How to attach wires on a keyboard controller PCB

Question

I want to make a module with 3 momentary buttons that will be record the numbers of pushes on a pc.

For this first i though about using an arduino but also I am trying to use a keyboard motherboard/ controller to give a key signal, f12 on first button, f10 on second and f10+f12 on third, that will act as a keyboard input to the program on the pc.

As I couldn't solder directly on the pcb because it has a really thin sheet of coper covered in carbon powder, I had to mechanically attach the wires with 2 parts of metal on both sides and wrench them also using a conductive adhesive of 1Mohm rezistance.

After that only 2 keys worked and i have to use f10+f12 for the third button.

They all have a common wire in color white, and 2 wires separately one for f10 and one for f12. my problem is at the third button where i need to connect f10+f12 wires on one side and the common wire on the other side, i will permanently connect them also for all other contact and get the same output on all buttons.

So I used 2 diodes on the 2 wires and now all work except the third button where i get only f10 output and f12 oscillate on and off, sometimes it doesn't even show, if I keep the button pressed f12 turn off after a time but it work on the first button alone, if i bypass that diode it works but then i get 2 identical outputs on 2 buttons that use f12, i heard of WIRE OR method to attach a resistor connected to ground at the end but it doesn't work at all

yellow wire is for f12 blue is for f10 and white is common wire

Button pressed http://imgur.com/a/zRzCEdy This is the button

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This is the image of the instalation

This is the schematic, i atached the wires on the keyboard controller pcb at the coresponding pins for f10, 12 keys, using conductive adhesive

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I didn t want to use a key combination but my conection of the wores with the board was not good and only 2 of the 3 wires i conected worked and i was thinking of getting a combinatios for the third button. Also i wires the wire on f9 key and i get f10 output , maybe if i ise that adhesive paste that has a big 1mohm resistance can influence the reading ? If there is anothe way of ataching those wires on the keyboard mdboard, i tried soldering but they are just to thin and come lose from the pcb I wanted to use an arduino but i am making the mechanical part of the project for my brother who wants to use this on his software, and he wouldn't want to use arduino for some reason also to not complicate the code , like this it is easier to get input but doesn t work when the program is in background on the pc.. Is there any boar that would simulate a keyboard input as f10 or any other key instead of serial comunication ? Because also i saw that arduino pro micro can be used to send keyboard inputs trought serial wich i brlive would be better because it will not intefere other stuff on pc and will be conected to the program directly

I believe the keyboard pcb deal with debouncing of the buttons itself, if i use another board i will have to deal with that in the program

Answer 1

A keyboard controller tend to use a matrix of connections and scans through them at some interval. Without knowing the setup of the matrix and the controllers behavior, attempting to get the specific combination of 2 individual and 2 combined keys you want is not trivial.

You would be better off using 3 individual keys (say 1 2 3) and use a software re-mapper or hot key or macro tool to change those to f10 f12 and f10+f12 scan codes.

Or use an arduino or digistump or similar usb enabled microcontroller with usb-hid keyboard to provide what you want without all these wiring guess work. At under a dollar for a complete board and plenty of examples online, its dead simple.

Answer 2

I just used another keyboard controller and i first attached the wire from the bottom using a piece o metal and tighten them so they won't move when soldering them i fixed in position and soldered after that i also aplied the conductive paste to fix the wire afterit will dry and i tighten the upper piece pf metal using a silicone in betwen . Like this i finally got all the keys output as i had to on the pc