I would like to add a 4-key membrane keypad to my existing project, to control alsamixer volume.
I would like 3 buttons to correspond to different alsamixer volume levels, and last button to be mute/unmute. I understand that I should use resistor(s). I read about examples which utilize breadboards and prototype pcbs but I need my setup to be very compact and fit inside the case like on photo, except for the button pad itself obviously - so those ain't an option.
Now, my questions are:
How many resistors and in what configuration should I use?
How would you advise to connect me all this stuff to gpio? Can I just twist the wires together then cover them with electrical type, or is soldering still required for this application?