125 lines
2.3 KiB
C
125 lines
2.3 KiB
C
/*
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* ultrasonicSensor.c
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*
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* Created: 17-3-2021 09:47:12
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* Author : Sem
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interrupt op rising edge in echo,
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dan timer1 aanzetten -> timer1 want 16 bits en willen nauwkeurig afstand kunnen meten, en afstand kan van 2 cm tot 4 m, dus willen zeker zijn dat het past
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en interrupt zetten op falling edge in echo
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als falling edge interrupt geeft ->
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waarde uit timer1 uitlezen
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en formule gebruiken high level time * velocity (340M/S) / 2
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timer1 uitzetten
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interrupt weer op rising edge van echo zetten
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*/
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#define F_CPU 20e6
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#include <avr/io.h>
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#include <util/delay.h>
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#include <avr/interrupt.h>
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#include "lcd_control.h"
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enum interrupt_status {INTERRUPT_FALLING, INTERRUPT_RISING};
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static enum interrupt_status int_stat = INTERRUPT_RISING;
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uint16_t timer_dist = 125; // time measured by timer;
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void wait_us(unsigned int us)
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{
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for(int i = 0; i < us; i++)
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{
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_delay_us(1);
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}
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}
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void wait_ms(unsigned int ms)
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{
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for(int i = 0; i < ms; i++)
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{
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_delay_ms(1);
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}
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}
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void ultrasonic_send_pulse()
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{
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PORTG = 0x00; // 10 us low pulse
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wait_us(10);
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PORTG = 0x01;
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}
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ISR(INT0_vect)
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{
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timer_dist = 2009;
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// if the interrupt was generated on a rising edge (start sending echo)
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if (int_stat == INTERRUPT_RISING)
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{
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// set interrupt pin 0 on PORTD to falling edge
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EICRA = 0x02;
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// reset the time in timer1
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TCNT1 = 0x00;
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// set interrupt status
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int_stat = INTERRUPT_FALLING;
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} else
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// else if it was generated on a falling edge (end sending echo)
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{
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// set interrupt pin 0 on PORTD to rising edge
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EICRA = 0x03;
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// read timer1 into time_dist
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timer_dist = TCNT1;
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// set interrupt status
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int_stat = INTERRUPT_RISING;
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}
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}
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int main(void)
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{
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DDRG = 0xFF; // port g all output. pin 0 is trig, the rest is for debug
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DDRD = 0x00; // port D pin 0 on input. 0 is echo and also interrupt
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EICRA = 0x03; // interrupt PORTD on pin 0, rising edge
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EIMSK |= 0x01; // enable interrupt on pin 0 (INT0)
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TCCR1A = 0b00000000; // initialize timer1, prescaler=256
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TCCR1B = 0b00001100; // CTC compare A, RUN
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sei(); // turn on interrupt system
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init_4bits_mode();
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_delay_ms(10);
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lcd_clear();
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while (1)
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{
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ultrasonic_send_pulse();
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int distance = timer_dist * 340 / 2;
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lcd_clear();
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lcd_write_int(timer_dist);
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wait_ms(100);
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}
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}
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