Baratieri, Cássio LucianoSbardeloto, Eduardo Sachet2025-03-102024https://repositorio.uricer.edu.br/handle/35974/759Soybeans have been cultivated in Brazil for over a hundred years and the country is currently the world's largest producer of the grain. Therefore, it is essential to use technologies aimed at agriculture in order to ensure the high standard of products destined for the market. Determining the moisture content of grains is of great importance in the agricultural sector, since this parameter is essential to define the quality of the product. During harvesting, it is important to know the moisture content contained in the seeds, in order to reduce losses caused by the harvester. During storage, it is recommended that the grains have a moisture content of up to 13%, to avoid contamination by fungi, bacteria and insects. At the time of sale, the warehouse applies discounts that can reach 2% for each moisture point that exceeds 14%. Given the importance of this monitoring, this work proposes the study and development of a portable and low-cost meter to determine the moisture content of soybeans in a practical and fast way. In the prototype developed, the microcontroller reads the sensor's operating frequency, converting it into a moisture percentage value, which is displayed to the user on a display. The sensor consists of a parallel plate capacitor, where the sample is deposited for analysis. The oscillator circuit consists of an NE555P IC configured in astable mode, responsible for generating a square wave according to the behavior of the sensor capacitor. The ESP32 Dev Kit V1 development board was used to receive the programming code, written in C++ language. The prototype was calibrated by determining the moisture content of six soybean samples using the oven method at 105 °C. Based on the results obtained, a linear regression line was created relating the moisture percentages found to the average frequency obtained by the sensor capacitor in three measurements of each sample. The equation of the line was inserted into the microcontroller programming in order to convert the read frequency into moisture percentage. To calibrate the prototype, tests were performed to measure the moisture content of soybean samples containing different water contents. The test results were compared to those of a reference equipment. Therefore, it was concluded that the prototype developed presented reliable and accurate operation in samples with moisture content between 10.8% and 21.2%, but did not show good performance in grains with approximately 30% moisture content.pt-BREngenharia ElétricaESP32Capacitor de placas paralelasTrabalho de Conclusão de Curso