressing a key on a USB keyboard. My first inclination was drive a transistor from a 555 timer with the two keyboard matrix pins on ...
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143 views

Arduino emulating a keyboard that has a demultiplexer

I have a old typewriter which I want to automate with an Arduino. The way I am trying to do it is to replace its keyboard with the Arduino and make the Arduino emulate the keyboard i/o. The keyboard ...
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129 views

Messages sent when keyboard key is pressed [closed]

When pressing keys on a keyboard what messages are sent to a PC? Is it OK to send this message using a micro controller (through USB cable)? This is the protocol format i got from website. how to ...
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95 views

Malfunctioning atmega32u4 split keyboard — help diagnose

I purchased this split keyboard kit called a gergo and assembled it myself. The board properly registered via usb so I flashed it with qmk which has very good support for atmega32u4 and several ...
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231 views

Do Computer keyboards have ICs?

I have always assumed that computer keyboards do not, in the typical case, contain integrated circuits. And also, now that I think about it, there must be a set of standard electrical (digital?) ...
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82 views

How to connect a microcontroller to PS/2 port as the PS/2-keyboard?

The voltage of output signals of my CPLD MAX II board is 3 volts. Can I connect this board to open collector of PS/2 motherboard-MCU? So, if I want to send a "zero" signal, I'm sending "one" to the ...
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90 views

Old 8 bit decoder behavior

I'm trying to add an USB keyboard to an old 8-bit Amstrad CPC 464 home computer, like is done here. To make a brief summary: The keyboard is designed as a matrix with 10 lines and 8 bits per line, ...
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What linear sensor for a keyboard? [closed]

I'm trying to make a velocity-sensitive keyboard for playing music. I have to measure the position of each key in order to know how loud the sound should be. The volume of the sound is a function of ...
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242 views

Single key not working on DIY mechanical keyboard (xd75re PCB and Switch both work)

I have assembled my first mechanical keyboard using the xd75re PCB. I used a plate mount, and all of the switches were installed without issue (this PCB has hotswap). When I used keyboardtester.com to ...
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3answers
156 views

How did the Commodore 64 keyboard work?

I'm designing a computer using a Z80 processor (I know, not the same as the one the C64 used, it doesn't matter) I found the following schematic showing part of the C64 circuit, and I'm particularly ...
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199 views

USB hub inside modular keyboard for comunication

I'm working on a personal project which consists on a keyboard that also serves as a hub in order to connect more keyboards. For example, I could have the main keyboard with the letters and symbols ...
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1answer
124 views

What kind of led would be used for this keyboard [closed]

I have a project that involves this keyboard, it has 12 sections on the pcb marked UX (X being 1-12) for what I guess are for leds. If I'm correct what kind of led would I buy for it? Something like ...
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171 views

What connector did this IBM Model M keyboard have?

I got got hold of an old IBM Model M (Model 1391403, to be precise). Unfortunately, the fixed cable was cut off by an unknown idiot. Does anyone know what kind of connector (I assume PS/2?) was ...
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65 views

Understanding replaced leds brightness behaviour (keyboard backlight)

I've followed this tutorial to replace some broken leds on my keyboard. The leds I used are: ...
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1answer
431 views

Is there a way to add Bluetooth functionality to an ErgoDox EZ keyboard?

It would be nice to have some sort of mini-USB accessory that could bluetooth-enable an ErgodoxEZ keyboard. I found some related discussion here: https://www.reddit.com/r/ergodox/comments/8kugs5/...
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102 views

Using a micro computer as a macro keyboard device?

not entirely sure this is the best StackExchange board but I bet some of the great members here could at least point me in the right direction. I'm looking to use one of the microcomputer devices, ...
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1answer
124 views

Using connected PC keyboard input for VHDL Simulation

I am working on a project for school that will involve an input from a push button or related device. We have only a few Spartan boards available, but we have access to Xlinx Vivado to simulate an ...
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77 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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43 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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1answer
97 views

How does this N-key-rollover work?

I'm designing a keyboard. I found some information online about how to make the keyboard be able to detect multiple key presses at the same time (N-key-rollover). I found this schematic, from this ...
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2answers
567 views

Laptop keyboard backlight ribbon cable broken [closed]

I've accidentally broke my laptop keyboard backlight ribbon cable when disassembling my laptop. I want to solder it back by patching with copper wires or maybe copper plates. My question is, it is a ...
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2answers
69 views

Keyboard wireless feedback from computer

This is a theoretical question. I want to ask, is the the modern keyboards communicate with PC such as wireless keyboards can 'get/read' some data from the PC? If not, what do I need to do for that? I ...
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139 views

I need to do a membrane pcb for a keyboard or a flexible PCB like a membrane PCB

I need to design a membrane PCB for a keyboard and/or flexible double sided PCB that works like a membrane PCB. My problem here is that I don't know how to do the buttons, with one contact of the ...
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75 views

USB HID keyboard: why 4 URBs are generated for a keypress instead of 2?

