A microcontroller-based system for liquid level detection using infrared sensing

摘要

This project aims at developing an intelligent liquid level detection system using the concept of infrared optical sensing. It involves a comprehensive study on the optical transmittance of water and Polyethylene Terephthalate (PET), and the integration of optical monitoring hardware system with software development to implement the concept of infrared optical sensing for liquid level detection. An extensive study was done and it was determined that for this system, the optical transmittance of water should be low while the optical transmittance of PET should be high. The optical spectrum which is suitable for this application was determined to be in the range of 1350nm to 1500nm. A signal conditioning circuitry was designed to channel the signal from the photodetector to the microcontroller. A program was developed using C-programming language in order to carry out all the input/output control functions. A graphical user interface (GUI) was designed to interface with the microcontroller such that the system was user-friendly. Furthermore, a driver circuitry was designed to provide stable voltage and current supply to the laser diode that was acting as the infrared light source.