Device for measuring time and temperature using a microcontroller

In this paper a device of data acquisition with low cost and easy management was developed for using in experiments of physics where time or temperature measurement is required. The device is composed by three main parts: (i) sensors to measure the physical variables of time and temperature; (ii) a data acquisition card with microcontroller to manage commands and (iii) a computer in order to store data. The sensor, composed by an infrared and a phototransistor, changes its logical state when the signal is interrupted. The board used includes a microcontroller of Microchip brand, PIC18F14K50, which has comparators, analog to digital converters, timers and an Universal Serial Bus (USB) port. The computer was used as a tool to store data and see variables by means of a spreadsheet. The microcontroller programming was made with MPLABX software of free license. The usefulness of the device was tested in the free fall experiment in order to determine the value of the gravitational acceleration.