microcontroller 1

 Calculator using Pic16f877 microcontroller

Pic16f877 microcontroller calculator - Project requirements

• Pic16f877 Microcontroller
• 16x2 lcd 
• 4x4 keypad
• Crystal 20 MHz
• Potentiometer/variable resistor (For setting Lcd Contrast)
• Bread board or PCB for Circuit Designing
• Power Supply

Project Code

#include< htc.h>
#define _XTAL_FREQ 20e6
#define rs RD6
#define en RD7
#define r0 RC0
#define r1 RC1
#define r2 RC2
#define r3 RC3
#define c0 RC4
#define c1 RC5
#define c2 RC6
#define c3 RC7

void lcdcmd  (unsigned char);
void lcddata (unsigned char);
void disp_num(float num);
int get_num  (char ch);
void lcdinit ();
char scan_key(void);

unsigned char  s[]={"ENTER 1 NO= "};
unsigned char s1[]={"ENTER 2 NO= "};
unsigned char s2[]={"OPERATOR = "};
unsigned char s3[]={"***RESULT***"};

void lcdinit(){
 __delay_ms(400); lcdcmd(0x30); __delay_ms(400); lcdcmd(0x30);
__delay_ms(400); lcdcmd(0x30); __delay_ms(400); lcdcmd(0x38);
    lcdcmd(0x0F); lcdcmd(0x01); lcdcmd(0x06); lcdcmd(0x80);
}

void main (void)
  {
    TRISC=0xF0;        //Rows Output, Coulombs Input
    TRISB=0x00;        //Port-B as Output
    TRISD6=0;          //Port-D PIN-6 as Output
    TRISD7=0;          //Port-D PIN-7 as Output
    __delay_ms(400);
  
   unsigned int count=0;
   int k2,k1; 
   char ke,key,key1;
   lcdinit();        //Initializing Lcd

 while(1){   
      while(s[count]!='\0')     //Displaying String s on LCD
      {
        lcddata(s[count]);
        count++;
      }

ke=scan_key();   //Scan the First Digit
k2=get_num(ke);  //Converting Char into number
lcdcmd(0x01);    //Clear Lcd
count=0;

while(s2[count]!='\0')    //Displaying String s2 on LCD
{
lcddata(s2[count]);
count++;
}

key=scan_key();  //Scaning operator
lcdcmd(0x01);    //Cleat Lcd
count=0;

while(s1[count]!='\0')  //Displaying String s1 on LCD
{
lcddata(s1[count]);
count++;
}

key1=scan_key();  //Scan Second digit
k1=get_num(key1); //Converting Char into number
lcdcmd(0x01);     //Clear Lcd
lcdcmd(0x82);     //Start displying data on lcd at position Row=1 Coulomb=3
count=0;

while(s3[count]!='\0')  //Displaying String s3 on LCD
{
lcddata(s3[count]);
count++;
}
count=0;
lcdcmd(0xC0);   //Jump to second Line of Lcd
lcddata(ke);
lcddata(key);
lcddata(key1);
lcddata(' ');
lcddata('=');

switch(key)
{
case '+':
disp_num(k1+k2);
break;
case '-':
disp_num(k2-k1);
break;
case '*':
disp_num(k2*k1);
break;
case '/':
disp_num((float)k2/k1);
break;
}
}
}

void lcdcmd(unsigned char value)  //Sending Commands to Lcd
  {
    PORTB = value;      
    rs = 0;
    en = 1;            
    __delay_ms(100);
    en = 0;
    __delay_ms(100);    
  }
void lcddata(unsigned char value) //Sending Data to Lcd
  {
    PORTB = value;  
    rs = 1;
    en = 1;          
    __delay_ms(100);
    en = 0;
    __delay_ms(100);
  }
  


char scan_key()      //Scan the Pressed Key by user 
{
unsigned char c='s';
while(c!='a')
{
r0=0;r1=1;r2=1;r3=1;
if(c0==1 && r0==0){ lcddata('7');__delay_ms(500);return '7';c='a';}
if(c1==1 && r0==0){ lcddata('8');__delay_ms(500);return '8';c='a';}
if(c2==1 && r0==0){ lcddata('9');__delay_ms(500);return '9';c='a';}
if(c3==1 && r0==0){ lcddata('/');__delay_ms(500);return '/';c='a';}
r0=1;r1=0;r2=1;r3=1;
if(c0==1 && r1==0){ lcddata('4');__delay_ms(500);return '4';c='a';}
if(c1==1 && r1==0){ lcddata('5');__delay_ms(500);return '5';c='a';}
if(c2==1 && r1==0){ lcddata('6');__delay_ms(500);return '6';c='a';}
if(c3==1 && r1==0){ lcddata('*');__delay_ms(500);return '*';c='a';}
r0=1;r1=1;r2=0;r3=1;
if(c0==1 && r2==0){ lcddata('1');__delay_ms(500);return '1';c='a';}
if(c1==1 && r2==0){ lcddata('2');__delay_ms(500);return '2';c='a';}
if(c2==1 && r2==0){ lcddata('3');__delay_ms(500);return '3';c='a';}
if(c3==1 && r2==0){ lcddata('-');__delay_ms(500);return '-';c='a';}
r0=1;r1=1;r2=1;r3=0;
if(c1==1 && r3==0){ lcddata('0');__delay_ms(500);return '0';c='a';}
if(c3==1 && r3==0){ lcddata('+');__delay_ms(500);return '+';c='a';}
}
return 0;
}

int get_num(char ch)         //converting character into integer
{
switch(ch)
{
case '0': return 0; break;
case '1': return 1; break;
case '2': return 2; break;
case '3': return 3; break;
case '4': return 4; break;
case '5': return 5; break;
case '6': return 6; break;
case '7': return 7; break;
case '8': return 8; break;
case '9': return 9; break;
}
return 0;
}

void disp_num(float num)            //Displays calculated value on LCD
{
unsigned char UnitDigit  = 0;  //Contains unit digit of calculated value
unsigned char TenthDigit = 0;  //contains 10th digit of calculated value
unsigned char decimal = 0;
int j,numb;

j=(int)(num*10);
numb=(int)num;

if(numb<0)
{
numb = -1*numb;  // Make number positive
lcddata('-'); // Display a negative sign on LCD
}

TenthDigit = (numb/10);         // Findout Tenth Digit

if( TenthDigit != 0)         // If it is zero, then don't display
lcddata(TenthDigit+0x30); // Make Char of TenthDigit and then display it on LCD

UnitDigit = numb - (TenthDigit*10);

lcddata(UnitDigit+0x30); // Make Char of UnitDigit and then display it on LCD
lcddata('.');
decimal=(j%10)+0x30;             //Display If any value after Decimal Point
lcddata(decimal);
__delay_ms(3000);
lcdcmd(0x01);
}