Reduce MQTT update frequency

mqttclient/fanATserial2mqtt.py

@@ -7,23 +7,27 @@ import serial
 
 MAXIMUM_COMMUNICATION_FAILURE=100
 
+TEMPERATUR_MIN_DIFFERENCE   = 2
+TARGET_MIN_DIFFERENCE       = 1
+RPM_MIN_DIFFERENCE          = 50
+
 # MQTT Settings
 mqtt_server=os.environ['MQTT_SERVER']
 mqtt_topic=os.environ['MQTT_TOPIC']
 # SERIAL Port
 serial_device=os.environ['SERIAL_DEVICE']
 
+# Start mqtt
+client_id = f'python-fan-ctrl'
+client = mqtt_client.Client(mqtt_client.CallbackAPIVersion.VERSION2)
+# Start Serial communication
+ser = serial.Serial(serial_device, 115200, timeout=1)  # open serial port
 
 # The callback for when a PUBLISH message is received from the server.
 def on_message(client, userdata, msg):
     print(msg.topic+" "+str(msg.payload))
 
-
+# Handle MQTT Commands
-# Start mqtt
-client_id = f'python-fan-ctrl'
-client = mqtt_client.Client(mqtt_client.CallbackAPIVersion.VERSION2)
-
-
 def on_connect(mqttc, obj, flags, reason_code, properties):
     client.subscribe(mqtt_topic + "cmd/led")
     client.subscribe(mqtt_topic + "cmd/rpm")
@@ -42,15 +46,18 @@ if (not (mqtt_topic)):
 client.connect(mqtt_server, 1883)
 client.loop_start()
 
-# Start Serial communication
-ser = serial.Serial(serial_device, 115200, timeout=1)  # open serial port
 client.publish(mqtt_topic + "device", ser.name) # check which port was really used
 
 SerialCommunicationFailureCounter=0
 
+# store last published value
+lastTemperatur  = -1
+lastRPM         = -1
+lastTarget      = -1
+
 # Endless Loop
-while True:
+try:
-    try:
+    while True:
         try:
             if (not (ser.is_open)):
                 ser.open()
@@ -84,10 +91,16 @@ while True:
 
             if ((temperatur) and (percent) and (rpm)):
                 parseError=False
-                temperatur = temperatur.strip()
+                currentTemperatur = float(temperatur.strip())
-                client.publish(mqtt_topic + "temperatur", str(temperatur))
+                if (abs(currentTemperatur - lastTemperatur) > TEMPERATUR_MIN_DIFFERENCE):
+                    client.publish(mqtt_topic + "temperatur", str(currentTemperatur))
+                    lastTemperatur = currentTemperatur
+
                 if (percent.endswith('/100')):
-                    client.publish(mqtt_topic + "target", str(percent[:-4]))
+                    currentTarget = int(percent[:-4])
+                    if (abs(lastTarget - currentTarget) > TARGET_MIN_DIFFERENCE):
+                        client.publish(mqtt_topic + "target", str(currentTarget))
+                        lastTarget = currentTarget
                 else:
                     client.publish(mqtt_topic + "debug", "target%% invalid:" + str(percent))
                     parseError=True
@@ -95,7 +108,10 @@ while True:
                 # remove new line for last element
                 rpm = rpm.replace('\r','').replace('\n','')
                 if (rpm.endswith('RPM')):
-                    client.publish(mqtt_topic + "rpm", str(rpm[:-3]))
+                    currentRPM = int(rpm[:-3])
+                    if (abs(currentRPM-lastRPM) > RPM_MIN_DIFFERENCE):
+                        client.publish(mqtt_topic + "rpm", str(currentRPM))
+                        lastRPM = currentRPM
                 else:
                     client.publish(mqtt_topic + "debug", "RPM invalid:" + str(rpm))
                     parseError=True
@@ -108,9 +124,10 @@ while True:
         else:
             time.sleep(0.2)
 
-    except (KeyboardInterrupt, SystemExit):
+except (KeyboardInterrupt, SystemExit):
+    print("User aborted service ...")
     client.publish(mqtt_topic + "debug", "User aborted service")
     time.sleep(0.5)
-        print("User aborted service")
+    print("service Dead")
 
 client.loop_stop()