controller_fan: Add support for a fan cooling the controller-board (#1070)

Whenever a stepper driver or a heater becomes active, it is desirable to turn on a fan cooling the associated parts on the controller board. This module implements such a fan that turns on whenever a stepper or specified heater turns on, decelerates to a configurable speed when all of the watched parts turn off, and returns to an off-speed, when a user-defined timeout is met.

Signed-off-by: Nils Friedchen <Nils.Friedchen@googlemail.com>

config/example-extras.cfg

@@ -414,6 +414,36 @@
 #   is 1.0
 
 
+# Controller cooling fan. A "controller fan" is a fan that will be
+# enabled whenever its associated heater or any configured stepper
+# driver is active. The fan will stop, whenever an idle_timeout is
+# reached to ensure no overheating will occur after deactivating a
+# watched component.
+#[controller_fan]
+#pin:
+#max_power:
+#shutdown_speed:
+#cycle_time:
+#hardware_pwm:
+#kick_start_time:
+#   See the "fan" section in example.cfg for a description of the
+#   above parameters.
+#idle_timeout:
+#   The ammount of time (in seconds) after a stepper driver or heater
+#   was active and the fan should be kept running. The default
+#   is 30 seconds.
+#idle_speed:
+#   The fan speed (expressed as a value from 0.0 to 1.0) that the fan
+#   will be set to when a heater or stepper driver was active and before
+#   the idle_timeout is reached. This must be greater or equal
+#   max_power. The default is max_power
+#heater:
+#   Name of the config section defining the heater that this fan is
+#   associated with. If a comma separated list of heater names is
+#   provided here, then the fan will be enabled when any of the given
+#   heaters are enabled. The default is "extruder".
+
+
 # Temperature-triggered cooling fans (one may define any number of
 # sections with a "temperature_fan" prefix). A "temperature fan" is a
 # fan that will be enabled whenever its associated sensor is above a