The Code
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#include <avr /io.h>
#include <avr /interrupt.h>
#include <util /delay.h>
#include <stdlib.h>
#define enable PORTD3
#define registerselection PORTD5
void send_a_command(unsigned char command);
void send_a_character(unsigned char character);
void send_a_string(char *string_of_characters);
uint16_t us_measurement();
void set_compare(uint16_t);
void set_period(uint16_t);
void timer3_init();
static volatile int pulse = 0;
static volatile int i = 0;
int kalle;
int main(void)
{
DDRB = 0xFF;
DDRD = 0xFF;
DDRC |=(1<<PORTC0); DDRD &=~(1<<PORTD7); _delay_ms(50); timer3_init(); set_period(58); float COUNTA=0; char SHOWA [16]; send_a_command(0x01); send_a_command(0x38); _delay_ms(50); send_a_command(0b00001111); _delay_ms(50); while(1) {
set_compare(us_measurement()); COUNTA=us_measurement()*2.0; send_a_string ("DISTANCE=");
itoa(COUNTA,SHOWA,10);
send_a_string(SHOWA);
send_a_string (" cm ");
send_a_command(0x80 + 0);
_delay_ms(60);
if(COUNTA <= 5){
_delay_ms(60);
PORTD |=(1<<PORTD1);
_delay_ms(1000);
PORTD &=~(1<<PORTD1);
}
}
}
void send_a_command(unsigned char command)
{
PORTB = command;
PORTD &= ~ (1<<registerselection);
PORTD |= 1<<enable;
_delay_ms(8);
PORTD &= ~1<<enable;
PORTB = 0;
}
void send_a_character(unsigned char character)
{
PORTB = character;
PORTD |= 1<<registerselection;
PORTD |= 1<<enable;
_delay_ms(8);
PORTD &= ~1<<enable;
PORTB = 0;
}
void send_a_string(char *string_of_characters)
{
while(*string_of_characters > 0)
{
send_a_character(*string_of_characters++);
}
}
void timer3_init() {
TCCR3A &= ~(1 << COM3A1);
TCCR3A &= ~(1 << COM3A0);
TCCR3A |= (1 << WGM31);
TCCR3B |= (1 << WGM33) | (1 << WGM32) | (1 << CS30) | (1 << CS32);
}
void set_compare(uint16_t ocr){
OCR3A = ocr;
}
void set_period(uint16_t icr){
ICR3 = icr;
}
uint16_t us_measurement(){
_delay_ms(60);
TCNT1 = 0;
PORTC |= (1 << PORTC0);
_delay_us(10);
PORTC &= ~(1 << PORTC0);
while(!(PIND & (1 << PIND7)));
TCCR1B |= (1 << CS12) | (1 << CS10) ;
while((PIND & (1 << PIND7)));
TCCR1B = 0;
kalle = TCNT1;
return TCNT1;
}
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