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proplem with digits

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L

lakis

New Member
Hi guys. After long time I managed to count the period and the high time of a rectangular waveform .
My problem now is that although the period and the high Time are display ok in the screen when I try to calculate the duty cycle (dutycycle = (Thigh *100)/period (the 100 is to get a 2 digit integer) ) I have the following .

If high time is until 330 -350μs I get the first two digits as I suppose to .
If the high time is greater than 350 μs I get a screen full of numbers and unknown symbols.

this is my code
Code: 
#include<p18f452.h>
#include<xlcd.h>// Include function definitions for the External LCD Library library
#include<delays.h>// Include function definitions for built in Delay routines
#include <stdio.h>
#include <timers.h>
#include <capture.h>
#include <stdlib.h> /**********tin aferesa epeidi ekane problima sto itoa. Kanonika auti einai bibliothiki poy exei to idoa mesa tin ebala otan ebla ton ADC kodika Den ipirxe prin. Douleue sosta xvris ayti*/

#include <math.h>

#pragma config LVP=OFF
#pragma config OSC=HS
#pragma config WDT=OFF// Use internal Oscillator, Watchdog off, LVP off
#pragma config DEBUG=ON

 






void DelaySTRING(void);
void main(void)
{




	int i,z,t,x;
 unsigned    int period,per1; // unsigned
unsigned int total;
 unsigned int thigh;
unsigned int th;
float dutycycle;
int dekadikos;
int c2=22;
 float y,c1;

char str[5];

	unsigned char newlineadd=0x40; // Line 2 addresses are 40h to 4Fh
    
	ADCON1=0X7F;//Make all ports Digital	

	
	while( BusyXLCD());// Wait till LCD finishes executing command
TRISCbits.TRISC2 = 1; /* configure CCP1 pin for input */
T3CON = 0x81; /* use Timer1 as the time base for CCP1 capture */
PIE1bits.CCP1IE = 0; /* disable CCP1 capture interrupt */
PIR1bits.CCP1IF = 0; /* clear the CCP1IF flag */
T1CON = 0x81; /* enable 16-bit Timer1, prescaler set to 1 */
CCP1CON = 0x05; /* capture on every rising edge */
while (!(PIR1bits.CCP1IF)); /* wait for 1st rising edge */
PIR1bits.CCP1IF = 0;
per1 = CCPR1; /* save the first edge (CCPR1 is accessed as a 16-bit value) */
PIE1bits.CCP1IE = 0;
CCP1CON = 0x04;
while (!(PIR1bits.CCP1IF)); /* wait for the 2nd rising edge */
PIR1bits.CCP1IF = 0;
thigh=CCPR1;
PIE1bits.CCP1IE = 0;
CCP1CON = 0x05;
while (!(PIR1bits.CCP1IF));
CCP1CON = 0x00; //disable CCP1 capture */
period = CCPR1 -per1 ;
thigh=thigh-per1;
total=period*0.2;  // o,2   convert to  us  from  clock  cyckle
 th=thigh*0.2;
z=th*100;
t=total;
dutycycle=z/t;
dekadikos=dutycycle ;



ultoa(total,str);// convert integer in to string
	
putsXLCD(str);

	
	
ultoa(th,str);// convert integer in to string

    	putsXLCD(str);

DelaySTRING();


ultoa( dutycycle,str);  // convert integer in to string

	putsXLCD(str);
DelaySTRING();



    while(1);// Wait here
}





void DelayFor18TCY(void)
{
Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();

}


/****************************************************************/
//  DelayPORXLCD  =15 ms.
/****************************************************************/

void DelayPORXLCD(void)
{
Delay1KTCYx(75);
}

/****************************************************************/
//  DelayXLCD  =5 ms.
/****************************************************************/

void DelayXLCD(void)
{
Delay1KTCYx(25);
}

/****************************************************************/
//  DelayString  =250 ms.
/****************************************************************/

void DelaySTRING(void)
{
Delay10KTCYx(456);//450//1562
}

i haven't add most of the lcd functions so the code is more readable .

Can anyone help me fix that problem

thank you.
 
You haven't added any code functions! :eek: Please post the actual math code, and the variable initialisation.

Without that info we can only guess, so here's a guess;
doing (Thigh * 100) is probably overflowing the variable size once Thigh gets large enough. You need to switch to a 16bit or 32bit variable to do the *100 math. Once finished you can copy the result back to your normal variable for display as duty %.
 
thank you for answer
i forgot mention that i 'm working with c18 lite
this is the full code
Code: 
#include<p18f452.h>
#include<xlcd.h>// Include function definitions for the External LCD Library library
#include<delays.h>// Include function definitions for built in Delay routines
#include <stdio.h>
#include <timers.h>
#include <capture.h>
#include <stdlib.h> /**********tin aferesa epeidi ekane problima sto itoa. Kanonika auti einai bibliothiki poy exei to idoa mesa tin ebala otan ebla ton ADC kodika Den ipirxe prin. Douleue sosta xvris ayti*/

#include <math.h>

#pragma config LVP=OFF
#pragma config OSC=HS
#pragma config WDT=OFF// Use internal Oscillator, Watchdog off, LVP off
#pragma config DEBUG=ON

