HMC5883L – 3-Osni Digitalni kompas

Software in Assembler for PIC16F876, rutina se poziva kod starta 
;---------------------------------------------------------------------
; Inicijalizacija HCM5883L
Init_HCM5883L
	i2c_start
	movlw	0x3C		;Module address WR (0x1E)
	call	i2c_send

	movlw	0x00		;address 0x00
	call	i2c_send
 
	movlw	0x70		;8-average, 15 Hz default, normal measurement
	call	i2c_send

	movlw	0xA0		;Gain=5 (440 LSb/Gauss)
	call	i2c_send

	movlw	0x00		;Continuous-measurement mode
	call	i2c_send

	i2c_stop
	return
;---------------------------------------------------------------------

Software in Assembler for PIC16F876, rutina se poziva svake sekunde
;---------------------------------------------------------------------
; Citaj podatke iz HCM5883L - Pravac vetra
HCM5883L
	i2c_restart
	movlw	0x3D		;Module address RD (0x1E)
	call	i2c_send

;- - - - - - - - - - - - - - - - - - - - - - - -
	i2c_receive
	i2c_send_ACK
	movf	SSPBUF,W	;uzmi podatak 1
	movwf	WX_H

	i2c_receive
	i2c_send_ACK
	movf	SSPBUF,W	;uzmi podatak 2
	movwf	WX_L

	i2c_receive
	i2c_send_ACK
	movf	SSPBUF,W	;uzmi podatak 3
	movwf	WZ_H

	i2c_receive
	i2c_send_ACK
	movf	SSPBUF,W	;uzmi podatak 4
	movwf	WZ_L

	i2c_receive
	i2c_send_ACK
	movf	SSPBUF,W	;uzmi podatak 5
	movwf	WY_H

	i2c_receive
	i2c_send_NACK
	movf	SSPBUF,W	;uzmi podatak 6
	movwf	WY_L

	i2c_stop

;- - - - - - - - - - - - - - - - - - - - - - - -
	i2c_restart
	movlw	0x3C		;Module address WR (0x1E)
	call	i2c_send

	movlw	0x03		;point to first data register 0x03
	call	i2c_send

	i2c_stop
	return
;---------------------------------------------------------------------

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hmc5883.py - Python software za testiranje HMC5883

Šema RPI WS

Šema PIC WS

Data Sheet - HMC5883L.pdf

Pravac vetra

Software in C++ for Raspberry Pi
//****************************************************************************
// Calculate values – Wind Direction – Pravac vetra
//****************************************************************************
#define wdeg_offset 0 	// offset = -180...+180
...
// ----- Smer vetra (deg)
		wx = hex_val2(buf[52],buf[53],buf[54],buf[55]);
		wy = hex_val2(buf[56],buf[57],buf[58],buf[59]);
		printf("(X=%d Y=%d) ",wx,wy);
		// Offset racun
		if(wx > xmax) { xmax = wx; }
		if(wx < xmin) { xmin = wx; }
		if(wy > ymax) { ymax = wy; }
		if(wy < ymin) { ymin = wy; }
		xoff = (xmax + xmin)/2;
		yoff = (ymax + ymin)/2;
		xo = wx - xoff;
		yo = wy - yoff;
		// Gain racun
		xd = (xmax - xmin);
		yd = (ymax - ymin);
		if(xd > yd) { xgain = 1000; ygain =  (xd * 1000) / yd ; }
		else { xgain =  (yd *1000) / xd ; ygain =1000; }
		xo = (xo * xgain) / 1000;
		yo = (yo * ygain) / 1000;
		wdeg = atan_fast(xo,yo);	// X osa pokazuje SEVER
		// Deg offset racun
		wdeg = wdeg + wdeg_offset;
		if(wdeg >= 360) wdeg = wdeg -360;
		if(wdeg < 0) wdeg = wdeg + 360;
		printf("Wd=%3d' ",wdeg);
...
//----------------------------------------------------------------------
unsigned int atan_fast(signed int y, signed int x)
{
	unsigned char negflag, tempdegree, comp;
	unsigned int degree, ux, uy;
	negflag=0;
	if (x<0)
	{
		negflag+=0x01;
		x=(0-x);
	}
	ux=x;
	if (y<0)
	{
		negflag+=0x02;
		y=(0-y);
	}
	uy=y;
	if (ux>uy)
	{
		degree=(uy*45)/ux;
		negflag+=0x10;
	}
	else
	{
		degree=(ux*45)/uy;
	}
	comp=0;
	tempdegree=degree;
	if(tempdegree > 22)
	{
		if(tempdegree <= 44) comp++;
		if(tempdegree <= 41) comp++;
		if(tempdegree <= 37) comp++;
		if(tempdegree <= 32) comp++;
	}
	else
	{
		if(tempdegree >= 2) comp++;
		if(tempdegree >= 6) comp++;
		if(tempdegree >= 10) comp++;
		if(tempdegree >= 15) comp++;
	}
	degree += comp;

	if(negflag & 0x10) degree = (90-degree);
	if(negflag & 0x02)
	{
		if(negflag & 0x01)
			degree = (180 + degree);
		else
			degree = (180 - degree);
	}
	else
	{
		if(negflag & 0x01)
			degree = (360 - degree);
	}
	return (degree);
}
//----------------------------------------------------------------------

Pravac vetra - low cost sensor

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