diff options
Diffstat (limited to 'klippy/extras/thermistor.py')
| -rw-r--r-- | klippy/extras/thermistor.py | 79 |
1 files changed, 46 insertions, 33 deletions
diff --git a/klippy/extras/thermistor.py b/klippy/extras/thermistor.py index db26b50c..db1288e5 100644 --- a/klippy/extras/thermistor.py +++ b/klippy/extras/thermistor.py @@ -8,18 +8,20 @@ from . import adc_temperature KELVIN_TO_CELSIUS = -273.15 + # Analog voltage to temperature converter for thermistors class Thermistor: def __init__(self, pullup, inline_resistor): self.pullup = pullup self.inline_resistor = inline_resistor - self.c1 = self.c2 = self.c3 = 0. + self.c1 = self.c2 = self.c3 = 0.0 + def setup_coefficients(self, t1, r1, t2, r2, t3, r3, name=""): # Calculate Steinhart-Hart coefficients from temp measurements. # Arrange samples as 3 linear equations and solve for c1, c2, and c3. - inv_t1 = 1. / (t1 - KELVIN_TO_CELSIUS) - inv_t2 = 1. / (t2 - KELVIN_TO_CELSIUS) - inv_t3 = 1. / (t3 - KELVIN_TO_CELSIUS) + inv_t1 = 1.0 / (t1 - KELVIN_TO_CELSIUS) + inv_t2 = 1.0 / (t2 - KELVIN_TO_CELSIUS) + inv_t3 = 1.0 / (t3 - KELVIN_TO_CELSIUS) ln_r1 = math.log(r1) ln_r2 = math.log(r2) ln_r3 = math.log(r3) @@ -29,79 +31,90 @@ class Thermistor: ln_r12, ln_r13 = ln_r1 - ln_r2, ln_r1 - ln_r3 ln3_r12, ln3_r13 = ln3_r1 - ln3_r2, ln3_r1 - ln3_r3 - self.c3 = ((inv_t12 - inv_t13 * ln_r12 / ln_r13) - / (ln3_r12 - ln3_r13 * ln_r12 / ln_r13)) - if self.c3 <= 0.: + self.c3 = (inv_t12 - inv_t13 * ln_r12 / ln_r13) / ( + ln3_r12 - ln3_r13 * ln_r12 / ln_r13 + ) + if self.c3 <= 0.0: beta = ln_r13 / inv_t13 - logging.warning("Using thermistor beta %.3f in heater %s", - beta, name) + logging.warning("Using thermistor beta %.3f in heater %s", beta, name) self.setup_coefficients_beta(t1, r1, beta) return self.c2 = (inv_t12 - self.c3 * ln3_r12) / ln_r12 self.c1 = inv_t1 - self.c2 * ln_r1 - self.c3 * ln3_r1 + def setup_coefficients_beta(self, t1, r1, beta): # Calculate equivalent Steinhart-Hart coefficients from beta - inv_t1 = 1. / (t1 - KELVIN_TO_CELSIUS) + inv_t1 = 1.0 / (t1 - KELVIN_TO_CELSIUS) ln_r1 = math.log(r1) - self.c3 = 0. - self.c2 = 1. / beta + self.c3 = 0.0 + self.c2 = 1.0 / beta self.c1 = inv_t1 - self.c2 * ln_r1 + def calc_temp(self, adc): # Calculate temperature from adc - adc = max(.00001, min(.99999, adc)) + adc = max(0.00001, min(0.99999, adc)) r = self.pullup * adc / (1.0 - adc) ln_r = math.log(r - self.inline_resistor) inv_t = self.c1 + self.c2 * ln_r + self.c3 * ln_r**3 - return 1.0/inv_t + KELVIN_TO_CELSIUS + return 1.0 / inv_t + KELVIN_TO_CELSIUS + def calc_adc(self, temp): # Calculate adc reading from a temperature if temp <= KELVIN_TO_CELSIUS: - return 1. - inv_t = 1. / (temp - KELVIN_TO_CELSIUS) + return 1.0 + inv_t = 1.0 / (temp - KELVIN_TO_CELSIUS) if self.c3: # Solve for ln_r using Cardano's formula - y = (self.c1 - inv_t) / (2. * self.c3) - x = math.sqrt((self.c2 / (3. * self.c3))**3 + y**2) - ln_r = math.pow(x - y, 1./3.) - math.pow(x + y, 1./3.) + y = (self.c1 - inv_t) / (2.0 * self.c3) + x = math.sqrt((self.c2 / (3.0 * self.c3)) ** 3 + y**2) + ln_r = math.pow(x - y, 1.0 / 3.0) - math.pow(x + y, 1.0 / 3.0) else: ln_r = (inv_t - self.c1) / self.c2 r = math.exp(ln_r) + self.inline_resistor return r / (self.pullup + r) + # Create an ADC converter with a thermistor def PrinterThermistor(config, params): - pullup = config.getfloat('pullup_resistor', 4700., above=0.) - inline_resistor = config.getfloat('inline_resistor', 0., minval=0.) + pullup = config.getfloat("pullup_resistor", 4700.0, above=0.0) + inline_resistor = config.getfloat("inline_resistor", 0.0, minval=0.0) thermistor = Thermistor(pullup, inline_resistor) - if 'beta' in params: - thermistor.setup_coefficients_beta( - params['t1'], params['r1'], params['beta']) + if "beta" in params: + thermistor.setup_coefficients_beta(params["t1"], params["r1"], params["beta"]) else: thermistor.setup_coefficients( - params['t1'], params['r1'], params['t2'], params['r2'], - params['t3'], params['r3'], name=config.get_name()) + params["t1"], + params["r1"], + params["t2"], + params["r2"], + params["t3"], + params["r3"], + name=config.get_name(), + ) return adc_temperature.PrinterADCtoTemperature(config, thermistor) + # Custom defined thermistors from the config file class CustomThermistor: def __init__(self, config): self.name = " ".join(config.get_name().split()[1:]) t1 = config.getfloat("temperature1", minval=KELVIN_TO_CELSIUS) - r1 = config.getfloat("resistance1", minval=0.) - beta = config.getfloat("beta", None, above=0.) + r1 = config.getfloat("resistance1", minval=0.0) + beta = config.getfloat("beta", None, above=0.0) if beta is not None: - self.params = {'t1': t1, 'r1': r1, 'beta': beta} + self.params = {"t1": t1, "r1": r1, "beta": beta} return t2 = config.getfloat("temperature2", minval=KELVIN_TO_CELSIUS) - r2 = config.getfloat("resistance2", minval=0.) + r2 = config.getfloat("resistance2", minval=0.0) t3 = config.getfloat("temperature3", minval=KELVIN_TO_CELSIUS) - r3 = config.getfloat("resistance3", minval=0.) + r3 = config.getfloat("resistance3", minval=0.0) (t1, r1), (t2, r2), (t3, r3) = sorted([(t1, r1), (t2, r2), (t3, r3)]) - self.params = {'t1': t1, 'r1': r1, 't2': t2, 'r2': r2, - 't3': t3, 'r3': r3} + self.params = {"t1": t1, "r1": r1, "t2": t2, "r2": r2, "t3": t3, "r3": r3} + def create(self, config): return PrinterThermistor(config, self.params) + def load_config_prefix(config): thermistor = CustomThermistor(config) pheaters = config.get_printer().load_object(config, "heaters") |