3 channel frequency counter

[priyal101]

Hi, I am required to make a 3 channel frequency counter for my project. I am using a PIC18F4550. I am a begineer at PIC and I found a single channel code in one of the books I was reading. I am having problem with the timers(falling short on them). Can anyone help me modify it to 3 channel?


This is the single channel code

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//LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
//end LCD module connections

#define PULSE PORTA.RA4

unsigned int Overflow;
unsigned char Cnt;
//
//Timer interupt service routine jumps here at every 10ms
//
void interrupt(void)
{
 if(INTCON.TMR0IF==1)            //If TIMER0 INTERRUPT
            {
                  Overflow++;     //Increment Overflow flag
                  INTCON.TMR0IF=0; //Clear timer0 interrupt flag
            }
 if(PIR1.TMR1IF==1)                //If timer1 interrupt
            {
                   TMR1H=0x0B;     //Reload timer register
                   TMR1L=0xDC;
                   Cnt++;          //Increment cnt
                   PIR1.TMR1IF=0;  //Clear Timer1 interrupt flag
            }
}



void main()
{
 unsigned char Txt[11];
 unsigned long Elapsed;
 unsigned char L_Byte, H_Byte;

 ANSELA = 0; // Configure PORTA as digital
 ANSELB = 0;
 TRISA.RA4 = 1; // RA4 is input
 Lcd_Init(); // Inialize LCD
 Lcd_Cmd(_LCD_CURSOR_OFF); // Disable cursor
//
 // Configure TIMER0 for 16-bit mode, no prescaler, clock provided by external
 // signal into pin T0CKI. Timer is not started here
 //
 T0CON = 0x28; // TIMER0 16-bit,no prescaler,T0CKI clk
//
// Configure Timer1 for 250 ms Overflow. Timer1 is not started here
//
 T1CON = 0x36;

 PIE1 = 0x01; // Enable TIMER1 interrupts
 PIR1.TMR1IF = 0; // Clear TIMER1 interrupt flag
 INTCON = 0xE0; // Enable TIMER0 and TIMER1 interrupts

 for(;;) // Wait for interrupts
 {
 TMR0H = 0; // Clear Timer0 registers
 TMR0L = 0;
 TMR1H = 0x0B; // Load Timer1 registers
 TMR1L = 0xDC;
 //
 Overflow = 0; // Clear Overflow count
 Cnt = 0; // Clear Cnt
 //
  // Start TIMER0. It will increment each me an external pulse is detected.
 // TIMER0 increments on the rising edge of the external clock
 //
 T0CON.TMR0ON = 1;
 //
 // Start Timer1 to count 4 × 250 ms = 1 s
 //
 T1CON.TMR1ON = 1;
 while(Cnt != 4); // Wait unl 1 s has elapsed
 //
 // 1 s has elapsed. Stop both mers
 //
 T0CON.TMR0ON = 0; // Stop TIMER0
 T1CON.TMR1ON = 0; // Stop Timer1
 // Get TIMER0 count
 L_Byte = TMR0L;
 H_Byte = TMR0H;
 //
 // Store TIMER0 count is variable Elapsed
 //
 Elapsed = (unsigned long)256 * H_Byte + L_Byte;
 Elapsed = 65536 * Overflow + Elapsed;
 //
 // Convert into string and display
 //
 LongWordToStr(Elapsed, Txt); // Long to string conversion
 Lcd_Cmd(_LCD_CLEAR); // Clear LCD
 Lcd_Out(1,1,"Frequency (HZ)"); // Display heading
 Lcd_Out(2,1,Txt); // Display measured frequency

 Delay_ms(1000); // Wait 1 s and repeat
 }
}

[jayanthd]

My project is here. You can refer it. I am pic.programmer there.

https://www.edaboard.com/showthread.php ... Tachometer

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Elapsed = (unsigned long)256 * H_Byte + L_Byte;

will be slower to compute.

Try

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Elapsed = (unsigned long)H_Byte << 8 + L_Byte;

Edit:

Another thing...

In Lcd sbit defines you should replace

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RB4_bit;

and other similar with LATx registers as you are using PIC18F otherwise you will get garbage or no display.