Prečnik kruga sa poluloptama koje se okreću je: R = 190 mm = 0.19m
Obim kruga O = R * π = 0.5966m odgovara jednom orbtaju u minuti. 1 rpm ⇒ 0.5966m/min = 0.0099433m/s
Imamo 2 impulsa po krugu u 1rpm. Za 1 impuls imamo 0.004971667m/s = 1 / 201 m/s.
U proračunu koristimo wind_cons = 201, brzina vetra = (broj impusa u minuti) / wind_const (m/s)
//****************************************************************************
// Calibration values - WIND - Vetar
//****************************************************************************
#define wind_const 201 // 1 impuls/min = 0.004971667 m/s (2 x magnet)
... // 1 impuls/min = 201 s/m
// ----- Brzina vetra (m/s)
w = (hex_val2(buf[48],buf[49],buf[50],buf[51]));
w = w / wind_const; // brzina vetra (m/s)
printf("%3.1fm/s ",w);
...
Software in Assembler for PIC16F876, ponavlja se svakog minuta:
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;Meri srednju brzinu vetra u 1min(TMR1 - Reading a 16-bit Free-Running Timer)
movf TMR1H,W
movwf W_H
movf TMR1L,W
movwf W_L
movf TMR1H,W
subwf W_H,W
btfsc _Z
goto Nastavi_TMR1
movf TMR1H,W
movwf W_H
movf TMR1L,W
movwf W_L
Nastavi_TMR1
clrf TMR1L
clrf TMR1H
clrf TMR1L
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