Project 2 - Measuring the distance of an object using ultrasonic sensor and also smoothen the sensor data using moving average filter

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

code:

#include <avr/io.h>
#define F_CPU 16000000L
#include <util/delay.h>
#define rs_high PORTD |=(1<<0);//DEFINE BIT FOR RS_HIGH
#define rs_low PORTD &=~(1<<0);//DEFINE BIT FOR RS_LOW
#define en_high PORTD |= (1<<2);//DEFINE BIT FOR EN_HIGH
#define en_low PORTD &=~(1<<2);//DEFINE BIT FOR EN_LOW
#define rw_high PORTD |= (1<<1);
#define rw_low PORTD &= ~(1<<1);
#define US_ERROR		-1      // we're defining two more variables two know if the ultrasonic sensor is working or not
#define	US_NO_OBSTACLE	-2
#define US_PORT PORTC           // we have connected the Ultrasonic sensor on port C. to use the ultrasonic we need two pins of the ultrasonic to be connected on port C
#define	US_PIN	PINC            // we need to initialize the pin resistor when we want to take input.
#define US_DDR 	DDRC            // we need data-direction-resistor (DDR) to set the direction of data flow. input or output. we will define it later, now we're just naming it.
#define US_TRIG_POS	PC0         // the trigger pin of ultrasonic sound sensor is connected to port C pin 0
#define US_ECHO_POS	PC1
int distance, previous_distance;

void lcd_cmd(unsigned char cmd)//LCD_COMMAND FUNCTION
{
	PORTB = cmd;
	rs_low;
	rw_high;
	en_high;
	_delay_ms(1);
	en_low;
}
void lcd_data(unsigned char data)//LCD DATA FUNCTION
{
	PORTB = data;
	rw_low;
	rs_high;
	en_high;
	_delay_ms(1);
	en_low;
}
void lcd_init()//LCD INITILIAZATION
{
	rw_high;
	rs_high;
	en_high;
	PORTB = 0xff;
	lcd_cmd(0x38);
	_delay_ms(5);
	lcd_cmd(0x02);
	_delay_ms(5);
	lcd_cmd(0x01);
	_delay_ms(5);
	lcd_cmd(0x0c);
	_delay_ms(5);
	lcd_cmd(0x06);
	_delay_ms(5);
	lcd_cmd(0x80);
	_delay_ms(5);
}
void cursorpos(char x,char y)//CURSOR POSITION FUNCTION
{
	if((x<1 || x>2)||(y<1 || y>16))
	{
		x=1;
		y=1;
	}
	if (x==1)
	{
		lcd_cmd(0x7F+y);
	}
	else
	{
		lcd_cmd(0xBF+y);
	}
}
void lcd_out(char a, char b,char *str)//LCD OUT FUNCTION
{
	cursorpos(a,b);
	while(*str)
	{
		lcd_data(*str);
		str++;
	}
}
void lcd_clear()
{
	lcd_cmd (0x01);   // this line clears the LCD screen
	_delay_ms(2);         // waits for two milliseconds
	lcd_cmd (0x80);   // this line sets the cursor to the row 1 column 1
}
void HCSR04Init()
{
	// we're setting the trigger pin as output as it will generate ultrasonic sound wave
	US_DDR|=(1<<US_TRIG_POS);
}
void HCSR04Trigger()
{   // this function will generate ultrasonic sound wave for 15 microseconds
	//Send a 10uS pulse on trigger line
	US_PORT|=(1<<US_TRIG_POS);	//high
	_delay_us(15);				//wait 15uS
	US_PORT&=~(1<<US_TRIG_POS);	//low
}
uint16_t GetPulseWidth()
{
	// this function will be used to measure the pulse duration. When the ultra sound echo back after hitting an object
	// the microcontroller will read the pulse using the echo pin of the ultrasonic sensor connected to it.
	uint32_t i,result;
	// Section - 1: the following lines of code before the section - 2 is checking if the ultrasonic is working or not
	// it check the echo pin for a certain amount of time. If there is no signal it means the sensor is not working or not connect properly
	for(i=0;i<600000;i++)
	{
		if(!(US_PIN & (1<<US_ECHO_POS)))
		continue;	//Line is still low, so wait
		else
		break;		//High edge detected, so break.
	}
	if(i==600000)
	return US_ERROR;	//Indicates time out
	//High Edge Found
	// Section -2 : This section is all about preparing the timer for counting the time of the pulse. Timers in microcontrllers is used for timimg operation
	//Setup Timer1
	TCCR1A=0X00;
	TCCR1B=(1<<CS11);	// This line sets the resolution of the timer. Maximum of how much value it should count.
	TCNT1=0x00;			// This line start the counter to start counting time
	// Section -3 : This section checks weather the there is any object or not
	for(i=0;i<600000;i++)                // the 600000 value is used randomly to denote a very small amount of time, almost 40 miliseconds
	{
		if(US_PIN & (1<<US_ECHO_POS))
		{
			if(TCNT1 > 60000) break; else continue;   // if the TCNT1 value gets higher than 60000 it means there is not object in the range of the sensor
		}
		else
		break;
	}
	if(i==600000)
	return US_NO_OBSTACLE;	//Indicates time out
	//Falling edge found
	result=TCNT1;          // microcontroller stores the the value of the counted pulse time in the TCNT1 register. So, we're returning this value to the
	// main function for utilizing it later
	//Stop Timer
	TCCR1B=0x00;
	if(result > 60000)
	return US_NO_OBSTACLE;	//No obstacle
	else
	return (result>>1);
}
int main()
{
	lcd_init();           // we're initializing the LCD
	char numberString[4];   // we re defining an array of character. It will be utilized later to store integer to be displayed on the LCD screen
	while(1) {
		uint16_t r;
		_delay_ms(100);	//Let the LCD Module start
		//Set io port direction of sensor
		HCSR04Init();                                              
		while(1)
		{
			//Send a trigger pulse
			HCSR04Trigger();               // calling the ultrasonic sound wave generator function
			//Measure the width of pulse
			r=GetPulseWidth();             // getting the duration of the ultrasound took to echo back after hitting the object
			//Handle Errors
			if(r==US_ERROR)                // if microcontroller doesn't get any pulse then it will set the US_ERROR variable to -1
			// the following code will check if there is error then it will be displayed on the LCD screen
			{
				cursorpos(1, 1);      //lcd_setCursor(column, row)
				char j[10] = "Error!";
				lcd_out(1,1,&j);
			}
			else
			{
				distance=(r*0.034/2.0);	// This will give the distance in centimeters				
				char f[15]= "Distance = ";
				lcd_out(1,0,&f);
				itoa(distance, numberString, 10);    // distance is an integer number, we can not display integer directly on the LCD. this line converts integer into array of character
				lcd_out(2,4,numberString);
				char h[6] = " cm";
				lcd_out(2,10,&h);
				previous_distance = distance;
				_delay_ms(30);
			}
		}
		
	}
}

• The distance travelled by a wave to the object for which we want to measure the distance using Ultrasonic Distance Sensor (HC-SR04).
• Measuring Pulse width using Input Capture Mode of Timer 1

Circuit Daigram:

The students will get the Knowledge on Ultrasonic sensor (HC-SR04) to measure the distance travelled by wave to the object, the hardware connection of Atmega328p and HC-SR04 and how to use input capture mode of Timer1

circuit :

all required file is below atteched.