working code with python 3

src/controller.py

@@ -12,6 +12,7 @@ __TOPIC_TEXT__ = "text"
 class Controller:
 	connected = False
 	display = None
+	last_scrollupdate = 0
 
 	def __init__(self, base_topic, mqtt_host, mqtt_port = 1883):
 
@@ -70,7 +71,10 @@ class Controller:
 		
 		
 		if message.topic.endswith(__TOPIC_TEXT__ + "/set"):
+			self.poscount = 0 #start at beginning of new text
 			self.text = msg
+			if len(self.text)==0:
+				self.text="    "
 			print("changed text to ", self.text)
 			self.mqtt.publish(self.topic + "/" + __TOPIC_TEXT__, self.text, 1 )
 
@@ -85,11 +89,12 @@ class Controller:
 		run = True
 
 		while run:
-			self.mqtt.loop()
+			self.mqtt.loop(0.1) #with block timeout
 
-			if self.display is not None:
+			if self.display is not None and time.time() > self.last_scrollupdate+self.scroll_interval:
 				self.display.print(self.text[self.poscount])
 				self.poscount += 1
 				self.poscount %= len(self.text)
-				time.sleep(self.scroll_interval)
+				self.last_scrollupdate = time.time()
+