diff options
| -rw-r--r-- | config/example.cfg | 3 | ||||
| -rw-r--r-- | klippy/heater.py | 22 |
2 files changed, 21 insertions, 4 deletions
diff --git a/config/example.cfg b/config/example.cfg index 71ac0563..4bb805db 100644 --- a/config/example.cfg +++ b/config/example.cfg @@ -176,7 +176,8 @@ heater_pin: ar10 # periods) to the heater. The default is 1.0. sensor_type: EPCOS 100K B57560G104F # Type of sensor - this may be "EPCOS 100K B57560G104F", "ATC -# Semitec 104GT-2", or "AD595". This parameter must be provided. +# Semitec 104GT-2", "NTC 100K beta 3950", or "AD595". This parameter +# must be provided. sensor_pin: analog13 # Analog input pin connected to the sensor. This parameter must be # provided. diff --git a/klippy/heater.py b/klippy/heater.py index 8d1e658e..cb915d8a 100644 --- a/klippy/heater.py +++ b/klippy/heater.py @@ -41,11 +41,25 @@ class Thermistor: def calc_adc(self, temp): temp -= KELVIN_TO_CELCIUS temp_inv = 1./temp - y = (self.c1 - temp_inv) / (2. * self.c3) - x = math.sqrt(math.pow(self.c2 / (3.*self.c3), 3.) + math.pow(y, 2.)) - r = math.exp(math.pow(x-y, 1./3.) - math.pow(x+y, 1./3.)) + if self.c3: + y = (self.c1 - temp_inv) / (2. * self.c3) + x = math.sqrt(math.pow(self.c2 / (3.*self.c3), 3.) + math.pow(y, 2.)) + r = math.exp(math.pow(x-y, 1./3.) - math.pow(x+y, 1./3.)) + else: + r = math.exp((temp_inv - self.c1) / self.c2) return r / (self.pullup + r) +# Thermistor calibrated from one temp measurement and its beta +class ThermistorBeta(Thermistor): + def __init__(self, config, params): + self.pullup = config.getfloat('pullup_resistor', 4700., above=0.) + # Calculate Steinhart-Hart coefficents from beta + inv_t1 = 1. / (params['t1'] - KELVIN_TO_CELCIUS) + ln_r1 = math.log(params['r1']) + self.c3 = 0. + self.c2 = 1. / params['beta'] + self.c1 = inv_t1 - self.c2 * ln_r1 + # Linear style conversion chips calibrated with two temp measurements class Linear: def __init__(self, config, params): @@ -66,6 +80,8 @@ Sensors = { "ATC Semitec 104GT-2": { 'class': Thermistor, 't1': 20., 'r1': 126800., 't2': 150., 'r2': 1360., 't3': 300., 'r3': 80.65 }, + "NTC 100K beta 3950": { + 'class': ThermistorBeta, 't1': 25., 'r1': 100000., 'beta': 3950. }, "AD595": { 'class': Linear, 't1': 25., 'v1': .25, 't2': 300., 'v2': 3.022 }, } |