Meranie vzdialenosti ultrazvukovým snímačom HC-SR04: Rozdiel medzi revíziami

#include <avr/io.h>
#include <util/delay.h>
#include <stdio.h>
#include "uart.h"
volatile uint16_t distance = 0; //tu budeme ukladat vzdialenost, ako cele cislo o velkosti 16 bitov
FILE mystdout = FDEV_SETUP_STREAM(uart_putc, NULL, _FDEV_SETUP_WRITE);

void UART_Transmit(unsigned char data) {
    while (!(UCSR0A & (1<<UDRE0))); // Caka na prazdny buffer
    UDR0 = data;
}

void trigger_pulse() {
    PORTB |= (1 << PB1);  // Nastavi Trig pin na vysoku uroven
    _delay_us(10);              // Caka 10 mikrosekund
    PORTB &= ~(1 << PB1); // Nastavi Trig pin na nizku uroven
}

uint16_t measure_pulse_width() {
    uint16_t pulse_width = 0;
    uint16_t timeout = 50000; // Aby sme nesli donekonecna

    // Caka na Echo pin, kym bude na vysokej urovni
    while (!(PINB & (1 << PB2)) && timeout--) {
        _delay_us(1);
    }

    // Mera dlzku signalu
    while ((PINB & (1 << PB2)) && timeout--) {
        _delay_us(1);
        pulse_width++;
    }

    // Vypocitame vzdialenost v cm
    uint16_t distance = pulse_width / 58;
    return distance;
}

int main(void) {
    DDRB |= (1 << PB1); // Nastavi Trig pin ako vystup
    DDRB &= ~(1 << PB2); // Nastavi Echo pin ako vstup
	PORTB |= (1 << PB2); // Ovladanie pull-up rezistoru
	
	hw_init();
    uart_init();
    stdout= &mystdout;
	
    while (1) {
         trigger_pulse(); // Posle signal na senzor
		 uint16_t distance = measure_pulse_width(); // Merame vzdialenost a vypocitame ju v cm
        printf("Vzdialenost: %d cm\n", distance); // Vypiseme vzdialenost cez napr. Putty
        _delay_ms(500); // Pockame pred dalsim meranim
    }
    return 0;
}

/* ************************************************************************* */
/* FileName:             uart.h                                              */
/* ************************************************************************* */

#define LED PB5  // internal on-board LED 

 /* na testovanie su uz zadefinovane */
 // bit_is_set(PINB, SW1)
 // bit_is_clear(PINB, SW1)

 /* na cakanie su preddefinovane slucky */
 // loop_until_bit_is_set(PINB, SW1);    // cakanie na uvolnenie tlacitka
 // loop_until_bit_is_clear(PINB, SW1);  // cakanie na stlacenie tlacitka


#define set_bit(ADDRESS,BIT) (ADDRESS |= (1<<BIT))
#define clear_bit(ADDRESS,BIT) (ADDRESS &= ~(1<<BIT))

#ifndef UART_H_
#define UART_H_

#include <stdio.h>

#define BAUD_PRESCALE  (((F_CPU / (BAUDRATE * 16UL))) - 1)  // vzor?ek z datasheetu

void hw_init( void );
void uart_init( void );
     
/* Following definition is compatible with STDIO.H, for more
 * information see https://www.appelsiini.net/2011/simple-usart-with-avr-libc/
 */
	 
int uart_putc( char c, FILE *stream );
void uart_puts( const char *s );

char uart_getc( void );

void delay(int delay); 

#endif /* UART_H_ */

/* ************************************************************************* */
/* FileName:             uart.c                                              */
/* ************************************************************************* */

#include <avr/io.h>
#include <util/delay.h>
#include "uart.h"

void hw_init( void )
{ 
  DDRB |= (1<<LED);    // PORTB.5 kde je LED ma byt OUTPUT
  /* sem si mozete dopisat svoje vlastne inicializacne prikazy */ 	
}

void uart_init( void ) 
{
//  for different BAUD rate change the project settings, or uncomment 
//  following two lines:	
//	#undef  BAUD           // avoid compiler warning
//  #define BAUD 115200
	
   #include <util/setbaud.h>  // requires defined BAUD
   
   UBRR0H = UBRRH_VALUE;
   UBRR0L = UBRRL_VALUE;
   #if USE_2X                 // defined in setbaud.h 
    UCSR0A |= (1 << U2X0);
   #else
    UCSR0A &= ~(1 << U2X0);
   #endif


    UCSR0C = _BV(UCSZ01) | _BV(UCSZ00); /* 8-bit data */
    UCSR0B = _BV(RXEN0) | _BV(TXEN0);   /* Enable RX and TX */	
}


int uart_putc( char c, FILE *stream )
{
   if (c == '\n') 
      uart_putc('\r',stream);
   
   loop_until_bit_is_set(UCSR0A, UDRE0); /* Wait until data register empty. */
   UDR0 = c;
   return 0;
}


void uart_puts(const char *s)
{
  /* toto je vasa uloha */
}

char uart_getc(void) 
{
    loop_until_bit_is_set(UCSR0A, RXC0); /* Wait until data exists. */
    return UDR0;
}

void delay(int delay)      // vlastna funkcia pre dlhsie casy 
{
  for (int i=1; i<=delay; i++)
  _delay_ms(1);
}