Speed measurement based on 51 single chip microcomputer and Hall sensor

1. Introduction to small projects

Mainly adopts stc89c51/52 Single chip microcomputer as the main controller , The hall sensor is used as the basic module of speed measurement , Use the key to control the speed , The nixie tube displays the current speed .

The final finished product is shown as follows ：

2. Power part

1. The power supplied by the power supply should be as large as possible , I'm powered by Rolex power bank （5V,2.1A outlet ）. Because the power supply is too small , The motor will not be able to drive , Or digital tube flashing and other hardware bug.
2. If the voltage of the power supply is higher than 5V, A voltage stabilizing circuit needs to be used at the power input , Stabilize the input voltage to 5V To MCU , And other peripherals . Prevent device damage caused by high voltage .

3. hardware component

1. stc89c51/52 The smallest system of

Be careful ： If you use the general USB Interface power supply , When the motor rotates , The pin power supply of MCU may be unstable , Therefore, it is necessary to use the single chip microcomputer IO External pull-up and drain resistance .P3 You don't need to .
9 Needle drainage resistance is as follows ： The smaller end is the common end , Need and power 5V Connect , The other ports are welded with the pins of the single chip microcomputer one by one .

2. Hall sensor

Pay attention to the pins , On the narrow side, the pin sequence ：

there VOUT The port can be directly connected to the external interrupt of the single chip microcomputer 1 mouth , It can pass through a voltage comparator lm393 Something like that is giving the MCU .

3. DC motor drive
51 Single chip microcomputer IO The output current of the port is too small , The effect of driving DC motor is not obvious , Can't reach the later speed change , Need to use a triode （9015\9013 This kind can ） The amplifier circuit drives the motor ： The demonstration circuit is as follows ：（ The resistance shall be modified according to their own needs ）

4. Common cathode nixie tube

 // Digital tube position selection 
sbit S1=P2^4;	 
sbit S2=P2^5;   
sbit S3=P2^6;	 
sbit S4=P2^7;  

// Digital tube segment selection ：P1 Eight of IO mouth . When connecting, be sure to select according to the segment shown in the following figure （ Pay attention to pay attention to ： Easy to connect wrong ）

4. Software part

1. Overall drawing of software engineering ：

2.main.c File code ：
Create your own 51 Single chip microcomputer keil Engineering documents , Copy the following code to your project file main.c Just replace the file

/************************************************************************************** *  be based on 51 Single chip microcomputer speed measurement  *  Realization phenomenon ： Press the button K1 Slow down   Press the button K2 Speed up   External interrupt 1 Corresponding IO mouth P3^3  matters needing attention ： The motor speed shall not be too fast , Otherwise, the nixie tube display will be unstable  ***************************************************************************************/

#include "reg52.h" // This file defines some special function registers of MCU 


typedef unsigned int u16;	  // Declare and define data types 
typedef unsigned char u8;

// Test port （ Decide according to your own needs ）
sbit led=P0^0;	   // The of single chip microcomputer P0.0 The port is defined as led

/************************************************************************************** **************************** The core part of the ************************************************* ***************************************************************************************/
// Duty cycle 
u16 time = 0;  //  Variable that defines the duty cycle 
u16 count=30;  // Define the upper duty cycle limit 
sbit PWM=P0^1;// P0.1 Output pwm

// Speed 
u16 zhuansu=0;   // The initial value of speed is 0
u16 jishu = 0;   //jishu The initial value of the variable is 0
u8 flag = 0;     // Timer 1 Count variables 
// Key 
sbit k1=P2^0;	 
sbit k2=P2^1;   
sbit k3=P2^2;	 
sbit k4=P2^3;  

// Digital tube position selection 
sbit S1=P2^4;	 
sbit S2=P2^5;   
sbit S3=P2^6;	 
sbit S4=P2^7;  

// Digital tube position selection ：P1 Eight of IO mouth 

// Common cathode nixie tube segment selection 
u8 code smgduan[]={
    0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
					0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};// Show 0~F Value 

// The nixie tube stores intermediate variables 
unsigned char Display_data[4];
/******************************************************************************* *  Letter   Count   name  : delay *  The functionality  :  The time delay function ,i=1 when , About time delay 10us *******************************************************************************/
void delay(u16 i)
{
    
	while(i--);	
}


// Timer and external interrupt 1 Initialization function for 
void InitSyetem()
{
    	
	
	// Configure external interrupts 1： Collect the falling edge triggered by Hall sensor 
	IT1 = 1;      // Select the falling edge trigger 
	EX1 = 1;      // Open external interrupt 1 
	
	// Timer 0,1 Operation mode 1
	TMOD=0x11; // Timing or counting mode control register 
	// Timer 0 To configure ： produce PWM wave 
	TH0=(65536-10)/256;// When the initial value is given 10us
	TL0=(65536-10)%256;//s
	ET0=1;// Turn on the timer 0 interrupt 
	TR0=1;// Start timer 0 
	
