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

Overview of the Project:

In this project, the implementation of code for “Measuring distance of an object using ultrasonic distance sensor (HC-SR04)

Goals:

• Measuring the distance of an object using Ultrasonic Distance Sensor (HC-SR04)
• Usage of Input Capture Mode

Code:-

#include <avr/io.h>

#include <util/delay.h>

#include <avr/interrupt.h>

#include

#include

#define F_CPU 16000000UL

#define lcd_data_dir DDRD

#define lcd_command_dir DDRC

#define lcd_data_port PORTD

#define lcd_command_port PORTC

#define EN PC2

#define RW PC3

#define RS PC4

void lcd_command(char);

void lcd_data(char);

void lcd_init(void);

void lcd_out(char*);

void lcd_print(char, char, char*);

void lcd_command(char cmd)

{

lcd_data_port = cmd;

lcd_command_port &= ~((1 << RS) | (1 << RW));

lcd_command_port |= (1 << EN);

_delay_ms(1);

lcd_command_port &= ~(1 << EN);

_delay_ms(2);

}

void lcd_data(char data)

{

lcd_data_port = data;

lcd_command_port &= ~(1 << RW);

lcd_command_port |= ((1 << EN) | (1 << RS));

_delay_ms(1);

lcd_command_port &= ~(1 << EN);

_delay_ms(1);

}

void lcd_init(void)

{

_delay_ms(20);

lcd_command(0x38);

lcd_command(0x0C);

lcd_command(0x06);

lcd_command(0x01);

lcd_command(0x80);

}

void lcd_out(char *str)

{

while (*str)

{

lcd_data(*str++);

}

}

void lcd_print(char row, char pos, char *str)

{

if (row == 1)

lcd_command((pos & 0x0F) | 0x80); // Move cursor to specified position of the first row

else if (row == 2)

lcd_command((pos & 0x0F) | 0xC0); // Move cursor to specified position of the second row

lcd_out(str); // Display the string at the specified position

}

#define trigger_pin PA0

int TimerOverFlow = 0;

ISR(TIMER1_OVF_vect)

{

TimerOverFlow++;

}

int main(void)

{

char string[10];

long count;

double distance;

lcd_command_dir |= (1 << RS) | (1 << RW) | (1 << EN); // Set control pins as output

lcd_data_dir = 0xFF; // Set data port as output

DDRA = 0x01; // Set PA0 as trigger pin

PORTB = 0xFF; // No need to initialize PORTB

lcd_init(); // Initialize LCD

lcd_print(1, 0, "Ultrasonic"); // Display "Ultrasonic" on the first line

sei(); // Enable global interrupts

TIMSK = (1 << TOIE1); // Enable Timer1 overflow interrupt

TCCR1A = 0; // Configure Timer1 for normal mode

while (1)

{

PORTA |= (1 << trigger_pin); // Generate trigger pulse

_delay_ms(10); // Delay for trigger pulse

PORTA &= ~(1 << trigger_pin); // End trigger pulse

TCNT1 = 0; // Reset Timer1 counter

TCCR1B = 0x41; // Start Timer1 with prescaler 64

TIFR = 1 << ICF1; // Clear Input Capture Flag

TIFR = 1 << TOV1; // Clear Timer1 Overflow Flag

while (!(TIFR & (1 << ICF1))); // Wait for rising edge on Echo pin

TCNT1 = 0; // Reset Timer1 counter

TCCR1B = 0x01; // Start Timer1 with no prescaler

TIFR = 1 << ICF1; // Clear Input Capture Flag

TIFR = 1 << TOV1; // Clear Timer1 Overflow Flag

TimerOverFlow = 0; // Reset Timer1 overflow counter

while (!(TIFR & (1 << ICF1))); // Wait for falling edge on Echo pin

count = ICR1 + (65535 * TimerOverFlow); // Calculate pulse width

distance = (double)count / 466.47; // Calculate distance in centimeters

dtostrf(distance, 2, 2, string); // Convert distance to string

strcat(string, "cm"); // Append "cm" to the distance string

lcd_print(2, 0, "Distance="); // Display "Distance=" on the second line

lcd_print(2, 9, string); // Display the calculated distance on the second line

_delay_ms(200);

}

}

Output:-