Project 2 - Measuring distance of an object using ultrasonic sensor (HC-SR04)
#define F_CPU 16000000UL
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <string.h>
#include <stdlib.h>
#define LCD_Data DDRD // Define LCD data port direction
#define LCD_Comm 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 signal pin
#define Trigger_pin PA0 // Trigger pin
int TimerOverflow = 0;
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_print (char*); // Send string to LCD function
void LCD_cursor (char,char,char*);// Send row, position and string to LCD function
void LCD_Command (char cmd) // LCD command write function
{
LCD_Data = cmd;
LCD_Comm &= ~((1<<RS)|(1<<RW));
LCD_Comm |= (1<<EN);
_delay_us(1);
LCD_Comm &= ~(1<<EN);
_delay_ms(3);
}
void LCD_Char (char char_data) // LCD data write function
{
LCD_Data = char_data;
LCD_Comm &= ~(1<<RW);
LCD_Comm |= (1<<EN)|(1<<RS);
_delay_us(1);
LCD_Comm &= ~(1<<EN);
_delay_ms(1);
}
void LCD_Init (void) /* LCD Initialize function */
{
LCD_Comm |= (1<<RS)|(1<<RW)|(1<<EN);
LCD_Data = 0xFF;
_delay_ms(20);
LCD_Command (0x38);
LCD_Command (0x0C);
LCD_Command (0x06);
LCD_Command (0x01);
LCD_Command (0x80);
}
void LCD_print (char *str) // Send string to LCD function
{
int i;
for(i=0;str[i]!=0;i++)
{
LCD_Char (str[i]);
}
}
void LCD_cursor (char row, char pos, char *str) // Send string to LCD function */
{
if (row == 1)
LCD_Command((pos & 0x0F)|0x80);
else if (row == 2)
LCD_Command((pos & 0x0F)|0xC0);
LCD_print(str);
}
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_cursor(1, 0, "Ultrasonic");
LCD_cursor(2, 0, "Dist = ");
sei(); // Enable global interrupt
TIMSK = (1 << TOIE1); // Enable Timer1 overflow interrupts
TCCR1A = 0;
while(1)
{
PORTA |= (1 << Trigger_pin);
_delay_us(10);
PORTA &= (~(1 << Trigger_pin));
TCNT1 = 0;
TCCR1B = 0x41; //Capture on rising edge
TIFR = 1<<ICF1; // Clear ICP flag (Input Capture flag)
TIFR = 1<<TOV1; // Clear Timer Overflow flag
while ((TIFR & (1 << ICF1)) == 0);// Wait for rising edge
TCNT1 = 0; // Clear Timer counter
TCCR1B = 0x01; // Capture on falling edge
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;
dtostrf(distance, 2, 2, string);// distance
strcat(string, " cm ");
LCD_cursor(2, 7, string); //Print distance
_delay_ms(200);
}
}