Electronic scale weighing system design, hx711 pressure sensor, 51 single chip microcomputer (proteus simulation, C program, schematic diagram, thesis and other complete data)

The design requirements
1. The system can realize the basic weighing function of the electronic scale （ The weighing range is 0～10Kg, The weight error shall not be greater than ±0.005Kg）;
2. The system shall have keyboard input function , Display weight , The function of calculating the total price ;
3. The unit of unit price and total price is yuan , The maximum amount is 999.99 element , The amount error shall not be greater than 0.01 element ;
4. The system is out of the maximum measurement range 10Kg when , With alarm indication function （ Buzzer 、LED Warning light ）;
5. The electronic scale is designed with both peeling function and weight calibration function ;

Design Overview
The electronic scale system is mainly composed of the minimum system of single chip microcomputer 、 data acquisition system 、 Human computer interface system 、 The alarm system consists of five parts .

The minimum system of single chip microcomputer mainly includes AT89C51 And classic reset circuit ; The data acquisition part consists of a load cell 、 Signal amplification and A/D The conversion part consists of , Signal amplification and A/D The conversion part is mainly composed of special-purpose high-precision 24 position AD Conversion chip HX711 Realization .

The human-computer interaction interface is keyboard input and dot matrix liquid crystal display , The main use of 4*4 Matrix keyboard and 1602 Liquid crystal display , It can input data conveniently and display data intuitively ; The alarm system consists of buzzer and LED The lamp consists of .

Simulation circuit diagram


Schematic diagram of electronic scale

Analysis of simulation results
open Proteus Simulation file , Its suffix is DSN. Double click the MCU , load main.hex file （ Position in ： MCU loading file ）; then , double-click HX711 chip , load HX711.hex file （ Position in ：HX711 Module load file ）.

Click on Proteus Run button in the lower left corner of the software , Run the simulation .LCD1602 Liquid crystal display (LCD) ：Welcom to Use Electronic Scale.

Then , After a prompt tone , Red LED The light is on ,LCD Display weight 、 Unit price and total price , All values are 0. here , The system is waiting for the goods to be weighed .

LCD According to the 3 The parameters are ：WE（Weight, Abbreviation for weight ）、PR（Price, Abbreviation for unit price ） and MONEY（ Indicates the total price ）.

Press down ‘ weight +’ or ‘ weight -’ key , Simulate cargo weighing , The weighing range is ：0~10Kg. If the weight is greater than 10Kg, Overweight alarm , The buzzer beeps , Red LED flashing ,LCD in WE Show ：-.–.


Enter the unit price through the matrix keyboard （PR）, The maximum input unit price is 99.9, You can enter a decimal point , The unit price is set to the nearest corner . Such as input 5.4 element , Enter the number key 5、 Dot keys and number keys 4 that will do .

Unit price input completed , Automatically display the total price （MONEY）, The total price is accurate to the decimal point 1 position ; The maximum total price is 999 element , Greater than this value ,LCD Show ‘-.–’ Indicates that the display range is exceeded .


This simulation design has calibration function , adopt ‘ calibration +’ and ‘ calibration -’ Two keys , It can be used in a small range （ Press down 1 Time , The weight display changes 0.001Kg） Calibrate the weight of the goods displayed on the scale . for example , Put the weight by 3.576Kg Calibrated as 3.574Kg.

After weighing the goods , Click on ‘ eliminate ’ key , Clear the unit price and total price , Click on ‘ peel ’ Key to clear the weight display , Note that the peeling key has the function of clearing the weight display ; Then you can weigh next time .

Simulate peeling function
First, press ‘ weight +’/‘ weight -’ key , Simulate the weight of a basket or box , When this weight is set , Press down ‘ peel ’ key , At this time, the weight display is cleared .

for example , Press down ‘ weight +’ key , Set basket weight 1.083Kg, And then click ‘ peel ’ key ,WE The display is cleared .


After peeling , Press again ‘ weight +’ Simulate the net weight of the goods 4.880Kg, then , Enter the unit price 3.0 element , The total price 14.06 element .

