54 lines
2.0 KiB
C
54 lines
2.0 KiB
C
/*
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These are some utility functions and variables used through the main code
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*/
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#include <Arduino.h>
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#define MS_IN_MINUTE 60000
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#define US_IN_MINUTE 60000000
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/* The following functions help determine the required fuel constant. For more information about these calculations, please refer to http://www.megamanual.com/v22manual/mfuel.htm
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Calc below are for metric inputs of temp (degrees C) and MAP (kPa) to produce kg/m3.
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*/
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int AIRDEN(int MAP, int temp)
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{
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return (1.2929 * 273.13/(temp+273.13) * MAP/101.325);
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}
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/*
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This functino retuns a pulsewidth time (in us) given the following:
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REQ_FUEL
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VE: Lookup from the main MAP vs RPM fuel table
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MAP: In KPa, read from the sensor
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GammaE: Sum of Enrichment factors (Cold start, acceleration). This is a multiplication factor (Eg to add 10%, this should be 110)
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injOpen: Injector open time. The time the injector take to open in uS
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*/
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int PW(int REQ_FUEL, byte VE, byte MAP, int GammaE, int injOpen)
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{
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//Standard float version of the calculation
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//return (REQ_FUEL * (float)(VE/100.0) * (float)(MAP/100.0) * (float)(GammaE/100.0) + injOpen);
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//100% float free version, does sacrifice a little bit of accuracy. Accuracy loss is in the order of 0.1ms (100uS)
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int iVE = ((int)VE << 7) / 100;
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int iMAP = ((int)MAP << 7) / 100;
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int iGammaE = (GammaE << 7) / 100;
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unsigned long intermediate = ((long)REQ_FUEL * (long)iVE) >>7; //Need to use an intermediate value to avoid overflowing the long
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intermediate = (intermediate * iMAP) >> 7;
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intermediate = (intermediate * iGammaE) >> 7;
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return (int)intermediate + injOpen;
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}
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/* Determine the Gamma Enrichment number. Forumla borrowed from MS2 manual... may be skipped/simplified for arduino!
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WARMUP: Warmup Correction
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O2_CLOSED: Feedback from Closed Loop Operation
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AIRTEMP: Air Temp correction <-- Skip?
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BARO: Barometric Correction <-- Skip?
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*/
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int GammaE( int WARMUP, int O2_CLOSED, int AIRTEMP, int BARO)
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{
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return (WARMUP/100) * (O2_CLOSED/100) * (AIRTEMP/100) * (BARO/100);
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}
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