comparison: createTemperatureLookup.py
createTemperatureLookup.py
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| 1 #!/usr/bin/python | |
| 2 # | |
| 3 # Creates a C code lookup table for doing ADC to temperature conversion | |
| 4 # on a microcontroller | |
| 5 # based on: http://hydraraptor.blogspot.com/2007/10/measuring-temperature-easy-way.html | |
| 6 """Thermistor Value Lookup Table Generator | |
| 7 | |
| 8 Generates lookup to temperature values for use in a microcontroller in C format based on: | |
| 9 http://hydraraptor.blogspot.com/2007/10/measuring-temperature-easy-way.html | |
| 10 | |
| 11 The main use is for Arduino programs that read data from the circuit board described here: | |
| 12 http://make.rrrf.org/ts-1.0 | |
| 13 | |
| 14 Usage: python createTemperatureLookup.py [options] | |
| 15 | |
| 16 Options: | |
| 17 -h, --help show this help | |
| 18 --r0=... thermistor rating where # is the ohm rating of the thermistor at t0 (eg: 10K = 10000) | |
| 19 --t0=... thermistor temp rating where # is the temperature in Celsuis to get r0 (from your datasheet) | |
| 20 --beta=... thermistor beta rating. see http://reprap.org/bin/view/Main/MeasuringThermistorBeta | |
| 21 --r1=... R1 rating where # is the ohm rating of R1 (eg: 10K = 10000) | |
| 22 --r2=... R2 rating where # is the ohm rating of R2 (eg: 10K = 10000) | |
| 23 --num-temps=... the number of temperature points to calculate (default: 20) | |
| 24 --max-adc=... the max ADC reading to use. if you use R1, it limits the top value for the thermistor circuit, and thus the possible range of ADC values | |
| 25 """ | |
| 26 | |
| 27 from math import * | |
| 28 import sys | |
| 29 import getopt | |
| 30 | |
| 31 class Thermistor: | |
| 32 "Class to do the thermistor maths" | |
| 33 def __init__(self, r0, t0, beta, r1, r2): | |
| 34 self.r0 = r0 # stated resistance, e.g. 10K | |
| 35 self.t0 = t0 + 273.15 # temperature at stated resistance, e.g. 25C | |
| 36 self.beta = beta # stated beta, e.g. 3500 | |
| 37 self.vadc = 5.0 # ADC reference | |
| 38 self.vcc = 5.0 # supply voltage to potential divider | |
| 39 self.k = r0 * exp(-beta / self.t0) # constant part of calculation | |
| 40 | |
| 41 if r1 > 0: | |
| 42 self.vs = r1 * self.vcc / (r1 + r2) # effective bias voltage | |
| 43 self.rs = r1 * r2 / (r1 + r2) # effective bias impedance | |
| 44 else: | |
| 45 self.vs = self.vcc # effective bias voltage | |
| 46 self.rs = r2 # effective bias impedance | |
| 47 | |
| 48 def temp(self,adc): | |
| 49 "Convert ADC reading into a temperature in Celcius" | |
| 50 v = adc * self.vadc / 1024 # convert the 10 bit ADC value to a voltage | |
| 51 r = self.rs * v / (self.vs - v) # resistance of thermistor | |
| 52 return (self.beta / log(r / self.k)) - 273.15 # temperature | |
| 53 | |
| 54 def setting(self, t): | |
| 55 "Convert a temperature into a ADC value" | |
| 56 r = self.r0 * exp(self.beta * (1 / (t + 273.15) - 1 / self.t0)) # resistance of the thermistor | |
| 57 v = self.vs * r / (self.rs + r) # the voltage at the potential divider | |
| 58 return round(v / self.vadc * 1024) # the ADC reading | |
| 59 | |
| 60 def main(argv): | |
| 61 | |
| 62 r0 = 10000; | |
| 63 t0 = 25; | |
| 64 beta = 3947; | |
| 65 r1 = 680; | |
| 66 r2 = 1600; | |
| 67 num_temps = int(20); | |
| 68 | |
| 69 try: | |
| 70 opts, args = getopt.getopt(argv, "h", ["help", "r0=", "t0=", "beta=", "r1=", "r2="]) | |
| 71 except getopt.GetoptError: | |
| 72 usage() | |
| 73 sys.exit(2) | |
| 74 | |
| 75 for opt, arg in opts: | |
| 76 if opt in ("-h", "--help"): | |
| 77 usage() | |
| 78 sys.exit() | |
| 79 elif opt == "--r0": | |
| 80 r0 = int(arg) | |
| 81 elif opt == "--t0": | |
| 82 t0 = int(arg) | |
| 83 elif opt == "--beta": | |
| 84 beta = int(arg) | |
| 85 elif opt == "--r1": | |
| 86 r1 = int(arg) | |
| 87 elif opt == "--r2": | |
| 88 r2 = int(arg) | |
| 89 | |
| 90 if r1: | |
| 91 max_adc = int(1023 * r1 / (r1 + r2)); | |
| 92 else: | |
| 93 max_adc = 1023 | |
| 94 increment = int(max_adc/(num_temps-1)); | |
| 95 | |
| 96 t = Thermistor(r0, t0, beta, r1, r2) | |
| 97 | |
| 98 adcs = range(1, max_adc, increment); | |
| 99 # adcs = [1, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 130, 150, 190, 220, 250, 300] | |
| 100 first = 1 | |
| 101 | |
| 102 print "// Thermistor lookup table for RepRap Temperature Sensor Boards (http://make.rrrf.org/ts)" | |
| 103 print "// Made with createTemperatureLookup.py (http://svn.reprap.org/trunk/reprap/firmware/Arduino/utilities/createTemperatureLookup.py)" | |
| 104 print "// ./createTemperatureLookup.py --r0=%s --t0=%s --r1=%s --r2=%s --beta=%s --max-adc=%s" % (r0, t0, r1, r2, beta, max_adc) | |
| 105 print "// r0: %s" % (r0) | |
| 106 print "// t0: %s" % (t0) | |
| 107 print "// r1: %s" % (r1) | |
| 108 print "// r2: %s" % (r2) | |
| 109 print "// beta: %s" % (beta) | |
| 110 print "// max adc: %s" % (max_adc) | |
| 111 print "#define NUMTEMPS %s" % (len(adcs)) | |
| 112 print "short temptable[NUMTEMPS][2] = {" | |
| 113 | |
| 114 counter = 0 | |
| 115 for adc in adcs: | |
| 116 counter = counter +1 | |
| 117 if counter == len(adcs): | |
| 118 print " {%s, %s}" % (adc, int(t.temp(adc))) | |
| 119 else: | |
| 120 print " {%s, %s}," % (adc, int(t.temp(adc))) | |
| 121 print "};" | |
| 122 | |
| 123 def usage(): | |
| 124 print __doc__ | |
| 125 | |
| 126 if __name__ == "__main__": | |
| 127 main(sys.argv[1:]) |
