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Topic: Sensirion SHTxx Library Absolute Humidity and Heat Index functions (Read 2 times) previous topic - next topic

kf4ixm

Thanks for all the input. i have tried a few things and am getting heat index readings now...

i added this...
Code: [Select]
static float calcHeatIndex = SMP_ERR;

then this under poll sensor...
Code: [Select]
calcHeatIndex = shtxx.calcHeatIndex(rhSmp, taSmp);

i also added this to convert everything from C to F...
Code: [Select]
calcHeatIndex = (calcHeatIndex * 9.0)/ 5.0 + 32.0;
    taSmp = (taSmp * 9.0)/ 5.0 + 32.0;
    tdSmp = (tdSmp * 9.0)/ 5.0 + 32.0;


then this to send the result to the serial monitor...
Code: [Select]
Serial.print("Heat Index: ");
    Serial.println(calcHeatIndex);


However, the heat index reading i get is off by about -12 degF. according to a heat index calculator found here, http://www.easysurf.cc/cnver16.htm, an air temp of 71.73 a dew point of 57.13 and a humidity of 60.08 should give a heat index of 76.05f. instead i get a heat index reading of 64.33.

i've made sure that the values were in the correct places in the "calcHeatIndex = shtxx.calcHeatIndex(rhSmp, taSmp);", if i switch the rhSmp and taSmp, it jumps up to 122degF.

Any ideas or suggestions?

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