josh
/
Teacup_Firmware
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

More features for createTemperatureLookup.py. 

Contribution by DaveX, see
http://forums.reprap.org/read.php?147,33082,165159#msg-165159
This commit is contained in:
Markus Hitter 2012-11-09 19:29:02 +01:00
parent 33b550e227
commit fd019f350f
1 changed files with 65 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

94
createTemperatureLookup.py
View File

@ -8,14 +8,15 @@
# temps are now in 14.2 fixed point notation (i.e. measured in quarter-degrees) # temps are now in 14.2 fixed point notation (i.e. measured in quarter-degrees)
# temps are not permitted to be negative (BUG:may result in numtemps fewer than requested) # temps are not permitted to be negative (BUG:may result in numtemps fewer than requested)
# bugfix: --num-temps command line option works. # bugfix: --num-temps command line option works.
# 2012-11-08, DaveX: Modified to add --vcc=, --min_adc=, --mult and to print per-ADC comments
"""Thermistor Value Lookup Table Generator """Thermistor Value Lookup Table Generator
Generates lookup to temperature values for use in a microcontroller in C format based on: 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://hydraraptor.blogspot.com/2007/10/measuring-temperature-easy-way.html
The main use is for Arduino programs that read data from the circuit board described here: The main use is for Arduino programs that read data from the circuit board described here:
http://make.rrrf.org/ts-1.0 http://make.rrrf.org/ts-1.0 or http://reprap.org/wiki/Temperature_Sensor_2_0
Usage: python createTemperatureLookup.py [options] Usage: python createTemperatureLookup.py [options]
@ -28,6 +29,9 @@ Options:
--r2=... R2 rating where # is the ohm rating of R2 (eg: 10K = 10000) --r2=... R2 rating where # is the ohm rating of R2 (eg: 10K = 10000)
--num-temps=... the number of temperature points to calculate (default: 20) --num-temps=... the number of temperature points to calculate (default: 20)
--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 --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
--min-adc=... the minimum ADC reading to use.
--vadc=... ADC reference voltage (high leg of R2) same as Vcc
--vcc=... Voltage divider supply (high leg of R2) Unused
It is suggested to generate more values than you need, and delete some of the ones in the ranges It is suggested to generate more values than you need, and delete some of the ones in the ranges
that aren't interesting. This will improve accuracy in the temperature ranges that are important to you. that aren't interesting. This will improve accuracy in the temperature ranges that are important to you.
@ -39,30 +43,38 @@ import getopt
class Thermistor: class Thermistor:
"Class to do the thermistor maths" "Class to do the thermistor maths"
def __init__(self, r0, t0, beta, r1, r2): def __init__(self, r0, t0, beta, r1, r2,vcc,vadc):
self.r0 = r0 # stated resistance, e.g. 10K self.r0 = r0 # stated resistance, e.g. 10K
self.t0 = t0 + 273.15 # temperature at stated resistance, e.g. 25C self.t0 = t0 + 273.15 # temperature at stated resistance, e.g. 25C
self.beta = beta # stated beta, e.g. 3500 self.beta = beta # stated beta, e.g. 3500
self.vadc = 5.0 # ADC reference self.vadc = vadc # ADC reference
self.vcc = 5.0 # supply voltage to potential divider self.vcc = vcc # supply voltage to potential divider
self.k = r0 * exp(-beta / self.t0) # constant part of calculation self.k = r0 * exp(-beta / self.t0) # constant part of calculation
if r1 > 0: if r1 > 0:
self.vs = r1 * self.vcc / (r1 + r2) # effective bias voltage self.vs = r1 * self.vadc / (r1 + r2) # effective bias voltage
self.rs = r1 * r2 / (r1 + r2) # effective bias impedance self.rs = r1 * r2 / (r1 + r2) # effective bias impedance
else: else:
self.vs = self.vcc # effective bias voltage self.vs = self.vadc # effective bias voltage
self.rs = r2 # effective bias impedance self.rs = r2 # effective bias impedance
def temp(self,adc): def temp(self,adc):
"Convert ADC reading into a temperature in Celcius" "Convert ADC reading into a temperature in Celcius"
