first implementation test, untested

requirements.txt

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+paho-mqtt
+adafruit-circuitpython-ht16k33

src/controller.py

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+import subprocess
+import paho.mqtt.client as mqtt
+
+import time
+import board
+import busio
+from adafruit_ht16k33 import segments
+
+__TOPIC_BRIGHTNESS__ = "brightness"
+__TOPIC_SCROLL_INTERVAL__ = "scroll_interval"
+__TOPIC_TEXT__ = ""
+
+class Controller:
+    connected = False
+
+    def __init__(self, base_topic, mqtt_host, mqtt_port = 1883):
+
+      self.scroll_interval = 0.25
+	  self.text = ""
+	  self.poscount = 0
+		
+      # Create the I2C interface.
+      self.i2c = busio.I2C(board.SCL, board.SDA)
+
+      # Create the LED segment class.
+      # This creates a 14 segment 4 character display:
+      self.display = segments.Seg14x4(self.i2c)
+
+      # Clear the display.
+      self.display.fill(0)
+
+      # set brightness, range 0-1.0, 1.0 max brightness
+      self.display.brightness = 1.0
+
+      self.mqtt = mqtt.Client()
+      self.mqtt.on_connect = self.on_connect
+      self.mqtt.on_message = self.on_message
+      self.mqtt.on_disconnect = self.on_disconnect
+      self.mqtt.connect(mqtt_host, mqtt_port)
+      self.topic = base_topic
+     
+
+    def on_disconnect(self, client, userdata, rc):
+        print("MQTT disconnected")
+        self.connected = False
+
+    def on_message(self, client, userdata, message):
+        msg = str(message.payload.decode("utf-8"))
+        print("msg = " +  msg)
+
+        if message.topic.endswith(__TOPIC_BRIGHTNESS__ + "/set"):
+		val = float(msg)
+		if val >= 0.0 and val <=1.0:
+		  self.display.brightness = val
+		  print("changed brightness to ", self.display.brightness)
+          self.mqtt.publish(self.topic + "/" + __TOPIC_BRIGHTNESS__, self.display.brightness, 1 )
+		else:
+		  print("invalid brightness ", val)
+
+        if message.topic.endswith(__TOPIC_SCROLL_INTERVAL__ + "/set"):
+		  val = float(msg)
+		  if val > 0.0:
+			self.scroll_interval = val
+			print("changed scroll_interval to ", self.scroll_interval)
+            self.mqtt.publish(self.topic + "/" + __TOPIC_SCROLL_INTERVAL__, self.scroll_interval, 1 )
+		  else:
+			print("error not >0.0: ", val)
+			
+		  
+		  
+		  
+		if message.topic.endswith(__TOPIC_TEXT__ + "/set"):
+          self.text = msg
+		  print("changed text to ", self.text)
+          self.mqtt.publish(self.topic + "/" + __TOPIC_TEXT__, self.text, 1 )
+
+          
+
+    def on_connect(self, client, userdata, flags, rc):
+        print("Connected to MQTT Broker")
+        self.mqtt.subscribe(self.topic + "/#")
+        self.connected = True
+
+
+    def loop_forever(self):
+      run = True
+
+      while run:
+          self.mqtt.loop()
+
+		
+          self.display.print(self.text[poscount])
+          poscount += 1
+		  poscount %= len(self.text)
+          time.sleep(self.scroll_interval)
+			
+		  

src/main.py

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+#!/usr/bin/python3
+from controller import Controller
+from argparse import ArgumentParser
+
+parser = ArgumentParser(description="MQTT Control of RPI.")
+parser.add_argument(dest="host",type=str,help="Host name of the MQTT broker")
+parser.add_argument(dest="topic",type=str,help="set the base topic")
+
+
+
+
+if __name__ == "__main__":
+    args = parser.parse_args()
+    controller = Controller(args.topic,args.host)
+    controller.loop_forever()