temperature_sensor: Add generic temperature sensor support

Signed-off-by: Douglas Hammond <wizhippo@gmail.com>
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/example-extras.cfg

@@ -1325,7 +1325,22 @@
 #min_extrude_temp:
 #min_temp:
 #max_temp:
-#   See the example.cfg for the definition of the above parameters.
+#   See the heater section in example.cfg for the definition of the
+#   above parameters.
+
+# Temperature sensors. One can define any number of temperature
+# sensors. Their values are reported via the M105 command.
+#[temperature_sensor my_sensor]
+#sensor_type:
+#sensor_pin:
+#min_temp:
+#max_temp:
+#   See the heater section in example.cfg for the definition of the
+#   above parameters.
+#gcode_id:
+#   See the heater_generic section above for the definition of this
+#   parameter.
+
 
 # Pause/Resume functionality with support of position capture and restore
 #[pause_resume]

klippy/extras/temperature_sensor.py

@@ -0,0 +1,27 @@
+# Support generic temperature sensors
+#
+# Copyright (C) 2019  Kevin O'Connor <kevin@koconnor.net>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+
+KELVIN_TO_CELCIUS = -273.15
+
+class PrinterSensorGeneric:
+    def __init__(self, config):
+        self.printer = config.get_printer()
+        self.sensor = self.printer.lookup_object('heater').setup_sensor(config)
+        self.min_temp = config.getfloat('min_temp', KELVIN_TO_CELCIUS,
+                                        minval=KELVIN_TO_CELCIUS)
+        self.max_temp = config.getfloat('max_temp', 99999999.9,
+                                        above=self.min_temp)
+        self.sensor.setup_minmax(self.min_temp, self.max_temp)
+        self.sensor.setup_callback(self.temperature_callback)
+        self.printer.lookup_object('heater').register_sensor(config, self)
+        self.last_temp = 0.
+    def temperature_callback(self, read_time, temp):
+        self.last_temp = temp
+    def get_temp(self, eventtime):
+        return self.last_temp, 0.
+
+def load_config_prefix(config):
+    return PrinterSensorGeneric(config)

test/klippy/temperature.cfg

@@ -125,11 +125,7 @@ resistance2: 2000
 temperature3: 250
 resistance3: 3000
 
-[temperature_fan test_custom_resistance_adc]
+[temperature_sensor test_custom_resistance_adc]
-pin: ar17
-min_temp: 0
-max_temp: 100
-control: watermark
 sensor_type: my_custom_resistance_adc
 sensor_pin: analog5