Design and Implementation of Alcohol Concentration Monitoring System Based on MCU

With the development of science and technology, intelligent products becomes more and more popular. Alcohol concentration monitoring system based on the MCU STC89C52 and gas sensor has many functions such as alarm by sound and light、LCD display function and so on. The system can set different thresholds according to different environment in order to meet the different environment monitoring.The warning lights can be taken as two levels of alarm respectively(“tipsy ” and “pissed ” )if the value measured has exceeded the threshold, and the value displays. The system according to the design scheme has the advantages of high sensitivity, good working performance, low power consumption, low cost, high price etc., which can be used in traffic detection, fermentation monitoring in wineries and foods factories etc.. Introduction Sensing technology has gradually become mature with the rapid development of information technology in the 20th century, and it has been widely used in the production of life . The sensor has played a pivotal role in all fields, and high precision, high reliability, miniaturization, low power consumption and intelligent digital has become the direction of its development. In order to check for drunk driving, police often use a portable breath alcohol detector by detecting driver exhaled gas in order to judge the drinking driving .It can only judge whether a driver is drunk with the use of alcohol breath tester at present , alcohol concentration only can be measured by some blood test . In view of this situation, the design of the alcohol concentration monitoring system can monitor the concentration of alcohol in the environment, besides it can display the results and numerical classification of warning, you can also set the threshold value of alcohol concentration on manual arbitrarily to delineate the safety limits of alcohol concentration on different environment.It also has other functions just as hierarchical alarm etc. . Design principle and process Design of the hardware The framework diagram of this alcohol concentration monitoring system is shown in Fig.1. The system is mainly composed of capacitive touch sensor, gas sensor, analog digital converter, MCU, LCD display, keyboard module and sound and light alarm. 6th International Conference on Machinery, Materials, Environment, Biotechnology and Computer (MMEBC 2016) © 2016. The authors Published by Atlantis Press 2149 Fig.1. Principle block diagram Data acquisition is completed by MQ-3 alcohol gas sensor which is an alcohol sensor , alcohol sensor will detect the alcohol concentrations and convert them to electrical signals,the signals are transmitted into an analog-to-digital converter, the converted digital signal is then transmitted into the MCU,it is analyzed and processed by MCU,and the results will be displayed on the screen at last. Comparing with the threshold of alcohol concentration set by the keyboard, the buzzer will alarm and LED will flash constantly if the alcohol concentration of the environment is detected that the results have exceeded the threshold value,which is controlled by the MUC. The physical map of MQ-3 alcohol gas sensor module as one of the core devices is shown in Fig.2.The sensitivity of MQ-3 for various gases is different, and it’s more sensitive to alcohol than others as shown in Fig.3. Its sensing principle is that the output resistances coming from the gas sensitive resistance change with the concentration of the ethanol gas. Fig.2. Physical map of MQ-3 Fig.3. Sensitivity curves for various gases STC12C5A16AD is chosen as the MCU in this system which is another core module.The chip has 52 cores and 8 bits ,10 multi-channel A/D conversion module is integrated in the internal which is suitable for maintenance circuit in common use. The principle diagram of the MCU system composed of STC12C5A16AD is shown in Figure 4. AOUT is the voltage detection signal which is output by MQ-3 sensor module, and it is transmitted into the port ADC7 then processed there. DOUT is a digital signal output by sensor module, the signal can be output as the alarm signal directly according to the concentration of ethanol gas. The alarm threshold can be adjusted to the potentiometer on the module.