AC frequency meter using the PIC18F2550

This project shows an AC frequency meter using tow interrupts External interrupt and TMR0 interrupt.

Note: I can teach you or help you with yours Microcontroller or FPGA projects. If you interested contact me at: 

postgraduatecahg@gmail.com

int externals_tick = 0;  // for counting the external interrupts
float frequency = 0;
float T = 0;

// LCD pins confiuration
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RC0_bit;
sbit LCD_D5 at RC1_bit;
sbit LCD_D6 at RC2_bit;
sbit LCD_D7 at RC6_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;

sbit LCD_D4_Direction at TRISC0_bit;
sbit LCD_D5_Direction at TRISC1_bit;
sbit LCD_D6_Direction at TRISC2_bit;
sbit LCD_D7_Direction at TRISC6_bit;
// End LCD module connections

char txt[15];
char txt3[] = "frequency meter";
char txt4[] = "starting";


void interrupt() {

if(INTCON.TMR0IF)
{
  //PORTC.F0 = ~PORTC.F0;
  T = 32.768/externals_tick; // Tms
  frequency = (1/T)*1000;
  frequency =  frequency/2;
  FloatToStr(frequency, txt);
  INTCON.TMR0IF=0; // clear the TIMER0 interrupt
  TMR0L = 3; // this value is to perform ~32ms
  externals_tick = 0;
  T0CON.TMR0ON = 1;   // TMR0 is running now
}
else
{
    externals_tick++;
    INTCON.INT0IF=0; // clear the external interrupt
}

}

void main() {
 PORTC = 0;
 LATC = 0;
 TRISC = 0x00;

 ADCON1 = 0x0F;  // For digital configuration
 PORTB = 0;
 TRISB = 0xCF;

 Lcd_Init();                        // Initialize LCD

  Lcd_Cmd(_LCD_CLEAR);               // Clear display
  Lcd_Cmd(_LCD_CURSOR_OFF);          // Cursor off
  Lcd_Out(1,3,txt3);                 // Write text in first row
  Delay_ms(1000);
  Lcd_Cmd(_LCD_CLEAR);               // Clear display
  Delay_ms(100);
  INTCON.GIE = 1;  // global interrups are enable
  INTCON.PEIE = 1;  // pheriferical interrups.
  INTCON.INT0IE = 1; // external interrup enable
  INTCON.TMR0IE = 1; // TMR0 interrup enable

  INTCON2.INTEDG0 = 1; //1 = Interrupt on rising edge
  INTCON2.RBPU = 0;       //0= pull up
  INTCON2.TMR0IP = 1; //TMR0 Overflow Interrupt Priority bit

  T0CON.T08BIT = 1; //8 bits
  T0CON.T0CS = 0; //Timer0 Clock Source Select bit,
                 //0 = Internal instruction cycle clock (CLKO)
  T0CON.PSA = 0;  //0 = Timer0 prescaler is assigned.
                 // Timer0 clock input comes from prescaler output.
  T0CON.T0PS0 = 1; // Timer0 Prescaler Select bits
  T0CON.T0PS1 = 1; //
  T0CON.T0PS2 = 1; //
  TMR0L = 3;
  T0CON.TMR0ON = 1;   //start TMR0
  
     while(1){
     Lcd_Out(1,1,txt);
     delay_ms(100);
     }
}