 






void DelaySTRING(void);
void main(void)
{




	int i,z,t,x;
 unsigned    int period,per1; // unsigned
unsigned int total;
 unsigned int thigh;
unsigned int th;
float dutycycle;
int dekadikos;
int c2=22;
 float y,c1;

   overlay   char data[]="total time ";
	static const char data1[]="in us";
     overlay  char start[]="thigh in us ";
unsigned char  duty[]="duty cycle in % ";
char str[5];

	unsigned char newlineadd=0x40; // Line 2 addresses are 40h to 4Fh
    
	ADCON1=0X7F;//Make all ports Digital	

	OpenXLCD( EIGHT_BIT & LINES_5X7 );// Use 8 bit Data, 5x7 pixel Matrix per character
	while( BusyXLCD());// Wait till LCD finishes executing command
	WriteCmdXLCD( CURSOR_ON);// Turn cursor ON
    WriteCmdXLCD(0x83); // Force curson to the begining of 1st line
	while( BusyXLCD() );// Wait till LCD finishes executing command
   WriteCmdXLCD( SHIFT_DISP_LEFT );//Shift Cursor Display Left
	while( BusyXLCD());// Wait till LCD finishes executing command
     
	putsXLCD(data);// Write the String data to the LCD
DelaySTRING();
WriteCmdXLCD(0b00000001);
	while( BusyXLCD() );
   WriteCmdXLCD( 0xC0);// Force curson to the begining of 2nd line
  
	while( BusyXLCD() );

    putsXLCD(data1);// Write the String data to the LCD
   while( BusyXLCD());
  DelaySTRING();
WriteCmdXLCD(0b00000001);
	while( BusyXLCD());// Wait till LCD finishes executing command
TRISCbits.TRISC2 = 1; /* configure CCP1 pin for input */
T3CON = 0x81; /* use Timer1 as the time base for CCP1 capture */
PIE1bits.CCP1IE = 0; /* disable CCP1 capture interrupt */
PIR1bits.CCP1IF = 0; /* clear the CCP1IF flag */
T1CON = 0x81; /* enable 16-bit Timer1, prescaler set to 1 */
CCP1CON = 0x05; /* capture on every rising edge */
while (!(PIR1bits.CCP1IF)); /* wait for 1st rising edge */
PIR1bits.CCP1IF = 0;
per1 = CCPR1; /* save the first edge (CCPR1 is accessed as a 16-bit value) */
PIE1bits.CCP1IE = 0;
CCP1CON = 0x04;
while (!(PIR1bits.CCP1IF)); /* wait for the 2nd rising edge */
PIR1bits.CCP1IF = 0;
thigh=CCPR1;
PIE1bits.CCP1IE = 0;
CCP1CON = 0x05;
while (!(PIR1bits.CCP1IF));
CCP1CON = 0x00; //disable CCP1 capture */
period = CCPR1 -per1 ;
thigh=thigh-per1;
total=period*0.2;
th=thigh*0.2;
z=th*100;
t=total;
dutycycle=z/t;
dekadikos=dutycycle ;


while( BusyXLCD() );


WriteCmdXLCD( 0xC5);//
while( BusyXLCD() );

ultoa(total,str);// convert integer in to string
SetDDRamAddr( newlineadd );
	while( BusyXLCD() );	
putsXLCD(str);
DelaySTRING();
DelaySTRING();
	while( BusyXLCD() );
DelaySTRING();
WriteCmdXLCD(0b00000001);
	while( BusyXLCD() );
 WriteCmdXLCD(0x80); // Force curson to the begining of 1st line
	while( BusyXLCD() );// Wait till LCD finishes executing command
     putsXLCD(start);	
	while( BusyXLCD() );
 WriteCmdXLCD(0xC4); // Force curson to the begining of 1st line
	while( BusyXLCD() );// Wait till LCD finishes executing command
ultoa(th,str);// convert integer in to string
SetDDRamAddr( newlineadd );
	while( BusyXLCD() );
    	putsXLCD(str);
DelaySTRING();
	while( BusyXLCD() );
DelaySTRING();
WriteCmdXLCD(0b00000001);
while( BusyXLCD() );
 WriteCmdXLCD(0x80);
putsXLCD(duty);
DelaySTRING();
	while( BusyXLCD() );
 WriteCmdXLCD(0xC2); // Force curson to the begining of 1st line
	while( BusyXLCD() );// Wait till LCD finishes executing command
ultoa(dekadikos,str);// convert integer in to string
//SetDDRamAddr( newlineadd );
	while( BusyXLCD() );
	putsXLCD(str);
DelaySTRING();
while( BusyXLCD() );
x=dekadikos;
c1=c2*x;
c1=c1/10;


WriteCmdXLCD(0xC8); // Force curson to the begining of 1st line
	while( BusyXLCD() );// Wait till LCD finishes executing command
ultoa(c1,str);// convert integer in to string
//SetDDRamAddr( newlineadd );
	while( BusyXLCD() );
	putsXLCD(str);

    while(1);// Wait here
}





void DelayFor18TCY(void)
{
Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();
	Nop();

}


/****************************************************************/
//  DelayPORXLCD  =15 ms.
/****************************************************************/

void DelayPORXLCD(void)
{
Delay1KTCYx(75);
}

/****************************************************************/
//  DelayXLCD  =5 ms.
/****************************************************************/

void DelayXLCD(void)
{
Delay1KTCYx(25);
}

/****************************************************************/
//  DelayString  =250 ms.
/****************************************************************/

void DelaySTRING(void)
{
Delay10KTCYx(456);//450//1562
}

How to i switch it to 16 bit?
 
Sorry I must aplologise! I re-installed by web browser and now it seems broken, it is only showing the top 16 lines of the CODE PANEL, so I can't see any of your code below that! To me it looked like you only posted the top few lines. :(

The best I can give you is a general technique.

If you multiply something by 100, you must do it within a variable that is large enough to hold the result.

You said you are using;
dutycycle = (Thigh *100)/period;

To be safe, you can force all the math to be done inside a 32bit variable;
unsigned long math32; // this is the variable you will use

math32 = Thigh; // after this point all the math is done inside the 32bit variable!
dutycycle = (math32 *100)/period; // your same calc, but now is safe to 32bits (largest number about 4 billion)
 
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