Erik vd Zalm
12 years ago
2 changed files with 42 additions and 167 deletions
@ -1,127 +0,0 @@ |
|||
#!/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 |
|||
|
|||
The main use is for Arduino programs that read data from the circuit board described here: |
|||
http://make.rrrf.org/ts-1.0 |
|||
|
|||
Usage: python createTemperatureLookup.py [options] |
|||
|
|||
Options: |
|||
-h, --help show this help |
|||
--r0=... thermistor rating where # is the ohm rating of the thermistor at t0 (eg: 10K = 10000) |
|||
--t0=... thermistor temp rating where # is the temperature in Celsuis to get r0 (from your datasheet) |
|||
--beta=... thermistor beta rating. see http://reprap.org/bin/view/Main/MeasuringThermistorBeta |
|||
--r1=... R1 rating where # is the ohm rating of R1 (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) |
|||
--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 |
|||
""" |
|||
|
|||
from math import * |
|||
import sys |
|||
import getopt |
|||
|
|||
class Thermistor: |
|||
"Class to do the thermistor maths" |
|||
def __init__(self, r0, t0, beta, r1, r2): |
|||
self.r0 = r0 # stated resistance, e.g. 10K |
|||
self.t0 = t0 + 273.15 # temperature at stated resistance, e.g. 25C |
|||
self.beta = beta # stated beta, e.g. 3500 |
|||
self.vadc = 5.0 # ADC reference |
|||
self.vcc = 5.0 # supply voltage to potential divider |
|||
self.k = r0 * exp(-beta / self.t0) # constant part of calculation |
|||
|
|||
if r1 > 0: |
|||
self.vs = r1 * self.vcc / (r1 + r2) # effective bias voltage |
|||
self.rs = r1 * r2 / (r1 + r2) # effective bias impedance |
|||
else: |
|||
self.vs = self.vcc # effective bias voltage |
|||
self.rs = r2 # effective bias impedance |
|||
|
|||
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.rs * v / (self.vs - v) # resistance of thermistor |
|||
return (self.beta / log(r / self.k)) - 273.15 # temperature |
|||
|
|||
def setting(self, t): |
|||
"Convert a temperature into a ADC value" |
|||
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 |
|||
return round(v / self.vadc * 1024) # the ADC reading |
|||
|
|||
def main(argv): |
|||
|
|||
r0 = 10000; |
|||
t0 = 25; |
|||
beta = 3947; |
|||
r1 = 680; |
|||
r2 = 1600; |
|||
num_temps = int(20); |
|||
|
|||
try: |
|||
opts, args = getopt.getopt(argv, "h", ["help", "r0=", "t0=", "beta=", "r1=", "r2="]) |
|||
except getopt.GetoptError: |
|||
usage() |
|||
sys.exit(2) |
|||
|
|||
for opt, arg in opts: |
|||
if opt in ("-h", "--help"): |
|||
usage() |
|||
sys.exit() |
|||
elif opt == "--r0": |
|||
r0 = int(arg) |
|||
elif opt == "--t0": |
|||
t0 = int(arg) |
|||
elif opt == "--beta": |
|||
beta = int(arg) |
|||
elif opt == "--r1": |
|||
r1 = int(arg) |
|||
elif opt == "--r2": |
|||
r2 = int(arg) |
|||
|
|||
if r1: |
|||
max_adc = int(1023 * r1 / (r1 + r2)); |
|||
else: |
|||
max_adc = 1023 |
|||
increment = int(max_adc/(num_temps-1)); |
|||
|
|||
t = Thermistor(r0, t0, beta, r1, r2) |
|||
|
|||
adcs = range(1, max_adc, increment); |
|||
# adcs = [1, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 130, 150, 190, 220, 250, 300] |
|||
first = 1 |
|||
|
|||
print "// Thermistor lookup table for RepRap Temperature Sensor Boards (http://make.rrrf.org/ts)" |
|||
print "// Made with createTemperatureLookup.py (http://svn.reprap.org/trunk/reprap/firmware/Arduino/utilities/createTemperatureLookup.py)" |
|||
print "// ./createTemperatureLookup.py --r0=%s --t0=%s --r1=%s --r2=%s --beta=%s --max-adc=%s" % (r0, t0, r1, r2, beta, max_adc) |
|||
print "// r0: %s" % (r0) |
|||
print "// t0: %s" % (t0) |
|||
print "// r1: %s" % (r1) |
|||
print "// r2: %s" % (r2) |
|||
print "// beta: %s" % (beta) |
|||
print "// max adc: %s" % (max_adc) |
|||
print "#define NUMTEMPS %s" % (len(adcs)) |
|||
print "short temptable[NUMTEMPS][2] = {" |
|||
|
|||
counter = 0 |
|||
for adc in adcs: |
|||
counter = counter +1 |
|||
if counter == len(adcs): |
|||
print " {%s, %s}" % (adc, int(t.temp(adc))) |
|||
else: |
|||
print " {%s, %s}," % (adc, int(t.temp(adc))) |
|||
print "};" |
|||
|
|||
def usage(): |
|||
print __doc__ |
|||
|
|||
if __name__ == "__main__": |
|||
main(sys.argv[1:]) |
|||
Loading…
Reference in new issue