DDR DIY Pad: Help soldering wires to a USB controller

Hello and thank you for your help. I will be soldering wires from a DDR pad that I am building to the control board of a USB controller. However, the board is not quite what I was expecting (I am a noob with soldering wires).

Pictures

If you look at the second picture, this is a close-up of the board where the four directions connect. I believe that when you push a button, the rubbery thing makes contact with the board, completing the circuit and sending the signal. So, with the circuit completion now coming from stepping on a pad arrow, where do I need to solder the wires to the board to send the signal properly? And for that matter, where should the ground go?

Thank you in advance!

Hey there!

You will need a multimeter to test which part of the trace on the buttons is the ground, assuming the controller has a common ground. After you figure out which part of the trace is the common ground the other side is where you will solder the wires from your DDR pad. The ground wire coming from the dance pad can be soldered to any ground point on the controller afterwards.