Ultraschall Sensor im Selbstbau

[teran42]

Hallo,
hier schonmal die I2C Version mit einem Sensor:

	#define F_CPU 8000000 			//internal Oscillator CKDIV8 not set fuse low 0xXX //TODO
	#define	TWI_slaveAddress  0x10
	#define ULTRASONIC_VERSION	"Built " __DATE__ " " __TIME__	

	#define TRANSMIT_DIST01	0x01

	#include <avr/io.h>
	#include <avr/interrupt.h>
	#include <util/delay.h>
	#include "i2c-slave.h"


	void us_burst(void);
	void clear_burst(void);
	void enable_ain(void);


	#define soundspeed_per_tick 4 		//4.3mm both ways per tick

	#define BURSTS 16					// number of half periods to "ping"
	#define TIMERCOUNT 	F_CPU / 80000	// preload for timer
										// toggle the ports when reached 8 000 000 / 80 000 = 100 !!!

	register unsigned char timer_ticks asm("r10"); 	/* ticks since start of ping */
	unsigned char echo_ticks=0; 	 				/* ticks when the echo was received */
	int distance=0;
	unsigned char disp;

/* 
 * Main Program
 */
int main (void){


	unsigned char command, active;

  	// Own TWI slave address
  	i2c_initialize ( TWI_slaveAddress );
	sei(); 			// allow ints
	

	DDRD = 0x7f; 	// everything output

	DDRB |= (1<<PB2);   // Pin 2 Output
	DDRB |= (1<<PB3);   // Pin 3 Output
	DDRB &= ~(1<<PB1);// Pin 0 Input
	DDRB &= ~(1<<PB0);// Pin 0 Input
    PORTD = 0x7f;
	active = 0;
	while (1) {
		if (active==0) {
			echo_ticks = 0;
			timer_ticks = 0;
			us_burst();
    		enable_ain();
			active = 1;
		}
		if ((active==1) & (timer_ticks>240))
		{		
			//while ((timer_ticks<240) ){	//arbitrary end but mine can't see further
				asm("nop"); 
			clear_burst();
			active = 0;
			//distance = echo_ticks * soundspeed_per_tick;

			
			disp = 0;
			if (echo_ticks > 110) {
				disp |= _BV(PD6);
			}
			if (echo_ticks > 80) {
				disp |= _BV(PD5); 
			}
			if (echo_ticks > 50) {
				disp |= _BV(PD4);
			}	
			if (echo_ticks > 30) {
				disp |= _BV(PD3);
			}	
			if (echo_ticks > 20) {
				disp |= _BV(PD2);
			}	
			if (echo_ticks > 10) {
				disp |= _BV(PD1);
			}	
			if (echo_ticks > 0) {
				disp |= _BV(PD0);
			}	
			PORTD = disp;			//show it
			while (i2c_reply_ready()==0) {} //wait to put data
			if (i2c_reply_ready()){
			    i2c_rdbuf[0] = echo_ticks;		// put data in I2C buffer
   				i2c_reply_done(1);
			}
		}

	
		if (i2c_message_ready()) {
   			i2c_message_done(); // don't do anything
		}
		_delay_ms(3.0);		// wait for next run	

	}
}

/*
 * Interrupt Handler for Timer/Counter 0 
 */
ISR (TIMER0_COMPA_vect){
 timer_ticks ++;
 if (timer_ticks <=BURSTS) {	
	 PORTB ^= ((1<<PB3)|(1<<PB2)); //toggle the Pins
 }
}



/*
 * Timer 0:
 */
void us_burst(void){
	PORTB |= (_BV(PB3)); 		// ON
	PORTB &= ~(_BV(PB2)); 		// OFF
 	TCNT0  = 0x00;             	// TIMER0 preload

	TCCR0A &=  ~(_BV(COM0A1));
	TCCR0A &=  ~(_BV(COM0A0)); 	//Normale mode OC0A disconnected
	TCCR0A &=  ~(_BV(COM0B1));
	TCCR0A &=  ~(_BV(COM0B0)); 	//Normale mode OC0B disconnected
	TCCR0A |=  _BV(WGM01);		// CTC
	TCCR0B |=  _BV(CS00) ;		// use internal clock 		
								//no, we do it by hand
	//_BV(COM00) ;    			// Toggle OC0 on compare match		
	OCR0A = TIMERCOUNT;			// toggle bei erreichen 8 000 000 / 80 000 = 100 !!!
	TIMSK  |= _BV(OCIE0A);	 	// enable Output Compare 0 overflow interrupt
	GTCCR  |= _BV(PSR10);		// clear timer counter prescaler
	SREG   |= _BV(SREG_I);
	sei();                		// enable interrupts
}

void clear_burst(void) {
	//Stop it
 	TCCR0A &= ~(1<<CS00); // stopt den timer 
 	TCCR0A &= ~(1<<CS01);
 	TCCR0A &= ~(1<<CS02);
 	TIMSK &= ~(1<<OCIE0A);
	PORTB &= ~(_BV(PB2) | _BV(PB3) ); // OFF
}


/*
 * Analog compare handling
 */

ISR (ANA_COMP_vect) {
	echo_ticks = timer_ticks;
	ACSR &= ~(_BV(ACIE)); // turn interupt off, so we don't catch the next wave again	
}

void enable_ain(void) {
	ACSR &= ~(_BV(ACIE)); // interupt has to be off whenn switching ACD (see Datasheet) 
	ACSR &= ~(_BV(ACD));  // zero means turn on Analog comparator
	ACSR |=  _BV(ACIE) | _BV(ACIS0) | _BV(ACIS1); // interupt enable, trigger on rising edge
}

Dazu braucht ihr noch die usi-slave.zip, die es in folgendem Thread zum download gibt (relativ weit unten):
http://www.mikrocontroller.net/forum/read-4-290268.html

Abfragen könnt ihr den Sensor dann vom "Hauptrechner" aus wie folgt (Beispiel mit der TWI Library von Peter Fleury):

unsigned char readDist01(void) {
	unsigned char ret;
	ret = i2c_start(UltrasonicSlaveAddress+I2C_READ);
    if (ret ==1) {
		beep();
	}		
	else {
		ret = i2c_readNak();
	}
	return ret;
}

Comments welcome.

Anbei noch 2 Bilder von Work in Progress. Ich habe versucht den analogen Teil zusammen mit den Kapseln auf eine Platine outzusourcen. Kann das einer von euch mit klassischen Bauteilen (kein SMD) noch kleiner?

So long