Meranie vzdialenosti ultrazvukovým snímačom HC-SR04: Rozdiel medzi revíziami

#include <avr/io.h>
#include "uarth.h"
#define F_CPU 16000000UL
#define BAUDRATE 9600
#include <stdio.h>
FILE mystdout = FDEV_SETUP_STREAM(uart_putc, NULL, _FDEV_SETUP_WRITE);

int main(void)
{
  adc_init();
  hw_init();
  uart_init();
  stdout = &mystdout;          
  unsigned int measuredValue;

  DDRD |= (1 << PD6); // PD6 as output (OC0A)

  TCNT0 = 0; // initialize counter value

  OCR0A = 0; // initialize OCR0A value
                              
  TCCR0A |= (1 << COM0A1) | (1 << COM0B1) | (1 << WGM01) | (1 << WGM00); // set fast PWM mode and non-inverting mode
  TCCR0B |= (1 << CS02) | (1 << CS00); // set prescaler to 1024
  
  while(1)
  {
    measuredValue = adc_read(4); // read ADC from channel 4
    printf("hodnota: %04d \r", measuredValue);
    
    OCR0A = measuredValue / 4; // adjust PWM duty cycle
  }
  
  return 0;
}

#include <avr/io.h>

void adc_init(void);                                  
unsigned int adc_read(char a_pin);

#include <stdio.h>
#include "adc.h"

void adc_init(void) {
  ADMUX = (1 << REFS0); // reference voltage set to AVcc
  ADCSRA = (1 << ADEN) | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // enable ADC and set prescaler to 128
}

unsigned int adc_read(char a_pin) {
  a_pin &= 0x07; // limit input to 0-7
  ADMUX = (ADMUX & 0xF8) | a_pin; // select ADC channel with safety mask
  ADCSRA |= (1 << ADSC); // start conversion
  while (ADCSRA & (1 << ADSC)); // wait for conversion to complete
  return ADC; // return the ADC value
}

#ifndef UARTH_H
#define UARTH_H

#include <avr/io.h>

void uart_init(void);
int uart_putc(char c, FILE *stream);
int uart_getc(FILE *stream);

void uart_init(void) {
  // Set baud rate
  uint16_t baudrate = (F_CPU / (16UL * BAUDRATE)) - 1;
  UBRR0H = (uint8_t)(baudrate >> 8);
  UBRR0L = (uint8_t)baudrate;

  // Enable transmitter and receiver
  UCSR0B = (1 << TXEN0) | (1 << RXEN0);

  // Set frame format: 8 data bits, 1 stop bit
  UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
}

int uart_putc(char c, FILE *stream) {
  if (c == '\n') {
    uart_putc('\r', stream);
  }
  while (!(UCSR0A & (1 << UDRE0))); // Wait until the buffer is empty
  UDR0 = c;
  return 0;
}

int uart_getc(FILE *stream) {
  while (!(UCSR0A & (1 << RXC0))); // Wait until data is received
  return UDR0;
}

#endif // UARTH_H