This application note describes a Digital Boat Speedometer concept which uses a monolithic, temperature compensated silicon pressure sensor, analog signal–conditioning circuitry,microcontroller hardware/software and a liquid crystal display.This sensing system converts water head pressure to boat speed. This speedometer design using a 30 psi pressuresensor (Motorola P/N: MPX2200GP) yields a speed range of 5 mph to 45 mph. Calibration of the system is performed using data programmed into the microcontroller’s internal memory.