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

#define F_CPU 8000000UL
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include
#include

#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 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;
LCD_Command_Port &= ~((1<<RS)|(1<<RW));
LCD_Command_Port |= (1<<EN);
_delay_us(1);
LCD_Command_Port &= ~(1<<EN);
_delay_ms(3);
}

void LCD_Char (char char_data)
{
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);
_delay_us(1);
LCD_Command_Port &= ~(1<<EN);
_delay_ms(1);
}

void LCD_Init (void)
{
LCD_Command_Dir |= (1<<RS)|(1<<RW)|(1<<EN);

LCD_Data_Dir = 0xFF;

_delay_ms(20); // LCD power up time to get things ready, it should always >15ms //
LCD_Command (0x38);
LCD_Command (0x0C);
LCD_Command (0x06);
LCD_Command (0x01);
LCD_Command (0x80);
}

void LCD_String (char str)
{
int i;
for(i=0;str[i]!=0;i++) //
{
LCD_Char (str[i]);
}
}

void LCD_String_xy (char row, char pos, char str)
if (row == 1)
LCD_Command((pos & 0x0F)|0x80);
else if (row == 2)
LCD_Command((pos & 0x0F)|0xC0);
LCD_String(str);
}
#define Trigger_pin PA0

int TimerOverflow = 0;

ISR(TIMER1_OVF_vect)
{
TimerOverflow++;
}

int main(void)
{
char string[10];
long count;
double distance;

DDRA = 0x01;
PORTB = 0xFF; //Turn on Pull-up //

LCD_Init();
LCD_String_xy(1, 0, "Ultrasonic");

sei(); // Enable global interrupt //
TIMSK = (1 << TOIE1);
TCCR1A = 0;

while(1)
{
PORTA |= (1 << Trigger_pin);
_delay_us(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//

while ((TIFR & (1 << ICF1)) == 0); //
TCNT1 = 0;
TCCR1B = 0x01;
TIFR = 1<<ICF1;
TIFR = 1<<TOV1;

TimerOverflow = 0;

while ((TIFR & (1 << ICF1)) == 0);
count = ICR1 + (65535 * TimerOverflow); distance = (double)count / 466.47;

dtostrf(distance, 2, 2, string); //distance to string //
strcat(string, " cm ");
LCD_String_xy(2, 0, "Dist = ");
LCD_String_xy(2, 7, string); //Print distance //
_delay_ms(200);
}
}