This is system log when keyboard is plugged in: ...
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523 views

What microcontrollers are suitable for a keypad [closed]

I'm a beginner in electrical engineering but I'm into mechanical keyboards and I want to build a keypad (1 row, 6 cols). I recently wrote a macro for a keyboard (ATmega32U4 microcontroller) using the ...
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102 views

Why short 3 terminals per contact on a membrane keypad?

What is the purpose of a three-terminal momentary contact in a matrix keyboard? The motivating example is that I have a damaged membrane keyboard where some of the keys do not work. At first I ...
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water-damaged 3DS, some buttons are now non-functional, any ideas? [closed]

so about 3 months ago I got my Nintendo 3DS wet. I tore it down, cleaned it up with isopropyl alcohol (of highest possible purity) and let it dry off. unfortunately for me, there are some buttons ...
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173 views

i2c interference on coiled wire

Hello good day I been trying to build split keyboard using 2 pro micro. I'd been following let's split keyboard using qmk firmware. And the connection diagram of the i2c is this When doing it on ...
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619 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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2answers
530 views

What is this keyboard connector and how to connect it to MCU?

I have a 1991 laptop keyboard w/o the motherboard. It was attached to the main board with two flexible cables. The keyboard feels awesome and I would like to make use of it. The issue is that I can't ...
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1answer
100 views

Sony vaio keyboard dongle - Power issues connecting to another computer

I have stripped down a very early (2002) vaio all-in-one desktop which has a keyboard with a built in protective cover which I would really like to use on another computer. The dongle was placed under ...
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1answer
69 views

Protecting handmade electronics from accidental water spillings [closed]

Keep in mind that I dont know the least about electronics. I have soldered and used some arduinos before, but that is it. I am preparing to make a mechanical keyboard (or handwire like they say on /r/...
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1answer
934 views

Modern keyboard controller [closed]

Can someone tell me what types of microcontrollers are used in modern keyboards. I would like to make my own keyboard and I think the best for me is something from AVR like atmega32u4, but I want to ...
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2answers
99 views

Simulating keyboard strokes with shortcut key combinations

I rigged up a tiny little project using a scrap Dell keyboard, where I tore the keyboard apart and salvaged the USB control board. The actual keyboard is gone. Then, I traced the circuit for the "...
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253 views

Connecting a coin receptor to a key press

I want to connect a coin receptor to a keyboard press. I want to have an arcade cabinet with my computer game running. It should only add credits when a specific key is pressed, which can be ...
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2answers
410 views

Burnt Diode in MIDI Keyboard? [closed]

A while back I think I may have plugged the wrong power adapter into my MIDI keyboard and it started to smoke and then never turned on again. So... I popped it open and it looks like it's a burnt ...
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151 views

Diode populated keyboard matrix: Wire two separate buttons to the same output?

I have an encoder board for a 16x8 row/column switch matrix. An absolute beginner to electronics but using all of the great online resources for research the best I can. However, occasionally it turns ...
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1answer
138 views

Do I need diodes or resistor for PWM controlle RGB LED?

I am planning to build a custom keyboard, using a pro micro and QMK firmware, and on my plan there would be an excess of 3 PWM pin. So I thought I can maybe put RGB leds on it on parallel. But the ...
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371 views

Adafruit Trinket Analog Button Inputs

I am using a Trinket's (not pro) analog inputs to read differing resistances from button presses. When any of the buttons are pressed, I want the internal LED to light up. I have the buttons ...
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1k views

Is the communication between the USB or PS/2 keyboard and the computer simplex, duplex or half-duplex (unidirectional or bidirectional)?

I am curious to know if the communication between the computer and keyboards is unidirectional or bidirectinal. Until a few days ago i thought the communication is unidirectional because only the ...
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427 views

How to count pressed keys on FPGA spartan board

I`m using FPGA Spartan 2 board and want to count the keys pressed from Keyboard this is my VHDL code : ...
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1answer
72 views

Game Show Button DIY help

The club I am a part of at my school is currently trying to host a variety/dating show in which contestants will have the capability of controlling a button. There should be about 12 buttons to make ...
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Power consumption of an idle USB keyboard

I have asked recently about the voltage of a PS/2 keyboard, now that was a too complex circuit for me, and a lot of weird things happened, for example if I disconnected the red wire after the adaptor, ...