To measure pressure, determine the type of sensor you are using: ratiometric, raw bridge, or signal-conditioned. For ratiometric sensors, measure the supply voltage to improve accuracy or use a stable and low-noise supply voltage. Raw bridge sensors are more demanding but can be handled with the Bridge Circuits App Note. Signal-conditioned sensors are easy to handle with three wires: Vsupply, ground, and signal. Pressure sensors are available from manufacturers such as NXP and Omega. For 4-20 mA current signal sensors, an external power supply is required, and you can refer to the 4-20 mA App Note for guidance.