Project 2 - Measuring distance of an object using ultrasonic sensor (HC-SR04)
Abhinaya Inbamani mam Live batch
# define F_CPU 8000000UL//system clock frequency as 8 MHz.
#include <avr/io.h>// contains input/output definitions for the AVR micro controller.
#include <avr/interrupt.h>//interrupt header file, which contains definitions for handling interrupts.
#include <util\delay.h>//includes the delay header file, which contains delay functions
#include <string.h>//string header file, which contains functions for manipulating strings.
#include <stdlib.h>//standard library header file, which contains functions for general purposes.
#define lcdport PORTD// port used for the data transfer to the LCD.
#define rs (1<<4) // register select pin for the LCD.
#define rw (1<<3)// read/write pin for the LCD.
#define en (1<<2) //enable pin for the LCD.
#define LCD_data_port PORTD//port used for data transfer to the LCD.
#define LCD_Cmd_Port PORTC//port used for command transfer to the LCD.
void lcd_command(unsigned char cmd)//function that sends a command to the LCD display
{
lcdport = cmd; // sends the command to the LCD data port.
LCD_Cmd_Port &= rs | rw;//clears the register select and read/write pins of the LCD command port.
LCD_Cmd_Port |= en;//enable pin of the LCD command port.
_delay_ms(1);
LCD_Cmd_Port &= en;// clears the enable pin of the LCD command port.
}
void lcd_data(unsigned char data)//function that sends data to the LCD display
{
lcdport = data;// sends the data to the LCD data port.
LCD_Cmd_Port &= rw;//clears the read/write pin of the LCD command port.
LCD_Cmd_Port |= rs;//sets the register select pin of the LCD command port.
LCD_Cmd_Port |= en;// sets the enable pin of the LCD command port.
_delay_ms(1);
LCD_Cmd_Port &= en;//clears the enable pin of the LCD command port.
}
void lcd_init()// function initializes the LCD display
{
lcd_command(0x38);_delay_ms(5);//Function set - sets the data length (8 bits), number of lines (2), and font type.
lcd_command(0x02);_delay_ms(5);//Return home - sets the cursor to the home position (upper left corner).
lcd_command(0x01);_delay_ms(5);// Clear display - clears the display and sets the cursor to the home position.
lcd_command(0x0c);_delay_ms(5);//Display on/off control - turns the display on, cursor off, and blinking cursor off.
lcd_command(0x06);_delay_ms(5);//Entry mode set - sets the cursor to move right after each character is displayed.
lcd_command(0x80);_delay_ms(5);//Set DDRAM address - sets the DDRAM (display data RAM) address to 0, which corresponds to the home position on the display.
}
void cursorpos(char x, char y)
{
if( (x < 1 || x > 2) || (y < 1 || y > 16) ) // rows and columns
{
x = 1;
y = 1;
}
if(x == 1)
lcd_command(0x7F+y);
else
lcd_command(0xBF+y);
}
void lcd_out(char x, char y, char *str)
{
cursorpos(x, y);
while (*str)
{
lcd_data(*str);
str++;
}
}
#define Trig_pin PORTA //sets its value to PORTA.
int TimerOverFlow = 0;// declares an integer variable named TimerOverFlow and initializes its value to 0.
ISR(TIMER1_OVF_vect)//ISR is called when the Timer/Counter1 module overflows
{
TimerOverFlow++;//When the ISR is called, the TimerOverFlow variable is incremented by 1.
}
int main(void)
{
char string[10];
long count;
double distance;
DDRA = 0X01; // set PA0 as output pin
PORTB = 0XFF; //Turn on pull-up for PORTB
lcd_init();//calling initialize the LCD display
lcd_out(1,0,"Ultrasonic");//display "Ultrasonic" on the first line of the LCD
sei(); //enable global interrupts
TIMSK = (1<<TOIE1);////enable timer overflow interrupt for Timer1
TCCR1A =0X00; //set Timer1 to normal mode
while (1)
{
PORTA |= (1<<Trig_pin);//send a 10us high pulse to the ultrasonic sensor
_delay_us(10);
PORTA &=~ (1<<Trig_pin);
TCNT1 = 0X00; //set Timer1 counter value to 0
TCCR1B = 0X41; //start Timer1 with prescaler 1:1
TIFR =1<< ICF1; //clear Input Capture Flag of Timer1
TIFR = 1<<TOV1; //clear Timer Overflow Flag of Timer1
while ((TIFR & (1<<ICF1))==0); //wait for the Input Capture Flag to be set
count = ICR1 + (65535 * TimerOverFlow);//calculate the count value
distance = (double)count/466.47;//calculate the distance in cm
dtostrf(distance, 2, 2, string);//convert the distance to a string
strcat(string, "cm");//add the unit "cm" to the string
lcd_out(2,0,"Dist =");//display "Dist =" on the second line of the LCD
lcd_out(2,7,string);//display the distance value on the second line of the LCD
_delay_ms(200); //delay for 200ms before sending another pulse
}
}