[Zhejiang University of Science and Technology Electrical Competition] Low-frequency bi-phase function signal generator (Question F)

## This project won the first prize in the 5th Electronic Design Competition of Zhejiang Sci-Tech University

#### Team number: ZSTU

#### Team members: Lin Minghuang, Gao Hui, He Mengfan

#### Instructor: Lu Jun

## School-Level Electronic Design Competition" Design Summary Report

"Low-frequency Bi-Phase Sine Function Signal Generator"
outputs two independent sine waves, square waves, triangle waves, sawtooth waves, and modulated waves within a specific frequency range (programmable settings to generate signals Amplitude, frequency and phase difference); and display the frequency, amplitude and phase difference of the current two signal outputs on the LCD display, and display the waveform on the oscilloscope.
(1) The two signals are independent and can be programmed to output sine waves, square waves, triangle waves and sawtooth waves;

(2) The maximum amplitude of the two signal outputs is not less than 3V, the amplitude of each channel is independently programmable and adjustable, and the setting resolution is 100mv;

(3) The frequency range of the two signals is adjustable from 1000Hz to 2000Hz, the step value is 10Hz, the frequency accuracy is not less than 1%, and the frequency and step value of each signal are individually programmable and adjustable;

(4) Two frequencies are generated For the same sine signal, the phase difference can be set by program control, which can be changed from 0 to 360 degrees in steps of 10 degrees;

(5) The duty cycle of the generated square wave and sawtooth wave is adjustable in the range of 1% to 99%. The resolution is not less than 1%;

the play part

(1) the maximum amplitude of the two signal outputs is not less than 6V, the amplitude of each channel is independently programmable and adjustable, and the set resolution is not less than 10mv;

(2) the frequency step of the two sinusoidal signals The value is not greater than 1Hz, and the frequency accuracy is not less than 0.1%;

(3) The phase difference setting resolution of two sinusoidal signals with the same frequency is not greater than 3 degrees;

(4) Generate analog amplitude modulation (AM) signal: 100KHz ~1MHz The modulation degree ma within the range can be programmed between 10% and 100%, with a step of 10% and a sinusoidal modulation signal frequency of 100Hz;

(5) Generate analog frequency modulation (FM) signal: generated in the frequency range of 10KHz~1MHz 1KHz maximum frequency deviation. And the maximum frequency deviation can be divided into two-level program-controlled adjustment of 500Hz/1KHz, and the sinusoidal modulation signal is 100Hz;

(6) Pattern output: It can display patterns on the oscilloscope, such as displaying simple letter symbols such as W, V, L, N, etc.

Plan: Use stm32 digital implementation, use function design method, analyze the functional expression of each waveform within one cycle and analyze each sampling point, store the results in the array, set the frequency, and always accurately control it to the external D/A. The waveform is amplified through an amplification circuit, which can achieve high-precision program control. The waveform accuracy depends on the data accuracy in the function and the D/A conversion speed of the microcontroller. STM32 digital waveforms are used to generate waveforms, and a 2.4-inch LCD resistive touch screen is used for the control and display interface.
The low-frequency bi-phase sine signal generator system is mainly composed of CPU, timer, two 12-bit DAC converters, amplifier circuit, amplitude modulation circuit, frequency modulation circuit, power supply and other circuits: the main control chip is STM32. The overall block diagram of the system is as follows:

![Picture 2.png] Please see the attached report for other details