Low Frequency Signal Measuring Device Based on STM32F103
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This paper presents a new method of frequency measurement, which does not need complex hardware circuit, and realizes the measurement of signal frequency with the method of pure software. Triangle wave, sine wave, square wave, trapezoid wave and other signals (the highest voltage value is within 5V) can be directly input to the high-performance embedded microprocessor stm32f103zet6 for DMA + A / D acquisition, which can continuously acquire 500 points at a time. The data of 500 points can be processed by software to get the maximum and minimum values, calculate the slope, and judge the input waveform. Because DMA mode can achieve high-speed, mass data transmission, and the acquisition time between each point is fixed, so by counting the number of points between the two maximum values, the cycle and frequency can be obtained. For square wave signal, the duty cycle can be calculated by counting the high and low level data in a cycle. Compared with the traditional measurement method, this method has a simple interface circuit, which can realize the acquisition of low-frequency signal and the calculation of frequency, period, and duty cycle and peak value.
DMAl; ADC; Low-Frequency Signal