added example for controlling a chamber (untested)

examples/chamber.py

+
+
+#!/usr/bin/env python3
+
+import paho.mqtt.client as paho
+import paho.mqtt.publish as publish
+import time
+import socket
+import struct
+from threading import Event
+
+CHAMBER_NAME = "lctc-c0X"
+TARGET_TEMPERATURE = 10.0
+DELTA = 0.5
+TIMEOUT = 60.0
+CHAMBER_TEMPERATURE_TOPIC = "sht21/"+CHAMBER_NAME+"/temp"
+temperature_reached = Event()
+
+client = paho.Client(client_id="chamber_controller_" + socket.gethostname(), clean_session=True)
+
+def on_message(client, userdata, msg):
+    if msg.topic == CHAMBER_TEMPERATURE_TOPIC:
+        temp, = struct.unpack("d", msg.payload)
+        if abs( temp - TARGET_TEMPERATURE ) < DELTA:
+            temperature_reached.set()
+    else:
+        print( "[on_message] {} {}".format(msg.payload, msg.topic) )
+
+def on_disconnect(client, userdata, rc):
+    print(" [on_disconnect] {}".format( rc ))
+
+def on_connect(client, userdata, flags, rc):
+    client.subscribe(CHAMBER_TEMPERATURE_TOPIC, qos=2)
+
+def set_temp(temp):
+    client.publish("chamber/"+CHAMBER_NAME+"/temp", struct.pack("d", temp), qos=2)
+
+if __name__ == "__main__":
+    client.connect( "localhost", port=1883, keepalive=5 )
+    client.on_connect = on_connect
+    client.on_message = on_message
+    client.on_disconnect = on_disconnect
+    client.loop_start()
+
+    while True:
+        # Wait until temperature has been reached
+        if temperature_reached.wait(TIMEOUT):
+            print("timeout reached.")
+        # Do something here for 1 minute
+        time.sleep(60.0)
+        # Increase target temperature
+        TARGET_TEMPERATURE += 1.0
+        set_temp( TARGET_TEMPERATURE )
+        temperature_reached.clear()
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