Project 2 - Measuring distance of an object using ultrasonic sensor (HC-SR04)
CIRCUIT :
CODE :
/*
* project2.c
*
* Created: 24-04-2023 22:06:29
* Author : Divya
*/
#define F_CPU 8000000UL // define the crystal frequency
#include //we are using I/O registers of AVR
#include // we are using external interrupt pin
#include // delay function purpose
#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 LCD data port
#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; // Write command data to LCD data port
LCD_Command_Port &= ~((1<<rs)|(1<<rw)); ="" <span=""> // Make RS LOW (command reg.), RW LOW (Write) </rs)|(1<<rw)); >
LCD_Command_Port |= (1<<en); ="" <span=""> // High to Low transition on EN (Enable) </en); >
_delay_us(1);
LCD_Command_Port &= ~(1<<en);< p=""></en);<>
_delay_ms(3); // Wait little bit
}
void LCD_Char (char char_data) // LCD data write function
{
LCD_Data_Port = char_data; // Write data to LCD data port
LCD_Command_Port &= ~(1<<rw); <span=""> // Make RW LOW (Write) </rw); >
LCD_Command_Port |= (1<<en)|(1<<rs); <span=""> // Make RS HIGH (data reg.) and High to Low transition on EN (Enable) </en)|(1<<rs); >
_delay_us(1);
LCD_Command_Port &= ~(1<<en);< p=""></en);<>
_delay_ms(1); // Wait little bit
}
void LCD_Init (void) // LCD Initialize function
{
LCD_Command_Dir |= (1<<rs)|(1<<rw)|(1<<en); ="" <span=""> // Make LCD command port direction as o/p </rs)|(1<<rw)|(1<<en); >
LCD_Data_Dir = 0xFF; // Make LCD data port direction as o/p
_delay_ms(20); // LCD power up time to get things ready, it should always >15ms
LCD_Command (0x38); // Initialize 16X2 LCD in 8bit mode
LCD_Command (0x0C); // Display ON, Cursor OFF command
LCD_Command (0x06); // Auto Increment cursor
LCD_Command (0x01); // Clear LCD command
LCD_Command (0x80); // 8 is for first line and 0 is for 0th position
}
void LCD_String (char *str) // Send string to LCD function
{
int i;
for(i=0;str[i]!=0;i++) // Send each char of string till the NULL
{
LCD_Char (str[i]); // Call LCD data write
}
}
void LCD_String_xy (char row, char pos, char *str) // Send string to LCD function
{
if (row == 1)
LCD_Command((pos & 0x0F)|0x80); // Command of first row and required position<16
else if (row == 2)
LCD_Command((pos & 0x0F)|0xC0); // Command of Second row and required position<16
LCD_String(str); // Call LCD string function
}
#define Trigger_pin PA0 // Trigger pin
int TimerOverflow = 0;
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_String_xy(1, 0, "Ultrasonic");
sei(); // Enable global interrupt
TIMSK = (1 << TOIE1); // Enable Timer1 overflow interrupts
TCCR1A = 0; // Set all bit to zero Normal operation
while(1)
{
/* Give 10us trigger pulse on trig. pin to HC-SR04 */
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; ="" <span=""> // Clear ICP flag (Input Capture flag) </icf1; >
TIFR = 1<<tov1; ="" <span="">// Clear Timer Overflow flag </tov1; >
/*Calculate width of Echo by Input Capture (ICP) */
while ((TIFR & (1 << ICF1)) == 0); // Wait for rising edge
TCNT1 = 0; // Clear Timer counter
TCCR1B = 0x01; // Capture on falling edge, No prescaler
TIFR = 1<<icf1; ="" <span="">// Clear ICP flag (Input Capture flag) </icf1; >
TIFR = 1<<tov1; ="" <span=""> // Clear Timer Overflow flag </tov1; >
TimerOverflow = 0; // Clear Timer overflow count
while ((TIFR & (1 << ICF1)) == 0); // Wait for falling edge
count = ICR1 + (65535 * TimerOverflow); // Take count
/* 8MHz Timer freq, sound speed =343 m/s */
distance = (double)count / 466.47;
dtostrf(distance, 2, 2, string); // distance to string
strcat(string, " cm "); // Concat unit i.e.cm
LCD_String_xy(2, 0, "Dist = ");
LCD_String_xy(2, 7, string); // Print distance
_delay_ms(200);
}
}
OUTPUT :
