Design Of Indoor Formaldehyde Detector Based On MSP430

Indoor air pollution has been a hot discussion in modern society, in which the problem of high levels about formaldehyde is needed to be solved right now. Formaldehyde exceeded the body will produces a great harm, so the detection of indoor formaldehyde is particularly important. For the problem of indoor formaldehyde, designs a real-time monitoring system based on the electrochemical formaldehyde sensor. The system uses MSP430F149as the main chip、DW200KB as the wireless transceivers、PCD8544as the LCD module、7805and LT1117combined as the power module. The principle of formaldehyde sensor is:formaldehyde takes a chemical reaction with internal electrolyte solution after diffusing into formaldehyde sensor, then this chemical reaction will consume electrode, transfer electrons and produce a microampere-level current signal. The output current signal will be transferred to voltage signal after Ⅰ/Ⅴ conversion and amplified several times by gain circuit. The output voltage signal will be converted and transmitted to microcontroller by ADC, converted to formaldehyde concentration data and displayed by LCD. At the same time, formaldehyde concentration data can be transmitted to the host computer by wireless transceivers, which allows the operator to collect and manage the data on the host computer. Residents can consider when to move into the house based on the real-time monitoring data, and this avoids the harm to human health from exceeded formaldehyde indoor.The paper describes the overall design of formaldehyde detector, electrochemical formaldehyde sensor’s interface circuit, the peripheral modules and host computer. The completed work includes as follows:(1) Hardware design, including formaldehyde sensor’s interface circuit, amplification circuit and the circuit of peripheral modules. The peripheral modules include power supply module, LCD, wireless transceivers, keyboard, and serial communication module.(2) Design of host computer. In the part, designs the login screen, data capture options, site selection options, data management options, monitoring and managing options, alarm options and tool options in the indoor formaldehyde gas concentration monitoring center.(3) Analyzing the data, adopting reasonable means to solve indoor formaldehyde problems based on the real-time data collected in different places. (4) Analyzing the methods of fitting curve:least squares method and interpolation method. Based on the similarity of fitting curve and computing tedious, adopts interpolation method to fitting curve of formaldehyde concentration.(5) Proposed the problems of this system and the areas for improvement in the future.After debugging and testing, proves that this real-time monitoring formaldehyde system can collects indoor formaldehyde concentration data effectively and accurately. The system provides a reference to other lower-power and real-time monitoring system. Also, detecting other harmful gas can the reference this system and establishing their own harmful gas monitoring system based on this system.