fan: Default to using software PWM

Not all hardware has PWM support and there is no compelling reason to
use hardware PWM for fans.  Change the default to use software PWM.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

config/avrsim.cfg

@@ -65,7 +65,6 @@ max_temp: 110
 
 [fan]
 pin: ar14
-hard_pwm: 1
 
 [mcu]
 serial: /tmp/pseudoserial

config/example-delta.cfg

@@ -67,7 +67,6 @@ max_temp: 130
 # Extruder print fan (omit section if fan not present)
 #[fan]
 #pin: ar9
-#hard_pwm: 1
 
 [mcu]
 serial: /dev/ttyACM0

config/example.cfg

@@ -219,11 +219,12 @@ max_temp: 110
 pin: ar14
 #   PWM output pin controlling the fan. This parameter must be
 #   provided.
-hard_pwm: 1
+#hard_pwm: 0
 #   Set this value to force hardware PWM instead of software PWM. Set
 #   to 1 to force a hardware PWM at the fastest rate; set to a higher
-#   number (eg, 1024) to force hardware PWM with the given cycle time
+#   number to force hardware PWM with the given cycle time in clock
-#   in clock ticks. The default is 128 clock ticks.
+#   ticks. The default is 0 which enables software PWM with a cycle
+#   time of 10ms.
 #kick_start_time: 0.100
 #   Time (in seconds) to run the fan at full speed when first enabling
 #   it (helps get the fan spinning). The default is 0.100 seconds.

config/makergear-m2-2012.cfg

@@ -71,7 +71,6 @@ max_temp: 100
 
 [fan]
 pin: PH5
-hard_pwm: 1
 
 [mcu]
 serial: /dev/ttyACM0

klippy/fan.py

@@ -5,6 +5,7 @@
 # This file may be distributed under the terms of the GNU GPLv3 license.
 
 FAN_MIN_TIME = 0.1
+PWM_CYCLE_TIME = 0.010
 
 class PrinterFan:
     def __init__(self, printer, config):
@@ -16,8 +17,9 @@ class PrinterFan:
         self.kick_start_time = config.getfloat('kick_start_time', 0.1)
     def build_config(self):
         pin = self.config.get('pin')
-        hard_pwm = self.config.getint('hard_pwm', 128)
+        hard_pwm = self.config.getint('hard_pwm', 0)
-        self.mcu_fan = self.printer.mcu.create_pwm(pin, hard_pwm, 0)
+        self.mcu_fan = self.printer.mcu.create_pwm(
+            pin, PWM_CYCLE_TIME, hard_pwm, 0.)
     # External commands
     def set_speed(self, print_time, value):
         value = max(0., min(1., value))

klippy/heater.py

@@ -16,6 +16,7 @@ Thermistors = {
 SAMPLE_TIME = 0.001
 SAMPLE_COUNT = 8
 REPORT_TIME = 0.300
+PWM_CYCLE_TIME = 0.100
 KELVIN_TO_CELCIUS = -273.15
 MAX_HEAT_TIME = 5.0
 AMBIENT_TEMP = 25.
@@ -55,7 +56,7 @@ class PrinterHeater:
                 heater_pin, MAX_HEAT_TIME)
         else:
             self.mcu_pwm = self.printer.mcu.create_pwm(
-                heater_pin, 0, MAX_HEAT_TIME)
+                heater_pin, PWM_CYCLE_TIME, 0, MAX_HEAT_TIME)
         self.mcu_adc = self.printer.mcu.create_adc(thermistor_pin)
         min_adc = self.calc_adc(self.max_temp)
         max_adc = self.calc_adc(self.min_temp)

klippy/mcu.py

@@ -251,7 +251,7 @@ class MCU_digital_out:
 
 class MCU_pwm:
     PWM_MAX = 255.
-    def __init__(self, mcu, pin, cycle_ticks, max_duration, hard_pwm=True):
+    def __init__(self, mcu, pin, cycle_ticks, max_duration, hard_pwm=False):
         self._mcu = mcu
         self._oid = mcu.create_oid()
         self._last_clock = 0
@@ -510,14 +510,14 @@ class MCU:
     def create_digital_out(self, pin, max_duration=2.):
         max_duration = int(max_duration * self._mcu_freq)
         return MCU_digital_out(self, pin, max_duration)
-    def create_pwm(self, pin, hard_cycle_ticks, max_duration=2.):
+    def create_pwm(self, pin, cycle_time, hard_cycle_ticks=0, max_duration=2.):
         max_duration = int(max_duration * self._mcu_freq)
         if hard_cycle_ticks:
-            return MCU_pwm(self, pin, hard_cycle_ticks, max_duration)
+            return MCU_pwm(self, pin, hard_cycle_ticks, max_duration, True)
         if hard_cycle_ticks < 0:
             return MCU_digital_out(self, pin, max_duration)
-        cycle_ticks = int(self._mcu_freq / 10.)
+        cycle_ticks = int(cycle_time * self._mcu_freq)
-        return MCU_pwm(self, pin, cycle_ticks, max_duration, hard_pwm=False)
+        return MCU_pwm(self, pin, cycle_ticks, max_duration, False)
     def create_adc(self, pin):
         return MCU_adc(self, pin)
     # Clock syncing