Abstract :The multi-meter presented here is based on a microprocessor (80C51).All components used are low-cost, high-speed CMOS type. The instantaneous values of the voltage and current can be sampled simulate amorously by two sample-and-hold circuits. The sampled analog signal that can be processed by CPU. The PLD is used for address decoding and logic signal converting. For accuracy calculation .50 points are sampled in a power cycle. The sampling intervals are decided by the measured power frequency.Then,the voltage and current rms valves.active power and reactive power and reactive power are calculated. A 4-place seven-segment LED is used to display the results.The function of the multi-meter can be selected by a keypad.Besides,the functions of the multi-meter can be extended,such as measure ments of frequency,phase,maximum and minimum values of current,voltage,active power and reactive power,and rms values of harmonic voltage.
Design branch three modules: Data acquisition 、Data handling and display module. The data signal adopts the programmable to operate amplifier PGA103, To great 、Separately is enlarged the handle to the little signal, The sampling control signal is carried on 64 -fold of frequencies coming into being through integration PLL ADC0809 to fathoms the signal; The data handling takes onboard computer 80C51 as the core, Accurately dominate and rigorously enforce calculation to collecting the signal; Display section but 74LS164's dislocation register and the nixie light constitutes.
Keywords: figure style workman frequency virtual value; 80C51 signal chip computer;data collect;data processing;display module