diff --git a/Marlin/scripts/create_speed_lookuptable.py b/Marlin/scripts/createSpeedLookupTable.py similarity index 100% rename from Marlin/scripts/create_speed_lookuptable.py rename to Marlin/scripts/createSpeedLookupTable.py diff --git a/Marlin/scripts/createTemperatureLookupMarlin.py b/Marlin/scripts/createTemperatureLookupMarlin.py index 01c602dffa..4f54c2833d 100755 --- a/Marlin/scripts/createTemperatureLookupMarlin.py +++ b/Marlin/scripts/createTemperatureLookupMarlin.py @@ -1,12 +1,8 @@ #!/usr/bin/python -# -# Creates a C code lookup table for doing ADC to temperature conversion -# on a microcontroller -# based on: http://hydraraptor.blogspot.com/2007/10/measuring-temperature-easy-way.html """Thermistor Value Lookup Table Generator Generates lookup to temperature values for use in a microcontroller in C format based on: -http://hydraraptor.blogspot.com/2007/10/measuring-temperature-easy-way.html +http://en.wikipedia.org/wiki/Steinhart-Hart_equation The main use is for Arduino programs that read data from the circuit board described here: http://make.rrrf.org/ts-1.0 @@ -16,85 +12,87 @@ Usage: python createTemperatureLookup.py [options] Options: -h, --help show this help --rp=... pull-up resistor - --t1=ttt:rrr low temperature temperature:resistance point (around 25C) - --t2=ttt:rrr middle temperature temperature:resistance point (around 150C) - --t3=ttt:rrr high temperature temperature:resistance point (around 250C) - --num-temps=... the number of temperature points to calculate (default: 20) + --t1=ttt:rrr low temperature temperature:resistance point (around 25 degC) + --t2=ttt:rrr middle temperature temperature:resistance point (around 150 degC) + --t3=ttt:rrr high temperature temperature:resistance point (around 250 degC) + --num-temps=... the number of temperature points to calculate (default: 36) """ from math import * import sys import getopt +"Constants" +ZERO = 273.15 # zero point of Kelvin scale +VADC = 5 # ADC voltage +VCC = 5 # supply voltage +ARES = 2**10 # 10 Bit ADC resolution +VSTEP = VADC / ARES # ADC voltage resolution +TMIN = 0 # lowest temperature in table +TMAX = 350 # highest temperature in table + class Thermistor: "Class to do the thermistor maths" def __init__(self, rp, t1, r1, t2, r2, t3, r3): - t1 = t1 + 273.15 # low temperature (25C) - r1 = r1 # resistance at low temperature - t2 = t2 + 273.15 # middle temperature (150C) - r2 = r2 # resistance at middle temperature - t3 = t3 + 273.15 # high temperature (250C) - r3 = r3 # resistance at high temperature - self.rp = rp # pull-up resistance - self.vadc = 5.0 # ADC reference - self.vcc = 5.0 # supply voltage to potential divider - a1 = log(r1) - a2 = log(r2) - a3 = log(r3) - z = a1 - a2 - y = a1 - a3 - x = 1/t1 - 1/t2 - w = 1/t1 - 1/t3 - v = pow(a1,3) - pow(a2,3) - u = pow(a1,3) - pow(a3,3) - c3 = (x-z*w/y)/(v-z*u/y) - c2 = (x-c3*v)/z - c1 = 1/t1-c3*pow(a1,3)-c2*a1 - self.c1 = c1 - self.c2 = c2 - self.c3 = c3 + l1 = log(r1) + l2 = log(r2) + l3 = log(r3) + y1 = 1.0 / (t1 + ZERO) # adjust scale + y2 = 1.0 / (t2 + ZERO) + y3 = 1.0 / (t3 + ZERO) + x = (y2 - y1) / (l2 - l1) + y = (y3 - y1) / (l3 - l1) + c = (y - x) / ((l3 - l2) * (l1 + l2 + l3)) + b = x - c * (l1**2 + l2**2 + l1*l2) + a = y1 - (b + l1**2 *c)*l1 + + if c < 0: + print "//////////////////////////////////////////////////////////////////////////////////////" + print "// WARNING: negative coefficient 'c'! Something may be wrong with the measurements! //" + print "//////////////////////////////////////////////////////////////////////////////////////" + c = -c + self.c1 = a # Steinhart-Hart coefficients + self.c2 = b + self.c3 = c + self.rp = rp # pull-up resistance - def res(self,adc): + def resol(self, adc): "Convert ADC reading into a resolution" res = self.temp(adc)-self.temp(adc+1) return res - def v(self,adc): + def voltage(self, adc): "Convert ADC reading into a Voltage" - v = adc * self.vadc / (1024 ) # convert the 10 bit ADC value to a voltage - return v + return adc * VSTEP # convert the 10 bit ADC value to a voltage - def r(self,adc): + def resist(self, adc): "Convert ADC reading into a resistance in Ohms" - v = adc * self.vadc / (1024 ) # convert the 10 bit ADC value to a voltage - r = self.rp * v / (self.vcc - v) # resistance of thermistor + r = self.rp * self.voltage(adc) / (VCC - self.voltage(adc)) # resistance of thermistor return r - def temp(self,adc): + def temp(self, adc): "Convert ADC reading into a temperature in Celcius" - v = adc * self.vadc / (1024 ) # convert the 10 bit ADC value to a voltage - r = self.rp * v / (self.vcc - v) # resistance of thermistor - lnr = log(r) - Tinv = self.c1 + (self.c2*lnr) + (self.c3*pow(lnr,3)) - return (1/Tinv) - 273.15 # temperature + l = log(self.resist(adc)) + Tinv = self.c1 + self.c2*l + self.c3* l**3) # inverse temperature + return (1/Tinv) - ZERO # temperature - def adc(self,temp): + def adc(self, temp): "Convert temperature into a ADC reading" - y = (self.c1 - (1/(temp+273.15))) / (2*self.c3) - x = sqrt(pow(self.c2 / (3*self.c3),3) + pow(y,2)) - r = exp(pow(x-y,1.0/3) - pow(x+y,1.0/3)) # resistance of thermistor - return (r / (self.rp + r)) * (1024) + x = (self.c1 - (1.0 / (temp+ZERO))) / (2*self.c3) + y = sqrt((self.c2 / (3*self.c3)**3 + x**2) + r = exp((y-x)**(1.0/3) - (y+x)**(1.0/3)) + return (r / (self.rp + r)) * ARES def main(argv): - - rp = 4700; - t1 = 25; - r1 = 100000; - t2 = 150; - r2 = 1641.9; - t3 = 250; - r3 = 226.15; - num_temps = int(36); + "Default values" + t1 = 25 # low temperature in Kelvin (25 degC) + r1 = 100000 # resistance at low temperature (10 kOhm) + t2 = 150 # middle temperature in Kelvin (150 degC) + r2 = 1641.9 # resistance at middle temperature (1.6 KOhm) + t3 = 250 # high temperature in Kelvin (250 degC) + r3 = 226.15 # resistance at high temperature (226.15 Ohm) + rp = 4700; # pull-up resistor (4.7 kOhm) + num_temps = 36; # number of entries for look-up table try: opts, args = getopt.getopt(argv, "h", ["help", "rp=", "t1=", "t2=", "t3=", "num-temps="]) @@ -102,7 +100,7 @@ def main(argv): print str(err) usage() sys.exit(2) - + for opt, arg in opts: if opt in ("-h", "--help"): usage() @@ -111,44 +109,46 @@ def main(argv): rp = int(arg) elif opt == "--t1": arg = arg.split(':') - t1 = float( arg[0]) - r1 = float( arg[1]) + t1 = float(arg[0]) + r1 = float(arg[1]) elif opt == "--t2": arg = arg.split(':') - t2 = float( arg[0]) - r2 = float( arg[1]) + t2 = float(arg[0]) + r2 = float(arg[1]) elif opt == "--t3": arg = arg.split(':') - t3 = float( arg[0]) - r3 = float( arg[1]) + t3 = float(arg[0]) + r3 = float(arg[1]) elif opt == "--num-temps": - num_temps = int(arg) + num_temps = int(arg) - max_adc = (1024 ) - 1 - min_temp = 0 - max_temp = 350 - increment = int(max_adc/(num_temps-1)); - t = Thermistor(rp, t1, r1, t2, r2, t3, r3) - tmp = (min_temp - max_temp) / (num_temps-1) - print tmp - temps = range(max_temp, min_temp + tmp, tmp); + increment = int((ARES-1)/(num_temps-1)); + step = (TMIN-TMAX) / (num_temps-1) + low_bound = t.temp(ARES-1); + up_bound = t.temp(1); + min_temp = int(TMIN if TMIN > low_bound else low_bound) + max_temp = int(TMAX if TMAX < up_bound else up_bound) + temps = range(max_temp, TMIN+step, step); print "// Thermistor lookup table for Marlin" print "// ./createTemperatureLookupMarlin.py --rp=%s --t1=%s:%s --t2=%s:%s --t3=%s:%s --num-temps=%s" % (rp, t1, r1, t2, r2, t3, r3, num_temps) - print "// Steinhart-Hart Coefficients: %.15g, %.15g, %.15g " % (t.c1, t.c2, t.c3) - print "//#define NUMTEMPS %s" % (len(temps)) + print "// Steinhart-Hart Coefficients: a=%.15g, b=%.15g, c=%.15g " % (t.c1, t.c2, t.c3) + print "// Theoretical limits of termistor: %.2f to %.2f degC" % (low_bound, up_bound) + print + print "#define NUMTEMPS %s" % (len(temps)) print "const short temptable[NUMTEMPS][2] PROGMEM = {" - counter = 0 for temp in temps: - counter = counter +1 - if counter == len(temps): - print " {(short)(%.2f*OVERSAMPLENR), %s} // v=%s r=%s res=%s C/count" % ((t.adc(temp)), temp, t.v(t.adc(temp)), t.r(t.adc(temp)),t.res(t.adc(temp))) - else: - print " {(short)(%.2f*OVERSAMPLENR), %s}, // v=%s r=%s res=%s C/count" % ((t.adc(temp)), temp, t.v(t.adc(temp)), t.r(t.adc(temp)),t.res(t.adc(temp))) + adc = t.adc(temp) + print " { (short) (%7.2f * OVERSAMPLENR ), %4s }%s // v=%.3f\tr=%.3f\tres=%.3f degC/count" % (adc , temp, \ + ',' if temp != temps[-1] else ' ', \ + t.voltage(adc), \ + t.resist( adc), \ + t.resol( adc) \ + ) print "};" - + def usage(): print __doc__