help: MP3 player push button's control issue

[engasm]

hi guys,
i really need some help with this
i want to control mp3 push buttons using pic
i tried to use transistors as switches instead of push buttons,
1st i measured how much volt each button has on its terminal and it was like this
2.55v
2.60v
2.65v
one for each,
2nd i determined positive and negative terminals of each button
--
i used a uln2003a and on another test i used separated 2222a transistors
in both experiments
something goes wrong
first let me say that i soldered wire out of each push button so i can easily control it
and for every one to know, if i but the two wire that come out from each button it acts exactly as it should act, but this is done by hand
i wanted to do this using pic so i had to use transistors so i can control using 0's and 1's
---
to make the problem clear now, when i connect everything correctly, and send signal to the transistor to allow the volt to flow between the buttons terminal it reacts differently,
meaning if it is a move forward button it doesn't do that instead it increases the volume !!!
it acts completely different like if there is mis-functionality !!
---
it might be an increase or decrease of voltage problem
but could the transistor take of gave some extra voltage when it acts as a switch ?
and is there any different component that i can use instead of transistor and push button and still controllable by pic ?!?!
please help with this
AFAP

 

[DemonicSandwich]

The buttons are likely multiplexed rather than common ground or common line.

Basically the buttons are floating until one pin is pulled to high or low while the other pin is scanned to see if the button is being pressed.

You can control them using an optocouple/optoisolator.

 

[rogs]

Or it might be a matrix - so that none of the buttons are actually switched to a common point.

You should be able to copy each switch in a matrix, using CMOS analogue switches. Look up the quad CMOS switch type 4066.

 

[engasm]

the buttons are neither multiplexed nor matrix, i manged to find a common but each button negative terminal is grounded by resistor, a very small one so we have three buttons with one common connected resistor and two separated buttons with another two resistors grounded, the wired thing here is that all of there buttons are sharing the same ground indirectly meaning
when i check connectivity using dmm i found that all of the negative terminals are connected together !
i don't know tell now where is the missing piece but could it be grounded in such a way that is too much sensitive to the voltage
or might the transistor cause some voltage drop !

thnx 4 ur fast response

 

[rogs]

You say it's not multiplexed or a matrix, but judging from your descriptions, I'm not convinced they're simply connected to a common. In any case, if there are 'resistors' in this 'common' line, you probably can't use transistors simply as open collector switches, with their emitters common to gnd.....

Anyway, to simulate the connection of the two wires 'joining together' from each switch you described earlier, just use the 4066 CMOS switch I referred to above. Connect the two wires from each switch to the in/out terminlals of the switches within the 4066, and drive the control terminals from your PIC outputs.
Power the chip from the same power supply rail as the PIC.

That will eliminate the problems you seem to be creating, by trying to copy 'voltages' by using transistors.