DC MOTOR SPEED SENSOR (RPM DETECTOR) USING 8051 MICROCONTROLLER

CALCULATIION:

• 11.0592 crystal frequency
• Microcontroller takes 12 machine cycles for execution one function.
• 1 machine cycle time = 11.0592/12 = 0.9216 Mhz
• Time= 1/0.9216 Mhz = 1.085 uS
• So when timer counts from 0000H to FFFFH (65535 counts) it take                                                 => 1.085 uS X 65535 = 0.071105 seconds

• So for a dealay of 5 seconds we should give a count value                                                               => 5 sec / 0.071105 seconds = 70.3185 
• For 10 sec delay = 10 sec/ 0.071105

CODE:


#include<reg51.h>
#include<string.h>
#include<stdio.h>
#define LCD_clear() LCD_command(0x01) // Clear LCD Display
#define LCD_orgin()LCD_command(0x02) //set to orgin LCD
#define LCD_row1() LCD_command(0x80) // Begin at 1st line
#define LCD_row2()LCD_command(0xc0) // Begin at 2nd line


sbit port10=P1^7;       //IR Sensor Input
sbit rs=P1^0;             //Lcd Register Select Pin
sbit en=P1^2;           //Lcd Enable Pin

void lcd_en()      //Funtion for LCD Enable
 {
   en=1;
   en=0;
}

void LCD_delay(unsigned char ms) //Function for create Time Delay
{
 unsigned int n,i;
for(n=0;n<ms;n++)
  {
   for(i=0;i<100;i++);
  }
}

void LCD_command(unsigned char command) //LCD Command Pass Funtion
 {
  rs=0;
  P0=command;
  lcd_en();
  LCD_delay(1);
}
void LCD_init() //LCD intialization funtion
{
 LCD_command(0x38);
 LCD_command(0x06);
 LCD_command(0x0c);
 LCD_command(0x01);
}
void LCD_putc(unsigned char ascii)
 {
  rs=1;
  P0=ascii;
  lcd_en();
  LCD_delay(2);
}
void LCD_puts(unsigned char *lcd_string)
 {
  while(*lcd_string)
    {
     LCD_putc(*lcd_string++);
   }
}
void disp(unsigned char name1)
  {
    rs=1;
    P0=name1;
    lcd_en();
    LCD_delay(300);
 }
void main()
 {
  int cnt=0;
  port10=0;   //make P1.0 as init=0, initially all port pins are high
 
  LCD_init(); //call LCD initialization function
  LCD_command(0x80); //LCD command for display 1st line
  LCD_puts("By-krishnaraj"); 
  LCD_command(0xc0); //LCD command for display secondline
  LCD_puts("RPM="); //String display in the LCD
  disp(((cnt%10000)/1000)+48);
  disp(((cnt%1000)/100)+48);
  disp(((cnt%100)/10)+48);
  disp(((cnt%10)/1)+48); 

  
while(1)                  //Run forever always true
  {
        
if(port10==1)    //check condition P2.0 is high P2.0==1
     {
      
        while(port10==1)
        {     ;}
         cnt=cnt+1;
        LCD_command(0xc0); //LCD command for display second line
        LCD_puts("RPM="); //String display in the LCD
        disp(((cnt%10000)/1000)+48);
        disp(((cnt%1000)/100)+48);
        disp(((cnt%100)/10)+48);
        disp(((cnt%10)/1)+48); 
        
     }
       
   
}
}




Working Tested ok: