I have a 3x4 matrix keypad wired up to 7 GPIO pins - each through an 18k resistor. The row pins are set as outputs and the column pins set as inputs. The inputs are configured to pull to ground via the internal pull downs. I have some code using wiringPi to detect interrupts on the input pins when they go HIGH. This works fine... although the interrupt is triggered if I so much as wave my hand in the vicinity of the wires. This is also a problem if I move the wires slightly and the magnetic field in one induces a current in another.
Can anyone speculate as to why this is detecting such crazy low currents as a state change on the inputs... and how I might solve the issue.