Development Of Time Interval Generator Based On AVR And FPGA

Mechanical stopwatch,electronic stopwatch,digital electric stopwatch,pointer electric stopwatch,digital millisecond meter this kind of instruments collectively known as time interval measuring instruments,applied in China's time frequency measurement field,often used to produce,record,measure,calibration time interval signals.Time interval generator is an instrument that can output one or more standard time interval signals to calibrate its technical indicators according to the calibration requirements of the measured time interval.In recent years,with the rapid development of time interval measuring instruments,most of the time interval generators developed according to the old calibration regulations in the market can no longer meet the demand for calibration,so it is necessary to develop a new type of time interval generators.The main work of this paper is as follows:?1?This paper according to the JJG237-2010 verification regulation of stopwatchs,JJG601-2003 verification regulation of time interval generator,JJG238-1995verification regulation of digital time interval measuring instrument,the analysis of the time test instrument,on the basis of technical requirements,determine the time of verification instrument features and performance indicators,formulated the research technical route,the system overall design of time interval generator based on AVR and FPGA was proposed.?2?Based on the principle of time interval generators circuit system,the control circuit is designed by using AVR microcontroller,and the time base circuit is designed by using constant temperature crystal oscillator,step-down transformer and hysteresis comparator.A high-precision time interval signal circuit is designed.Aiming at the measurement error caused by the mismatch between the time base of the pointer type electric stopwatch and the time verification instrument,a digital frequency multiplier with self-compensation function is designed by using the same frequency source method and FPGA technology.The simulation results show that the measurement error is effectively reduced.In order to solve the problem of the mainstream stopwatch fixture in the market,a kind of modular stopwatch fixture is designed?3?On the basis of analyzing the software function of time interval generators,the main program,serial communication,parallel communication,parameter setting and display control software modules are designed by using C language.At the same time,the instrument human-computer interaction interface is developed by using SDW display terminal design tool.?4?According to the national verification regulation time interval generator are tested for the functional and performance,the results show that this design time interval generator crystal oscillation circuit frequency accuracy up to 5×10^-9orders of magnitude,stopwatch measurement error reaches 1 ms orders of magnitude,Digital millisecond meter electrical measurement error reaches 1?s orders of magnitude,meet the demand of real time verification work,and the mainstream of the market at present time interval generator product contrast,some better performance indicators,reached the domestic advanced level.