The V0 (also labelled as VEE) connection is for contrast control, and a potentiometer (10K) is usually attached to this terminal. Normally, the R/W terminal is tied to ground. For backlighting purpsoe ...

• Potentiometer ($1) • LCD display ($10) ... (temperature sensor) and connecting them to a programmed Arduino gave me a gadget that monitors the environment of a single plant.

The primary control interface is a Softpot 500 mm membrane potentiometer, ... and preferences which the Leonardo prints on a 3.5″ LCD ... is the Arduino Leonardo that they connect to.