	// timing 1： velocity measurement 
	TH1=(65536-10000)/256;// When the initial value is given 10ms
	TL1=(65536-10000)%256;
	ET1=1;// Turn on the timer 0 interrupt 
	TR1=1;// Start timer 0 
	
	PX1=1;// set priority 
	PT1=1;// Set timer 1 Is the highest priority 
	EA=1;// General interruption 
}

// external 1 Interrupt service function 
void Service_Int1() interrupt 2
{
    
    jishu++;    // Hall's falling edge counts the number of times at a time 
	  if(jishu == 100)  // The cumulative count has 100 Time , The total time is 100 * 10ms = 1s
		{
    
			led^=led;   //led flashing 
		}
}


// timing 0 The processing function generates PWM  Speed regulation principle ——— stay PWM Drive the motor to rotate at high level   stay PWM Stop the motor at low level 
void Service_Timer0() interrupt 1
{
    
	TR0=0;// When assigning initial value , off timer 
	TH0=(65536-10)/256;// When the initial value is given 
	TL0=(65536-10)%256;//0.01ms
	TR0=1;
	
	time++;   // Count variables 
	if(time>=100) time= 0;  // Clear flag variable 
	if(time<=count)  // Less than the set value , Output high level 
	{
    
		PWM = 1;
	}
	else
		PWM = 0;
}

// Timer 1 Interrupt processing displays the speed 
void Service_Timer1() interrupt 3				 
{
    
	TR1=0;// When assigning initial value , off timer  
  TH1=(65536 - 10000) / 256;
  TL1=(65536 - 10000) % 256;// timing 10ms
	TR1=1;
  flag++;  	      // Count variable plus  
  if(flag==100)		// Time to arrive 1s  Measure the speed at this time 
  {
    
// led=~led; //led State inversion 
			zhuansu = jishu;   // Monitor the total number of counts of the hall sensor  
			jishu=0;					// Speed setting 0
			flag=0;           // Clear count variable 
	}
}

// Nixie tube processing function 
void Deal_data()
{
    
	 Display_data[3]=smgduan[zhuansu/1000];  // High digital tube 
	 Display_data[2]=smgduan[zhuansu/100%10];// Go to second 
	 Display_data[1]=smgduan[zhuansu/10%10];
	 Display_data[0]=smgduan[zhuansu%10];    // Nixie tube low position 
}

/******************************************************************************* *  Letter   Count   name  : DigDisplay *  The functionality  :  Digital tube dynamic scanning function , Circular scanning 4 A digital tube display  ****************************************************** *************************/
void DigDisplay()
{
    
	u8 i;	
	for(i=0;i<4;i++)
	{
    
		switch(i)	 // Biting , Choose the LED that lights up ,
		{
    
			case 0 : S1 = 0; S2 = 1; S3 = 1; S4 = 1;break;  // Light up the first digital tube 
			case 1 : S2 = 0; S1 = 1; S3 = 1; S4 = 1;break;
			case 2 : S3 = 0; S1 = 1; S2 = 1; S4 = 1;break;
			case 3 : S4 = 0; S1 = 1; S2 = 1; S3 = 1;break;			
		}
		P1=Display_data[i];// Send segment code 
		delay(5); // Scan at intervals   The less time , Light up together and the more stable the display ; The more time , It's running water that lights up 
		P1=0x00;// Blanking   When time is too fast , Each nixie tube will have ghosting 
	}
}


/******************************************************************************* *  Letter   Count   name  : keypros *  The functionality  :  Key handling functions , Judge button K1 Whether to press  *******************************************************************************/
void keypros()
{
    
	if(k1==0)		  // Test button K1 Whether to press 
	{
    	
		delay(100);   // Eliminate jitter   It's about 10ms  Estimation of time 100*n=1(s)
		if(k1==0)	 // Judge whether the key is pressed again 
		{
    
			led=~led;	  //led State inversion 
			count+=10;
			if(count >= 90)  // Set an upper limit 
			count+=90;
		}
		while(!k1);	 // Check whether the key is released   If it is false, it means that the key is not released 
	}	
	if(k2==0)		  // Test button K1 Whether to press 
	{
    	
		delay(100);   // Eliminate jitter   It's about 10ms
		if(k2==0)	 // Judge whether the key is pressed again 
		{
    
			led=~led;	  //led State inversion 
			count-=10;
			if(count <= 10)
			{
    
				count = 10;
			}
		}
		while(!k2);	 // Check whether the key is released 
	}	

}

/******************************************************************************* *  Letter   Count   name  : main *  The functionality  :  The main function  *  transport   Enter into  :  nothing  *  transport   Out  :  nothing  *******************************************************************************/
void main()
{
    
  	led = 0;     // Power on and turn off the small light 
	P1 = 0x00;   // Power on initialization and turn off the nixie tube 
  	InitSyetem();// Timer and external interrupt 1 Initialization function for 
	while(1)
	{
    
		keypros();   // Key handling functions 
		Deal_data(); // Data processing functions 
		DigDisplay(); // Nixie tube display function 
	}		
}