Research On The Measuring System Of The Multiple-point Temperature And Humidity For Solar Drying Equipment

In agricultural products drying, temperature and humidity testing has been very widespread application, especially temperature and humidity in the oven and solar collector are two very important factor, so achieving multi-point temperature and humidity testing in the oven and solar collectors is an important function for the drying equipment of agricultural products.Departure from the status of the development of domestic and foreign agricultural products solar drying device, combining the characteristics of the currently popular on the market temperature and humidity sensors, I has designed based on the solar drying device of multi-point temperature and humidity detection by the C8051F020MCU,including hardware circuit design between the single-chip and peripheral devices, and sensor reading and writing program,and the LCD cycle program, and a program of the single-chip writing data to U disk as well as a program of a PC reading U disk data. The user can take a U disk to store temperature and humidity data to open by a text format on a PC to view temperature and humidity data in different locations at different time periods within the oven and collector, and to display the temperature and humidity data in real time at the scene.From two factors, the system functionality and material costs, I has used MCU C8051F020as the controller, selected a DHT21digital temperature and humidity sensor to measure,taken Silicon Aboratories IDE combining Keil Vsion3as software development platform for system development, used the C51programming language, utilized CH372-USB conversion chip to realize the temperature and humidity data acquisition and storage.This paper has done work as follows:1) I has designed a measure system of temperature and humidity of solar energy drying device based on C8051F020MCU, used DHT21digital sensors to detect temperature and humidity, which has a fast response, high reliability and excellent long-term stability.2) I has designed a kind of power supply circuit which can generate+5V and+3.3V DC voltage; a kind of reset circuit which can realize power-on reset and switch reset function; a matrix keyboard circuit; a sound and light alarm circuit; a kind of the temperature and humidity sensor array circuit consisted of6measuring points which Divided into2road bus; a kind of LCD1602C liquid crystal display circuit; a kind of interface circuit between the CH372-USB and the MCU; a kind of switch circuit which can control dehumidifier.3) The design has completed the temperature and humidity measurement, data storage and a program design which was read data by a computer, finally realized that it displayed the temperature and humidity values with TXT text format in the PC.4) After the debugging of the hardware and the on-line debugging of program, the design has completed the function of a multi-point real-time detection, achieved the established design requirements. The experimental results showed that:this method improved detection efficiency of the drying box and the collector, made the device portable and simple, provided a lot of convenience for the further processing of the data.