v = adc * self.vadc / 1024 # convert the 10 bit ADC value to a voltage v = adc * self.vadc / 1024 # convert the 10 bit ADC value to a voltage
r = self.rs * v / (self.vs - v) # resistance of thermistor r = self.rs * v / (self.vs - v) # resistance of thermistor
return (self.beta / log(r / self.k)) - 273.15 # temperature try:
return (self.beta / log(r / self.k)) - 273.15 # temperature
except:
print "// error for ADC={adc}, {v},{r}".format(adc=adc, v=v,r=r)
return 0
def resistance(self, t):
"Convert a temperature into a thermistor resistance"
return self.r0 * exp(self.beta * (1 / (t + 273.15) - 1 / self.t0)) # resistance of the thermistor
def setting(self, t): def setting(self, t):
"Convert a temperature into a ADC value" "Convert a temperature into a ADC value"
r = self.r0 * exp(self.beta * (1 / (t + 273.15) - 1 / self.t0)) # resistance of the thermistor r = self.r0 * exp(self.beta * (1 / (t + 273.15) - 1 / self.t0)) # resistance of the thermistor
v = self.vs * r / (self.rs + r) # the voltage at the potential divider v = self.vs * r / (self.rs + r) # the voltage at the potential divider
return round(v / self.vadc * 1024) # the ADC reading return round(v / self.vadc * 1024) # the ADC reading
@ -75,13 +87,17 @@ def main(argv):
r2 = 1600; r2 = 1600;
num_temps = int(20); num_temps = int(20);
max_adc = int(1023); max_adc = int(1023);
min_adc = int(1);
vadc=5.0
vcc=5.0
mult=4
try: try:
opts, args = getopt.getopt(argv, "h", ["help", "r0=", "t0=", "beta=", "r1=", "r2=", "max-adc=", "num-temps="]) opts, args = getopt.getopt(argv, "h", ["help", "r0=", "t0=", "beta=", "r1=", "r2=", "max-adc=", "min-adc=", "num-temps=", "vcc=","vadc=","multiplier="])
except getopt.GetoptError: except getopt.GetoptError:
usage() usage()
sys.exit(2) sys.exit(2)
for opt, arg in opts: for opt, arg in opts:
if opt in ("-h", "--help"): if opt in ("-h", "--help"):
usage() usage()
@ -98,28 +114,41 @@ def main(argv):
r2 = int(arg) r2 = int(arg)
elif opt == "--max-adc": elif opt == "--max-adc":
max_adc = int(arg) max_adc = int(arg)
elif opt == "--min-adc":
min_adc = int(arg)
elif opt == "--num-temps": elif opt == "--num-temps":
num_temps = int(arg) num_temps = int(arg)
elif opt == "--vadc":
increment = int(max_adc/(num_temps-1)); vadc = float(arg)
elif opt == "--vcc":
t = Thermistor(r0, t0, beta, r1, r2) vcc = float(arg)
elif opt == "--multiplier":
mult = float(arg)
if r1:
max_adc = int(1023. * r1 / (r1 + r2))
else:
max_adc = 1023
adcs = range(1, max_adc, increment); increment = int((max_adc-min_adc)/(num_temps-1));
t = Thermistor(r0, t0, beta, r1, r2, vcc, vadc)
adcs = range(min_adc, max_adc, increment);
adcs.append(max_adc)
# adcs = [1, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 130, 150, 190, 220, 250, 300] # adcs = [1, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 130, 150, 190, 220, 250, 300]
first = 1
#Chop of negative temperatures (as we're using a unsigned 16-bit value for temp) #Chop of negative temperatures (as we're using a unsigned 16-bit value for temp)
for i in range(0,len(adcs)): for i in range(0,len(adcs)):
if int(t.temp(adcs[i])*4) < 0: if int(t.temp(adcs[i])*mult) < 0:
adcs=adcs[0:i+1] adcs=adcs[0:i+1]
#Replace this with the ADC reading for 0C #Replace this with the ADC reading for 0C
adcs[i]=int(t.setting(0)) adcs[i]=int(t.setting(0))
#If the closes ADC reading to 0C is negative, convert to next highest ADC reading #If the closes ADC reading to 0C is negative, convert to next highest ADC reading
if int(t.temp(adcs[i])*4)<0: if int(t.temp(adcs[i])*mult)<0:
adcs[i] -=1 adcs[i] -=1
break break
print "// Thermistor lookup table" print "// Thermistor lookup table for RepRap Temperature Sensor Boards (http://reprap.org/wiki/Temperature_Sensor_2_0)"
print "// Made with createTemperatureLookup.py (https://github.com/triffid/Teacup_Firmware/blob/master/createTemperatureLookup.py)"
print "// (patched per https://github.com/drf5n/Teacup_Firmware/blob/Gen7/createTemperatureLookup.py)"
print "// default thermistor lookup table" print "// default thermistor lookup table"
print "// You may be able to improve the accuracy of this table in various ways." print "// You may be able to improve the accuracy of this table in various ways."
