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Multiple signals to same pcb?

Former Member

Hi, so I have little pcb with 2 leds and 2 switches on it.  A common wire goes to one side of all of 4 items and a single wire goes to other side of each item, for a total of 5 wires.  In addition, there is what looks like a resistor connecting both sides of the leds.  My issue is that to get an led to light up, I have to connect the common wire to the signal of pin 12, for example, and the individual wire for that led to ground.

 

This is causing great confusion and pain and suffering on my end.  I presume that I can not connect the signal of 4 different arduino pins to the common wire on the pcb without doing something else, if at all?  I can connect the switches normally, but I presume using the same connection as both signal for the switches and ground for the leds will also not be a good idea.  Anyway, board designed and engineered precisely and replicating with different wiring would be very difficult for me.  Thanks for any advice!

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  • you may have something like this (Based on description)image

    hope this helps

     

    did you make the board yourself and are having difficulty getting it to work or is it a bought product?

     

    can you provide a picture or a schematic like the one i just provided but showing how you have the parts connected

     

    thanks

     

    oh and post your sketch so we can see what your trying to do in the code as well

  • in reply to Robert Peter Oakes

    I was going to mention the resistors on the switches because I didn't recall Joe mentioning them in his first post, but I stepped away to eat some chicken pot pie instead.

     

    What app are you using to make your whiteboard drawings, Peter?  Something on a surface I take it?  I don't suppose there is a copy cat app for my iPad.  I like it.

  • in reply to 4ringfan

    The board was connected to another proprietary computer that I am trying to replace.  Right now it is like the diagram below, and I can connect one led to a pin, e.g. pin 12, as shown.  If I switch the wires, so the common wire is ground, then the led doesn't work.  Actually now that's making me think those are diodes, and not resistors.  Regardless, what I don't know is if I can connect the Pin12 wire to Pin11 also, and then both the other wires to ground, or that zap something.  I'm thinking now the safest thing is to just cut the pcb and separate everything and solder new wires to make 4 separate circuits.

    image

  • in reply to Former Member

    It would help to know what you are intending for the two buttons and two LEDs to do.  I think you are definitely going to need to re-wire the board.  As drawn, the schematic, to me at least, looks wrong.  Can you get us a picture of the existing PCB, preferably both sides?  Maybe we can give you direction on what needs to change to make it work.  LEDs are diodes and they only work in one direction.  If you look carefully at the Light Emitting Diode, one side of it should be flat.  That side is the cathode and it should go to ground and on one side or another you need a resistor, otherwise the LED can go POP.  The resistor should be about 560 Ohms in a 5V circuit for an LED.  There is an excellent book by Massimo Banzi "Getting Started with Arduino".  You might want to check it out.  He has a few examples that would be helpful for you.

     

    image

  • in reply to Former Member

    Looking at those diodes, the only way I could see that board working is by connecting the common wire to GND.

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