'Take the ADC readings, for each of the four channels, and convert them to
'actual temperatures.
'Use the Steinhart-Hart equation to do this.
'Once have the temperatures from the ACD voltage readings, then PACK the
'temperature into a 2 byte values.
'This is a "Scaled" or "Packed" value.
'This makes it easy to store, and easy to transmit to micro#2.
'Note Well: The thermistor data sheet gives enough data that this conversion
'from resistance, to voltage, to temperature can be done in any of three methods.
'Method 1:
'The data sheet gives the resistance at each of 10 'C intervals.
'One can have a simple table and do linear interpolation within that 10'C span.
'This converts -10 to + 70 'C into 10, piecewise linear curves.
'Method 2:
'Use the SH-H equation using the a, b, and c coefficients.
'This is very calculation intensive.
'Method 3:
'Use the B, (Beta), and known data point form of the SH-H equation to do the
'temperature converions.
'We will use this method below:
'On entry have the already 4 sample averaged ADC values in the ADCData() array.
'The First slot for each channel's data has the averaged values.
'On exit it is replaced with the packet form of the Temperature.
'T in 'C = [Beta / [(ln(ADC/(1024-ADC))) + (Beta/Tamb)] ] - Tzero
'Beta is from the data sheet, 3947
'Tzero is 273, Zero degrees Kelvin converted to 'C
'Tamb = Temp @ 25'C --> 273 + 25 in degrees Kelvin
'R = 10000 at 25 'C from the data sheet
'Beta/Tamb = 13.244566
'Need to convert the first four values of the ADCData() array:
'This is a SLOW routine, it does a lot of Single's type math,and a Ln().
'It must do this process four times, once for each data channel's
'average ADC reading.
For Convlp = 1 To 4
'For each of the 4 thermistor channels, convert the Avg ADC to 'C
Ttmp = Adcdata(convlp) 'Get the Avg ADC Reading
Tntc = 1024.0 - Ttmp
Tntc = Ttmp / Tntc
Tntc = Log(tntc)
Tntc = Tntc + 13.244566
Tntc = 3947.0 / Tntc
Tntc = Tntc - 273.0 'Now have the Temperature in 'C, single type
'Now round up by 0.05 'C to the nearest 0.1 'C
Tntc = Tntc + 0.05
'Now convert single to "packed temp".
'Range -10 to + 70 'C in 0.1 'C steps -> 0 to 800
'To convert, first add 10, then multiply by 10.
Tntc = Tntc + 10.0
Tntc = Tntc * 10.0
'Now convert the scaled temperature from Single to Word type
'This will fit in 2 Bytes, and this removes the fractional part of the
'temperature.
Tpack = Tntc 'Scaled, (packed) Temp, Word type
'Now Store it back where we obtained the Avg ADC Reading
Adcdata(convlp) = Tpack 'Resave the Temperature
'Now do the remaining thermistor's data
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