AT89C52 MCU frequency meter (1Hz ~ 20MHz) design, LCD1602 display, including simulation, schematic diagram, PCB and code, etc

The design requirements
1. With MCS-51 Series single chip microcomputer is the control device , use C Language for program development , Combined with peripheral electronic circuits , Design a digital frequency meter ;

2. Can be right 1HZ～20MHZ Sine wave 、 Triangle wave 、 The frequency of periodic signals such as square wave signal is measured ;

3. Measurement error ： lower than 0.1%;

4. The frequency measurement results are LCD1602 Liquid crystal display (LCD) ;

System Overview
This design gives a method to AT89C52 The design scheme of digital frequency meter with single chip microcomputer as the control core . The plan is made up of 6 Component composition , They are power modules 、 Minimum system of single chip microcomputer 、 Signal amplification module 、 Shaping module 、 Frequency division module and display module .

Working principle is ： The power module provides stable power supply for the whole system 5V Working voltage , The user inputs a periodic signal through the signal source , The input signal is amplified by triode circuit and shaped by Schmidt trigger , Become a square wave that can be recognized by single chip microcomputer , Complete the square wave division circuit 100 Double the frequency .

When the frequency of the input signal is lower than 200KHZ when , The single chip microcomputer directly reads and calculates the unit time before frequency division (1S) Number of signal pulses collected in , Is the signal frequency ;

When the frequency of the input signal exceeds 200KHZ when , The single chip microcomputer reads and calculates the number of signal pulses after frequency division , Then it is converted into the actual frequency through data processing .

Last , The single chip microcomputer outputs the frequency measurement value to LCD1602 Real time display on the display .

Simulation circuit diagram


Schematic diagram

PCB chart

Physical drawing of frequency meter

Analysis of simulation results
open Proteus Simulation file , File suffix DSN. Double click the MCU , load Program.hex file （ be located C In the program folder ）, Run the simulation , The results are shown below , The frequency of the measured signal is 13HZ.

Simulation runtime , Will pop up VSMCounter Timer and VSM Signal Generator Two windows ,VSM Counter Timer Used to display the standard frequency .

In the simulation , When the measured signal voltage is greater than 5V when ,VSM Counter Timer To work properly . It doesn't mean that , In the physical test of the actual frequency meter , The measured signal source voltage shall be greater than 5V Talent .

actually , The measured signal voltage is in tens of mV, You can also check the display on the oscilloscope , It does not affect the measurement of frequency , This is just the limitation of simulation .

VSM Signal Generator Used to adjust the frequency of the measured signal , It has four knobs , Their functions and uses are shown in the table below .

In the simulation , Mainly regulate Centre and Frequency knob , After setting the frequency gear , turn Centre The knob changes the frequency ,LCD1602 The display will follow the display .

When the measured signal frequency is 390HZ、5.6KHZ and 19063HZ when , The simulation results are as follows .



When the measured signal frequency is 19063HZ, The measurement result is 19051HZ, The frequency measurement error is calculated as ：

The frequency of the measured signal is tens of 、 A few hundred HZ when , The frequency can be measured quickly ; When the frequency reaches KHZ when , Due to the limited computing performance of single chip microcomputer , It may take a few minutes to get the simulation results .

When the frequency reaches MHZ When above , For example, the frequency of the measured signal is set to 1.17MHZ when , Single chip microcomputer operation cost 12 About minutes , To calculate the frequency value . The operation process is as follows , The figure below 1 Because the single chip microcomputer is in the process of operation , The measurement results have not been obtained ; chart 2 by 1.17MHZ Set frequency of , The result measured by single chip microcomputer is 1169700HZ.


The frequency measurement error is calculated as ：

in summary , The frequency meter simulation design meets the range requirements 、 Error and other requirements .

Resource content

（1） be based on 51 MCU digital frequency meter design paper complete version ;

（2）C Program ;

（3）Proteus Simulation ;

（4） Schematic diagram and PCB file ;

（5）Visio Flow chart file ;

（6） List of components ;

（7） Translation of English documents ;

（8） References and Literature ;

Resource screenshot







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