print "// 1. Measure the actual resistance of the resistor. It's \"nominally\" 4.7K, but that's ± 5%." print "// 1. Measure the actual resistance of the resistor. It's \"nominally\" 4.7K, but that's ± 5%."
@ -129,24 +158,31 @@ def main(argv):
print "// Since you'll have to do some testing to determine the correct temperature for your application anyway, you" print "// Since you'll have to do some testing to determine the correct temperature for your application anyway, you"
print "// may decide that the effort isn't worth it. Who cares if it's reporting the \"right\" temperature as long as it's" print "// may decide that the effort isn't worth it. Who cares if it's reporting the \"right\" temperature as long as it's"
print "// keeping the temperature steady enough to print, right?" print "// keeping the temperature steady enough to print, right?"
print "// ./createTemperatureLookup.py --r0=%s --t0=%s --r1=%s --r2=%s --beta=%s --max-adc=%s" % (r0, t0, r1, r2, beta, max_adc) print "// Temp*%s table from https://github.com/triffid/Teacup_Firmware/blob/master/createTemperatureLookup.py" %mult
print "// ./createTemperatureLookup.py --r0=%s --t0=%s --r1=%s --r2=%s --beta=%s --max-adc=%s --min_adc=%s --multiplier=%s --vadc=%s" % (
r0, t0, r1, r2, beta, max_adc, min_adc, mult, vadc)
print "// r0: %s" % (r0) print "// r0: %s" % (r0)
print "// t0: %s" % (t0) print "// t0: %s" % (t0)
print "// r1: %s" % (r1) print "// r1: %s (parallel with rTherm)" % (r1)
print "// r2: %s" % (r2) print "// r2: %s (series with rTherm)" % (r2)
print "// beta: %s" % (beta) print "// beta: %s" % (beta)
print "// max adc: %s" % (max_adc) print "// min adc: %s at %s V" % (min_adc, min_adc*t.vadc/1024)
print "// max adc: %s at %s V" % (max_adc, max_adc*t.vadc/1024)
print "// ADC counts from {min} to {max} by {x}".format(min=min_adc, max=max_adc, x=increment)
print "#define NUMTEMPS %s" % (len(adcs)) print "#define NUMTEMPS %s" % (len(adcs))
print "// {ADC, temp*4 }, // temp" print "// {ADC, temp*%s }, // temp Rtherm Vtherm resolution power" % (mult)
print "uint16_t temptable[NUMTEMPS][2] PROGMEM = {" print "uint16_t temptable[NUMTEMPS][2] PROGMEM = {"
counter = 0 counter = 0
for adc in adcs: for adc in adcs:
counter = counter +1 counter = counter +1
if counter == len(adcs): degC=t.temp(adc)
print " {%s, %s} // %s C" % (adc, int(t.temp(adc)*4), t.temp(adc)) resistance=t.resistance(t.temp(adc))
else: vTherm= adc*t.vadc/1024
print " {%s, %s}, // %s C" % (adc, int(t.temp(adc)*4), t.temp(adc)) ptherm= vTherm*vTherm/resistance
resolution = ( t.temp(adc-1)-t.temp(adc) if adc>1 else t.temp(adc) -t.temp(adc+1))
sep = (',' if counter != len(adcs) else ' ')
print " {%4s, %6s}%s // %7.2f C, %7.0f Ohm, %0.3f V, %0.2f C/count, %0.2fmW" % (adc, int(t.temp(adc)*mult), sep,degC, resistance,vTherm,resolution,ptherm*1000)
print "};" print "};"
def usage(): def usage():