Design And Application Of Wireless Indoor Environmental Monitoring System Based On The Single Chip Microcomputer

We know that the temperature and humidity and concentration ofharmful gases is essential to calibrate the parameters of the environment，that has important significance for its accurate measurement. This systemis designed for people’s long-term place to live or indoor air quality in theworkplace.In this paper, in the background of the indoor environment monitoring,we designed a wireless environmental monitoring systems which uses theSTC12C5A60S2chip low-power microcontroller-based.System consistsof three modules: the first is the data acquisition module, which includestwo content, temperature and humidity acquisition and formaldehydeconcentration acquisition. The measurement of temperature and humidityusing digital temperature and humidity sensor DHT21, single bus40digital output to MCU, after data processing, the data will be sent outafter they are sent to wireless transmission module through the SPIinterface. Formaldehyde concentration measured by the sensor MS1100,MS1100acquisition analog signal output into STC12C5A60S2,single-chip analog to digital conversion, digital quantity measurementvalues obtained after data processing.The second is the wireless transmission module, transmission modulehas two elements: Data transmission of data acquisition module and datareception module receives data. Both modules are using Nordic VLSI’ssingle-chip RF transceiver nRF905as main control chip.nRF905unity withthe characteristics of transmitting and receiving functional throughsoftware programming, according to the need can achieve its function.The third is a data processing display module, whose main content isreceiving module receives the data via nRF905and pass receiver moduleprocessor, sent to the display after STC12C5A60S2processing the data.Display module is accomplished by1602LCD, real time display thevalues of temperature and humidity and the concentration of formaldehyde. Meanwhile, the module also joined the alarm module,when the temperature and humidity values and formaldehydeconcentration exceeds the standard value, the buzzer alarm to remindpeople to take the necessary measures to avoid air pollution on humanharm.The system software design using C language, complete themeasurement of indoor temperature and humidity, and the concentrationof formaldehyde, and displayed in real time. System performanceindicators: Temperature measurement range-40~80℃, accuracy of±0.5℃; Humidity measuring range0~100%RH, accuracy of±3%RH;resolution is0.1; The system is small, low power consumption,long-distance wireless data communications, low project cost, highreliability. It is suitable for monitoring indoor environmental parameters,there is a good market prospect.