implement rudimentary duty-cycle support

kiln/manager.py

@@ -127,6 +127,7 @@ class Profile(threading.Thread):
 		self.pid = PID.PID(Kp, Ki, Kd)
 		self.callback = callback
 		self.running = True
+		self.duty_cycle = False
 		self.start()
 
 	@property
@@ -157,11 +158,19 @@ class Profile(threading.Thread):
 					temp = self.therm.temperature.temp
 					if temp == -1:
 						continue #skip invalid temperature readings
+					elif temp - setpoint > 50:
+						self.regulator.off()
+						self.duty_cycle = True
 
-					pid_out = self.pid.update(temp)
-					if pid_out < 0: pid_out = 0
-					if pid_out > 1: pid_out = 1
-					self.regulator.set(pid_out)
+					else:
+						if self.duty_cycle:
+							self.regulator.ignite()
+							self.duty_cycle = False
+						
+						pid_out = self.pid.update(temp)
+						if pid_out < 0: pid_out = 0
+						if pid_out > 1: pid_out = 1
+						self.regulator.set(pid_out)
 
 					if self.callback is not None:
 						self.callback(temp, setpoint, pid_out)