Project 2 - Measuring distance of an object using ultrasonic sensor (HC-SR04)

ANS

#include <avr/io.h>
#define F_CPU 16000000ul
#include <util/delay.h>
#include <avr/interrupt.h>
#include<string.h>
#include<stdlib.h>

#define lcd_data_dir DDRD /*Define LCD data port direction*/
#define lcd_command_dir DDRC /*Define LCD command port direction register*/
#define lcd_data_port PORTD /*Define LCD data port*/
#define lcd_command_port PORTC /*Define LCD data port*/
#define EN PC2 /*Define Enable signal pin*/
#define RW PC3 /*Define Read/Write signal pin*/
#define RS PC4 /*Define Register Select(data reg./command reg.)signal pin*/

void lcd_command(char); /*LCD command write function*/
void lcd_char(char); /*LCD data write function*/
void lcd_init(void); /*LCD Initialize function*/
void lcd_string(char*); /*Send string to LCD function*/
void lcd_string_xy (char,char,char*); /*Send row,position and string to LCD function*/

void lcd_command (char cmd) /*LCD command write function*/
{
lcd_data_port = cmd; /*Write command data to LCD data port*/
lcd_command_port&=~((1<<RS)|(1<<RW)); /*Make RS LOW(command reg.),RW LOW(Write)*/
lcd_command_port|= (1<<EN); /*High to Low transition on EN(Enable)*/
_delay_ms(1);
lcd_command_port&=~(1<<EN);
_delay_ms(2); /*Wait little bit*/

}
void lcd_char(char char_data) /*LCD data write function*/
{
lcd_data_port= char_data; /*Write data to LCD data port*/
lcd_command_port&=~(1<<RW); /*Make RW LOW(Write)*/
lcd_command_port|=((1<<EN)|(1<<RS)); /*Make RS HIGH(data reg.)and High to Low transition on EN(Enable)*/
_delay_ms(1);
lcd_command_port&=~(1<<EN);
_delay_ms(1);
}
void lcd_init(void) /*LCD Initialize function*/
{
lcd_command_dir|= (1<<RS)|(1<<RW)|(1<<EN); /*Make LCD command port direction as o/p*/
lcd_data_dir = 0xff; /*Make LCD data port direction as o/p*/
_delay_ms(20); /*LCD power up time to get things ready,it should always>15ms*/
lcd_command(0x38); /*Initialize 16X2 LCD in 8bit mode*/
lcd_command(0x0C); /*Display ON,Cursor OFF command*/
lcd_command(0x06); /*Auto Increment cursor*/
lcd_command(0x01); /*Clear LCD command*/
lcd_command(0x80); /*8 is for first line and0 is for 0th position*/
}
void lcd_string(char *str) /*Send string to LCD function*/
{
int i;
for(i=0;str[i]!=0;i++) /*Send each char of string till the NULL*/
{
lcd_char (str[i]); /*Call LCD data write*/
}

}
void lcd_string_xy(char row,char pos,char *str) /*Send string to LCD function*/
{
if (row == 1)
lcd_command((pos & 0x0f)|0x80); /*Command of first row */
else if (row == 2)
lcd_command((pos & 0x0f)|(0xC0)); /*Command of Second row */
lcd_string(str); /*Call LCD string function*/
}
#define trigger_pin PA0 /*Trigger pin*/
int TimerOverFlow = 0;
ISR(TIMER1_OVF_vect)
{
TimerOverFlow++; /*Increment Timer Overflow count*/
}
int main (void)
{
char string[10];
long count;
double distance;

DDRA = 0x01; /*Make trigger pin as output*/
PORTB = 0xff; /*Turn on Pull-up*/

lcd_init();
lcd_string_xy(1,0,"ultrasonic");

sei(); /*Enable global interrupt*/
TIMSK = (1<< TOIE1); /*Enable Timerl overflow interrupts*/
TCCR1A = 0; /*Set all bit to zero Normal operation*/

while(1)
{
/*Give 10us trigger pulse on trig.pin to HC-SR04*/
PORTA |= (1<< trigger_pin);
_delay_ms(10);
PORTA &=(~(1<< trigger_pin));

TCNT1 = 0; /*Clear Timer counter*/
TCCR1B = 0x41; /*Capture on rising edge,No prescaler*/
TIFR = 1<<ICF1; /*Clear ICP flag(Input Capture flag)*/
TIFR = 1<<TOV1; /*Clear Timer Overflow flag*/
/*Calculate width of Echo by Input Capture(ICP)*/
while ((TIFR & (1<<ICF1)) == 0); /*Wait for rising edge*/
TCNT1 = 0; /*Clear Timer counter*/
TCCR1B = 0x01; /*Capture on falling edge,No prescaler*/
TIFR = 1<<ICF1; /*Clear ICP flag(Input Capture flag)*/
TIFR = 1<<TOV1; /*Clear Timer Overflow flag*/
TimerOverFlow = 0; /*Clear Timer overflow count*/

while ((TIFR & (1<< ICF1))== 0); /*Wait for falling edge*/
count = ICR1 +(65535 * TimerOverFlow); /*Take count*/
distance = (double)count/466.47;
/*8MHz Timer freq,sound speed=343m/s*/
dtostrf(distance,2,2,string); /*distance to string*/
strcat(string,"cm"); /*Concat unit Le.cm*/
lcd_string_xy(2,0,"dist= ");
lcd_string_xy(2,7,string); /*Print distance*/
_delay_ms(200);
}

}

output