Research And Design Of 5.5 Bit Digital Multimeter

Current, voltage, resistance, frequency, temperature, pressure, flow, flow rate and volume switches are commonly used in the production and life of the main accused of the parameters. Among them, the current, voltage, resistance and frequency is more and more important. In this way, as measured by the multimeter's status has become important, especially in high-precision multimeter is playing an extremely important role.In this paper, the main research and design a high-precision digital multimeter. Specific measurement method is the use of single-chip microcomputer system of collection and control signals. Single-chip microcomputer system includes the MSP430 processor, SPI interface, True RMS converter chip AD536, ADC AD7711, brown-out protection and reduction, as well as show circuit. The specific method is the use of analog circuits on a variety of electrical signals for data collection, through amplifier and filter circuit after the A / D conversion, the digital value after conversion into the single-chip microcomputer for data processing, at the same time displayed. Which software to use IAR compiler for C programming environment, using modular design methods, in order to achieve a variety of signal control algorithm module, data acquisition modules, dual-processor modules and the keyboard scan-line module. To measure the accuracy of the design for frequency measurement and the other three signals separately, the combination of MCU and CPLD design methods, and separated from low-frequency and high frequency measurements.Multimeter developed through the testing, measurement accuracy has reached a half 5 bit. Verification of the feasibility study and design. Intelligent instrument for future research provides a new design ideas and methods.