Press again ‘ peel ’ key , here WE Displays the net weight of the goods plus the weight of the basket , The total price also calculates the part of the basket , Press again ‘ peel ’ key , The weight is cleared .

part C Code

void main()
{
    
	init_eeprom();  // Start initializing the saved data 
	Init_LCD1602();									// initialization LCD1602
   EA = 0;
   Data_Init();
   Timer0_Init();
   // The beginning of junior high school , Disconnect 
   EA = 1;
	
// Get_Maopi();
	LCD1602_write_com(0x80);						// Pointer setting 
   LCD1602_write_word(" Welcome To Use ");	// 
   LCD1602_write_com(0x80+0x40);						// Pointer setting 
   LCD1602_write_word("Electronic Scale");
// Delay_ms(2000);
   Get_Maopi();
   LCD1602_write_com(0x80);						// Pointer setting 
   LCD1602_write_word("WE:0.000 PR:00.0");
   LCD1602_write_com(0x80+0x40);				// Pointer setting 
   LCD1602_write_word("MONEY: 0.00 ");
   Display_Price();
// Get_Maopi(); // Weigh the fur 

	while(1)
	{
    
// Every time 0.5 Weigh once a second 
	  if (FlagTest==1)
		{
    
			Get_Weight();
			FlagTest = 0;
		}			
	  	
	  keycode = Getkeyboard();
	  // Valid key values 0-15
	  if (keycode<16)
	  {
    
		 KeyPress(keycode);
		 Buzzer=0;
		 Delay_ms(100);
		 Buzzer=1;
		 while(keycode<16)
		 {
    
			if(keycode==12||keycode==13)
			{
    
				Buzzer=0;
				 Delay_ms(10);
				 Buzzer=1;
				 KeyPress(keycode);
				 Get_Weight();
				 flag_key=1;
			}
			keycode = Getkeyboard();
		 }
		 write_eeprom();			   // Save the data 
	  }
	}
}
//****************************************************
// Weigh 
//****************************************************
void Get_Weight()
{
    
	Weight_Shiwu = HX711_Read();
	Weight_Shiwu = Weight_Shiwu - Weight_Maopi;		// Get the net weight 
	
	Weight_Shiwu = (unsigned int)((float)Weight_Shiwu*10/GapValue)-qupi; 	// Calculate the actual weight of the object  
	if(Weight_Shiwu > 10000)		// Overweight alarm 
	{
    
		Buzzer = !Buzzer;	
		LED=!LED;
		LCD1602_write_com(0x83);
	   LCD1602_write_word("-.---");
	}
	else
	{
    
		if(Weight_Shiwu==0)
		LED=1;
		else if(Weight_Shiwu>0)
		LED=0; 
		Buzzer = 1;
		Display_Weight();
		money = Weight_Shiwu*price/1000;  //money In minutes 
	       // Show total amount 
	       Display_Money();
	}
}

//****************************************************
// Get fur weight 
//****************************************************
void Get_Maopi()
{
    
	unsigned char clear;
mm:	Weight_Maopi_0 = HX711_Read();
	for(clear=0;clear<10;clear++)
	{
    
		Buzzer=1;
		LED=1;
		Delay_ms(100);
		LED=0;
		Delay_ms(100);	
	}
	Weight_Maopi = HX711_Read();
	if(Weight_Maopi/GapValue!=Weight_Maopi_0/GapValue)
	goto mm;
	Buzzer=0;
	Delay_ms(500);
	Buzzer=1;
} 

The shared resources are
（1） be based on 51 SCM and HX711 The electronic scale system design of pressure sensor is completed, and the complete version of the paper is ;
（2）Proteus Simulation file ;
（3）Keil C Program files ;
（4）HX711 Module information ;
（5）Visio flow chart ;
（6） Schematic diagram of electronic scale ;
（7） List of electronic components ;
（8） Excellent literature translation ;

The full set of resources is as follows






Important things are to be repeated for 3 times ！

Important things are to be repeated for 3 times ！

Important things are to be repeated for 3 times ！

Get the graduation thesis of electronic scale design 、Proteus Simulation 、C Program 、 Schematic diagram 、Visio flow chart 、 List of components 、HX711 A complete set of information such as modules .

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