Design of Environmental Measuring Instrument Based on Single Chip Microcomputer

1 Introduction

With the improvement of people's living standards, various electronic products have developed by leaps and bounds, and electronic measuring instruments have gradually become richer and widely used in all walks of life. For example, in medicine, there are blood glucose meters and blood pressure meters; in physics, there are inductance meters, frequency meters, infrared meters, etc.; in the environment, there are a series of electronic measuring instruments such as air meters and noise meters. The original analog products have also gradually transformed into digitalization and integration, and are constantly moving towards humanization. Although there are many varieties of environmental measuring instruments at present, most of them can only display LCD and have no voice broadcast function. This paper introduces the design of a practical portable environmental parameter measuring instrument. The measuring instrument requires to give full play to the humanized characteristics, realize the broadcast of light and temperature, and give corresponding warm reminders. In order to meet the design requirements of the environmental measuring instrument, this design selects a streamlined 61 board with voice broadcast function based on Lingyang's SPCE061A chip as the core, which cooperates with the sensor module and uses the program to realize the measurement and broadcast functions.

2 Design ideas

This paper introduces the design of a practical portable environmental parameter measuring instrument, which can measure temperature and light brightness. This system uses 61 board as the control board, cooperates with the sensor module to measure the ambient temperature and light and broadcast the measured values ​​by voice. The hardware circuit consists of data acquisition module, SPCE061A, data storage module, keyboard input module, etc. The microcontroller software program mainly completes the functions of measurement, calculation, voice broadcast, etc. It adopts modular structure design and is implemented by C language and assembly language programming.

The environmental tester measures the temperature and light conditions of the environment through the voltage values ​​of the photoresistor and thermistor in the sensor module. These voltage values ​​are collected by the ADC module of SPCE061A. The key Key3 on the 61 board is mainly used to start the measurement of light and temperature. The measurement results are played through the speaker on the 61 board. Figure 1 is the design block diagram of the environmental measuring instrument.

Figure 1. Design block diagram of environmental measuring instrument

In the block diagram, the functions of each part and the devices used are:

(1) 61 board: The 61 board used in the control part of this design is the abbreviation of SPCE061A EMU BOARD. It is a streamlined development-simulation-experimental board with the Lingyang 16-bit microcontroller SPCE061A as the core. It is small in size and simple in structure. It is based on the SPCE061A chip, has a microphone and a speaker, and has rich voice playback functions.

The functions of several interfaces on the 61 board are:

① Input/output (I/O) interface: The 61 board leads out all 32 I/O ports of SPCE061A:

IOA0 ~IOA15, IOB0 ~IOB15. The corresponding SPCE061A pins are: Port A, 41~48, 53, 54~60; Port B, 5~1, 81~76, 68~64. And the I/O port is programmable, that is, it can be set as input or output.

② Audio input/output (I/O) interface: On the 61 board, X1 is the voice MIC input terminal, with automatic gain control (AGC), J3 is the voice output interface, a 2-pin pin external speaker, which is amplified by the voice integrated amplifier SPY0030A from the DAC output pin 21 or 22 and then output. It can work in the range of 2.4~6.0V, and the maximum output power can reach 700mW[1].

③Online debugger PROBE and EZ_PROBE interface: J4 is the interface of PROBE, which has 5 pins. It is used to connect PROBE to PC for debugging, simulation and program downloading; J11 is the interface of EZ_PROBE. A download line is used for program downloading. One end is connected to the 25-pin parallel port of PC and the other end is connected to the 5-pin EZ_PROBE interface of 61 board.

④Power interface: J10 is the power interface. The voltage requirement of the core SPCE061A of the 61 board is 3.3V, and the voltage of the I/O port can be selected as 3.3V or 5V. Therefore, the corresponding pins 15, 36 and 7 must be 3.3V, and the voltage of the I/O port 51, 52, 75 can be 3.3V or 5V. The choice of these two levels is selected by jumper J5.

(2) Sensor module: Another important device used in this design is the sensor module, which is also a product of Lingyang. It can measure temperature, measure light, detect obstacles, receive signals from the remote control, and simulate a simple remote control. In this design, the module operating voltage is set to: 3V~5.5V, and the operating temperature is set to 0℃~60℃. [page]

The following points should be noted when using the sensor module:

① When measuring temperature, what is measured is the temperature of the object (including air) in direct contact with the thermistor, and the thermistor has a certain reaction time; ② When measuring light, it is best to expose the entire photoresistor to the measurement environment; if you want to cover the light with your hand to measure whether the photoresistor is working normally, it is best to use your palm instead of your fingers, because some light will leak between your fingers; ③ The minimum operating voltage of the infrared receiving head is 3V; ④ The infrared transmission signal cannot maintain a high level for a long time, otherwise the infrared transmitting tube will be burned; ⑤ If an infrared transmitting and receiving tube is used to detect obstacles, the detection distance will shorten as the voltage decreases.

3 Software Design Flowchart

The software flow in this design is shown in Figure 2. In order to enable it to successfully complete the expected functions, flow charts are designed for the light measurement part, temperature measurement part, keyboard scanning part, voice playback part, A/D conversion part, etc. After debugging and running, each function is successfully realized.

4 Conclusion

This paper successfully realized the design of the environment measuring instrument by using the Antelope MCU and sensor module. The environment measuring instrument can measure the light and temperature and make voice broadcasts through the control of Key3. The ability to broadcast the results and give corresponding warm reminders is a major feature of this design. The environment measuring instrument can judge the current light intensity and measure the current temperature value through the domain value set in the program, and give corresponding warm reminders, so that users can understand the surrounding light intensity level and temperature value, and can make appropriate adjustments to the light and temperature in combination with warm reminders to make the environment more suitable for living and working. This has great practical significance for people who pay more and more attention to the quality of life, and only one Key3 key can obtain basic information about the surrounding environment, making the use of the environment measuring instrument relatively convenient and quick. At the same time, it also shows that with the continuous development of electronic technology, electronic measuring instruments will be more widely used in people's lives and work.