[AVR] 8 bit timer register shows values greater than 255

[ANS HAFEEZ]

SALAM TO AALL;
i am using 8-bit timer in normal mode and when i continously read TCNT register of atmega32 and show values on LCD then it show values above 255 some time value reached to 900 im not getting where the problem...

 

[milan.rajik]

Maybe the LCD display routine causing the problem. Show LCD related code.

 

[ANS HAFEEZ]

MAIN HEADER FILE
#define DATA_BUS DDRD      //  LCD databus Direction Configuration
#define CONTROL_BITS DDRC  //  LCD Control bus Direction Configuration

#define DB	PORTD             //	LCD databus connected to PORTB
#define CB PORTC        //	LCD Control bus connected to PORTD

#define rs 0                    // Register select pin connected 6th bit(D5) Control bus
#define rw 1                   // Read Write pin connected to 7th bit(D6) Control bus
#define en 2                  // Enable pin connected to 8th bit(D7) Control bus

#define LCDMaxLines 2
#define LCDMaxChars 16
#define LineOne 0x80
#define LineTwo 0xc0
void LCD_CmdWrite( char cmd)
{
	
	DB=cmd;             // Send the command to LCD
	CB &=~(1<<rs);  // Select the Command Register by pulling RS LOW
	CB &=~(1<<rw);  // Select the Write Operation  by pulling RW LOW
	CB |=1<<en;     // Send a High-to-Low Pusle at Enable Pin
	_delay_us(1);
	CB &=~(1<<en);
	_delay_ms(1);
}
void LCD_DataWrite( char dat)
{
	
	DB=dat;            // Send the data to LCD
	CB |=1<<rs;	// Select the Data Register by pulling RS HIGH
	CB &=~(1<<rw);	// Select the Write Operation  by pulling RW LOW
	CB |=1<<en;	// Send a High-to-Low Pusle at Enable Pin
	_delay_us(1);
	CB &=~(1<<en);
	_delay_ms(1);
	
}
void LCD_Init()
{
	_delay_ms(50);
	DATA_BUS = 0xff;   // Configure both databus and controlbus as output
	CONTROL_BITS = 0xff;
	LCD_CmdWrite(0x38);   // LCD 2lines, 5*7 matrix
	LCD_CmdWrite(0x0C);	// Display ON cursor ON
	LCD_CmdWrite(0x01);	// Clear the LCD
	LCD_CmdWrite(0x80);	// Move the Cursor to First line First Position
}
void LCD_DisplayNumber(unsigned int num)
{
	if (num>10000)
	{
		LCD_DataWrite((num/10000)+0x30);
		num=num%10000;
		
		LCD_DataWrite((num/1000)+0x30);
		num=num%1000;
		
		LCD_DataWrite((num/100)+0x30);
		num=num%100;
		
		LCD_DataWrite((num/10)+0x30);
		
		LCD_DataWrite((num%10)+0x30);
	}
	else if (num>1000)
	{
		LCD_DataWrite((num/1000)+0x30);
		num=num%1000;
		
		LCD_DataWrite((num/100)+0x30);
		num=num%100;
		
		LCD_DataWrite((num/10)+0x30);
		
		LCD_DataWrite((num%10)+0x30);
	}
	else if (num>100)
	{
		LCD_DataWrite((num/100)+0x30);
		num=num%100;
		
		LCD_DataWrite((num/10)+0x30);
		
		LCD_DataWrite((num%10)+0x30);
	}
	else if (num>10)
	{
		LCD_DataWrite((num/10)+0x30);
		LCD_DataWrite((num%10)+0x30);
	}
	else
	LCD_DataWrite((num%10)+0x30);
}
MAIN C FILE
//#define F_CPU 1000000UL
#include <avr/io.h>
#include <util/delay.h>
#include "LCD.h"
void TIMER_ON()
{
	TCCR0 |= ( 1<<CS02) | (1<<CS00); //(1<<CS01);//
}
void PING()
{
	PORTA |= (1 << PINA0);
	_delay_us(10);
	PORTA &= ~(1 << PINA0);
}
int main(void)
{
	LCD_Init();
	TIMER_ON();
	char TYM=0;
	DDRA |= 1 << PINA0;//set pin B0 to be output and connect with trigger pin in the sensor
	DDRA &= ~(1 << PINA1);//set pin B5 to be input
	MCUCSR|= 1<<JTD;
	MCUCSR|= 1<<JTD;
	while(1)
	{
		PING();
		if (bit_is_set(PINA, PINA1)) TYM=TCNT0;
		else TCNT0=0;
		LCD_CmdWrite(0x80);
		LCD_DisplayNumber(TYM);
	}
	return 0;
}

 

[milan.rajik]

How is LCD character position selected ?

 

[ANS HAFEEZ]

How is LCD character position selected ?

LCD_CmdWrite(0x80); // Move the Cursor to First line First Position

 

[milan.rajik]

Try this code.

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Code C - [expand]
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void LCD_DisplayNumber(unsigned int num)
{
    if (num>10000)
    {
        LCD_DataWrite((num/10000)+0x30);
        num=num%10000;
        
        LCD_DataWrite((num/1000)%10+0x30);
        num=num%1000;
        
        LCD_DataWrite((num/100)%10+0x30);
        num=num%100;
        
        LCD_DataWrite((num/10)%10+0x30);
        
        LCD_DataWrite((num%10)+0x30);
    }
    else if (num>1000)
    {
        LCD_DataWrite((num/1000)+0x30);
        num=num%1000;
        
        LCD_DataWrite((num/100)%10+0x30);
        num=num%100;
        
        LCD_DataWrite((num/10)%10+0x30);
        
        LCD_DataWrite((num%10)+0x30);
    }
    else if (num>100)
    {
        LCD_DataWrite((num/100)+0x30);
        num=num%100;
        
        LCD_DataWrite((num/10)%10+0x30);
        
        LCD_DataWrite((num%10)+0x30);
    }
    else if (num>10)
    {
        LCD_DataWrite((num/10)+0x30);
        LCD_DataWrite((num%10)+0x30);
    }
    else
    LCD_DataWrite((num%10)+0x30);
}

---

 

[ANS HAFEEZ]

SAME Problem facing again :bang:

 

[Venkadesh_M]

---

Code C - [expand]
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while(1)
    {
        PING();
        if (bit_is_set(PINA, PINA1)) TYM=TCNT0;
        else TCNT0=0;
        /* Clear display */
        LCD_CmdWrite(0x80);
        LCD_DisplayNumber((unsigned char)TYM);
    }

---

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Code C - [expand]
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void LCD_DisplayNumber(unsigned int num)
{
char digit = 0;
 
if(x = (num/10000)) {
LCD_DataWrite( x +0x30);
num=num%10000;
digit = 1;
}
 
if(x = (num/1000) || digit) {
LCD_DataWrite( x +0x30);
num=num%1000;
digit = 1;
}
 
if(x = (num/100) || digit) {
LCD_DataWrite( x +0x30);
num=num%100;
digit = 1;
}
        
if(x = (num/10) || digit) {
LCD_DataWrite( x +0x30);
num=num%10;
}
        
LCD_DataWrite((num%10)+0x30);
 
}

---