SRV05 Ultraschallsensor

/*

 * SRF05.c

 *

 * Created: 08.03.2016 11:36:49

 *  Author: Admin

 */ 

#include "SRF05.h"

#include "global.h"

#include "EDIP.h"

#include "uart.h"

#include <avr/io.h>

#include <util/delay.h>

#include <stdio.h>

#include <string.h>

#define TRIGGER PB1

#define MEASURE PD3

volatile unsigned int microseconds = 0; // to save pulse length

volatile uint8_t INT1_interrupt = 0; // to indicate whether an INT1 interrupt has already occurred

volatile uint8_t measurement_complete = 0; // is used to indicate that the measurement is complete

// Function to initialize the SRF05-Interface

void SRF05_init(void)

{

  // Setup timer 1

  TCCR1A = (1<<WGM12); // CTC Mode of Timer 1

  // (8000000 / 8 ) / 10 = 1000 -> Every 1ms

  OCR1A = 10 - 1; // Interrupt fires every 10us

  TIMSK1 |= (1<<OCIE1A); // Enable compare interrupt

  DDRB |= (1<<TRIGGER); // set trigger pin to output

  DDRD &= ~(1<<MEASURE); // set INT1 as input

  EICRA |= (ISC10) | (ISC11);

  EIMSK |= (1<<INT1);

}

// Check distance

void SRF05_Measure(void)

{

  uint16_t dist = 0;

  char distanceBuf[20];

  dist = 0; // Reset distance

  microseconds = 0; // Reset ms counter

  TCNT1 = 0; // Set timer 1 to 0

  // Trigger the SRF05 measurement

  PORTB |= (1<<TRIGGER);

  _delay_ms(1); // 1ms trigger signal

  PORTB &= ~(1<<TRIGGER);

  uart_send("Trigger\n\r", 9);

  while(measurement_complete != 1); // wait until measurement is complete

  measurement_complete = 0; // Reset

  dist = microseconds / 29  ;

  // Print distance to LCD

  sprintf(distanceBuf, "Distanz: %ucm", dist);

  LCD_clearLine(0x11);

  LCD_Puts(distanceBuf, strlen(distanceBuf), 0x00, 0x11, 'L');

}

// Interrupt for signal from SRF05

ISR(INT1_vect)

{

   // Only if there hasn't been triggered on a rising edge yet

  if(INT1_interrupt == 0)

  {

    TCCR1B |= (1<<CS11); // Start timer with prescaler 8

    EICRA |= (1<<ISC11); // Set INT1 to trigger in falling edge

    EICRA &= ~(1<<ISC10);

    INT1_interrupt = 1; // To indicate, that an interrupt has already occurred

  }

  else

  {

    TCCR1B &= ~(1<<CS11); // Stop Timer

    INT1_interrupt = 0; // Reset variable

    measurement_complete = 1; // Variable to indicate end of measurement

  }

  EIFR = (1<<INTF1);

}

//Interrupt every 10µs

ISR(TIMER1_COMPA_vect)

{

  microseconds += 10;

}