I have a small speaker which has a P2 cable coming out from it. Usually I connect this P2 cable to my celphone or computer so it outputs sound to the speaker using the P2 cable/connection. See this:
My question is this: I just want to send any kind of audio (square wave..., anything) to this speaker. Can I connect a digital pin from my arduino to send HIGH pulses to this P2 cable without any resistor or aditional hardware? I see this P2 terminal has 2 black stripes, how should I connect it to my arduino? Which part of this P2 terminal is GND?