Read a rotary potentiometer

This knob lets us choose a voltage for the Arduino to read. Fit the potentiometer in these three holes, with its terminals facing the Arduino. Each terminal goes in a separate numbered strip. The middle one is called the wiper; its voltage changes as we turn the knob. Connect this outer terminal to the Arduino’s five volt output with the red wire. Inside the breadboard, one metal strip joins these five holes. That’s why the jumper can use a free hole in the same numbered strip. The long power rails aren’t needed for this circuit. Connect the other outer terminal to Arduino ground with the black wire. Ground gives us the zero-volt reference for measuring the middle terminal. The red and black wires will supply the two ends when we connect U S B. Connect the middle terminal to analog input zero with the blue wire. The Arduino measures the voltage here as you turn the knob. Check the three wires, then connect the square U S B plug to the Arduino and the other end to your computer. That powers the circuit. To read your real knob, choose Arduino Uno and upload the supplied sketch. Keep U S B connected for the readings. Watch the centre pin as the knob turns: its voltage rises from zero to five volts. Halfway gives about two and a half volts. The Arduino turns that voltage into a number from zero to one thousand and twenty-three; halfway is about five hundred and twelve. Pause here and try the knob yourself.

This knob lets us choose a voltage for the Arduino to read. Fit the potentiometer in these three holes, with its terminals facing the Arduino. Each terminal goes in a separate numbered strip. The middle one is called the wiper; its voltage changes as we turn the knob.

Connect this outer terminal to the Arduino’s five volt output with the red wire. Inside the breadboard, one metal strip joins these five holes. That’s why the jumper can use a free hole in the same numbered strip. The long power rails aren’t needed for this circuit.

Connect the other outer terminal to Arduino ground with the black wire. Ground gives us the zero-volt reference for measuring the middle terminal. The red and black wires will supply the two ends when we connect U S B.

Connect the middle terminal to analog input zero with the blue wire. The Arduino measures the voltage here as you turn the knob.

Check the three wires, then connect the square U S B plug to the Arduino and the other end to your computer. That powers the circuit. To read your real knob, choose Arduino Uno and upload the supplied sketch. Keep U S B connected for the readings.

Watch the centre pin as the knob turns: its voltage rises from zero to five volts. Halfway gives about two and a half volts. The Arduino turns that voltage into a number from zero to one thousand and twenty-three; halfway is about five hundred and twelve. Pause here and try the knob yourself.