kelvint How does a hardware know when an output is being patched into the input? How does the hardware know something is connected?
It normally doesn't. You'd use a "normalled" jack socket, such that when nothing is plugged in, an internal signal is connected to the jack's input. For audio applications, for instance, you'd usually connect the input to ground when no signal is plugged in. In the case of CV inputs, if you have a potentiometer on the same input, you'd connect the input signal to a voltage source instead and feed it to the the potentiometer the same way you would with the external signal coming from a jack plug.
Our Pepper DIY kit does just about that. The input signal goes to one of the terminals of a potentiometer which is used to scale down the input signal before feeding it to the analog inputs. The normalled connection on the input jack is such that the input to the potentiometer is connected to a 10V voltage source. So the ADC doesn't know whether the voltage it's receiving is due to an external signal or to the internal voltage reference or how much it has been scaled by the potentiometer. See schematics, documentation and shop (hopefully soon available as a full kit).
