Alcohol concentration tester control panel design

With the rapid development of China's economy and the continuous improvement of people's living standards, various motor vehicles have become an indispensable part of people's lives. Especially the appearance of private cars has undoubtedly greatly improved the efficiency of people's life and work, but the problems brought by it have also followed, and this is the problem of safety. Many years ago, traffic managers could only rely on subjective judgment, naked eye observation and blood alcohol content detection in the hospital to determine whether a driver had drunk alcohol. These unscientific and untimely methods caused a lot of unnecessary misunderstandings and troubles. The occurrence of the above-mentioned problems is helpless because there is no safe and accurate detection instrument that can detect alcohol concentration on-line that is easy to carry. This instrument uses the YX-GS-800M low-power ethanol gas sensor as a sensitive unit, which converts the gaseous concentration of ethanol contained in the gas into an electrical signal, which is sent to the single-chip microcomputer for processing through the A/D conversion circuit, and the measured gas is visually displayed by the digital tube. At the same time, it is judged whether to issue a voice alarm signal according to the specific situation.

1. Alcohol tester hardware resource configuration

1.1 SCM system

Hardware selection: 89S51 single-chip microcomputer is selected as the microprocessor, the sensor is YX-GS-800M alcohol sensor and the single-chip integrated two-terminal temperature-sensitive current source sensor produced by American Analog Devices Company. The voice alarm module uses a PM50100 multi-function voice chip produced by China Youth Century Company with relatively powerful functions. 8279 and 74LS138, which are familiar to everyone, are used to realize the keyboard and display part, and ADC0809 is used for analog-to-digital conversion. The battery voltage detection circuit is composed of chip LM316 and peripheral circuits.

1.2 Alcohol sensor selection

This design is a portable detection instrument, so the most important part of each part of the device is the small size and powerful function. Considering that this design will be used in different environments after the product is formed, we have carefully considered factors such as the temperature range where the alcohol sensor can work normally, the sensitivity to alcohol, and low power consumption when selecting the sensor. Reference comparison.

After screening, the YX-GS-800M low-power ethanol gas sensor is selected. The performance indicators of the sensor meet the requirements of this design. The following is a brief description of the functions, characteristics and technical indicators of the YX-GS-800M ethanol sensor: a .Characteristics: High sensitivity to ethanol, fast response to ethanol, small size and low power consumption. b. Working environment: Temperature: -20℃~+50℃ Humidity: ≤95%RH. c. Technical indicators: as shown in Table 1.

1.3 Design of temperature detection circuit

The selection of the temperature sensor is basically the same as the selection of the alcohol sensor mentioned above. It is small in size and low in power consumption. The power supply part should be suitable for battery power supply. The output resistance should be large and the driving ability should be strong. The temperature measurement range should be large enough and the accuracy should be high. Non-linear errors are smaller. The temperature sensor selects the AD590 monolithic integrated two-terminal temperature-sensing current source produced by the American Analog Devices Company. It has high precision. The AD590 has five gears of I, J, K, L, and M, among which the M gear has the highest precision. In the range of -55°C to +150°C, the nonlinear error is ±0.3°C.

1.4 Design of A/D conversion part

ADC0809 is an 8-bit A/D conversion chip, which uses successive approximation to complete A/D conversion. ADC0809 is powered by a single +5V power supply. There are 8 channels of analog multi-channel switches with latch function on-chip, which can convert 8 channels of 0~5V input analog voltage signals in time division. It takes about 100 microseconds to complete a conversion. The chip also has a multi-way switch address decoder and a latch circuit, etc., and its output has a TTL three-state latch buffer, which can be directly connected to the data bus of the single-chip computer; through an appropriate external circuit, the ADC0809 can control 0~5V bipolar analog signals for conversion.

1.5 Design of battery detection circuit

The voltage follower composed of LM316 and peripheral circuits can detect the battery voltage at any time and send the detection result signal to the microprocessor for processing through A/D conversion. When the battery voltage is lower than the set alarm value, a signal is given by the microcontroller to realize voice alarm and display. LM316 is a general-purpose integrated voltage comparator with a wide range of uses. Its power supply voltage allows a wide range. It can be powered by positive and negative dual power supplies or a single power supply. If it is powered by +5V single power supply, it can directly drive TTL devices; if it is powered by +15V single power supply, it can directly drive CMOS devices, and it can output 50mA current. For ease of use, +5V single power supply is used in this design.

1.6 Voice alarm circuit design

To maintain the leading performance of the design, it is necessary to choose a powerful voice chip, which can realize truly humanized human-machine communication. Therefore, this design chooses PM50, a new generation of intelligent voice chip capable of human voice. PM50 series intelligent voice chip is the latest intelligent voice product developed by China Youth Century Technology Co., Ltd. in 2003. The chip is composed of a dedicated voice single-chip microcomputer and a FLASHRAM memory set. Smart features of programming. The recorded voice can be divided into 1~8 segments or 128 segments, with eight input ports and nine output ports, and the functions can be customized by the user.

2. Alcohol concentration tester system software design

According to the connection of the hardware circuit diagram and the requirements of the system function, the software mainly includes: the main program, the result measurement read-in program, the display program, the delay program, and the average calculation program. The main program mainly completes the system initialization, reading the keyboard, judging, calling the program module, looping process and other operations, which is the general skeleton of the whole software. The main function of the main program is to initialize the state parameters of the single chip microcomputer, register initialization and program custom state parameters, and call the subroutine flow and other functions, and provide the subroutine entry address to improve the system function. The display program is completed by using the 8279 integrated chip to realize man-machine communication, realize automatic scanning of the keyboard/display, and identify the key number of the closed key on the keyboard, which can not only greatly save the operating time of the CPU on the keyboard/display, thereby reducing CPU The burden, and the display is stable, the program is simple, and there will be no misoperation, which is adopted by us for these advantages.

Summarize

The hardware circuit is simple, which reduces the production cost, has market competitiveness, and is easy to operate. The instrument will automatically display the measurement results within a short time after exhaling into the instrument. At the same time, the human voice mode broadcasts the results and gives reasonable advice on whether it is suitable for driving. The instrument can also be designed in a very targeted manner, which can display and broadcast the ambient temperature at any time. It is aimed at different users in different provinces and regions. Users can set the alarm concentration according to specific needs, fully consider the power-saving design, and are equipped with battery detection. Circuit, when the battery power is too low, it will give a display and voice alarm prompt to replace the battery. When the instrument does not detect a signal within 4 minutes, it will automatically enter the sleep state and store the latest 10 measurement results for reference. Therefore, this design has strong practicability.

The above is the design example of the alcohol concentration tester introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have the development needs of alcohol tester circuit board solutions, you can trust us. We represent a variety of single-chip microcomputers, voice chips, dual-mode Bluetooth ICs, and wifi chips. Brands include Songhan MCU, Yingguang MCU, Jerry Bluetooth, Ankai Bluetooth, Allwinner, and Realtek. Our technical services include: PCB design, microcontroller development, Bluetooth solutions, software and hardware custom development, APP development, small program development, WeChat official account development, etc. It can also undertake the design of intelligent electronic products, the development of living appliances, the research and development of beauty equipment, the application of Internet of things platform, the smart home control system, the development of TWS earphones, Bluetooth earphone speakers, the development of children's educational toys, the design of electronic education products, etc.