umqtt.simple: Add example to toggle an LED on received subscribed message.

umqtt.simple/example_sub_led.py

@@ -0,0 +1,49 @@
+from umqtt.simple import MQTTClient
+from machine import Pin
+import ubinascii
+import machine
+import micropython
+
+
+# ESP8266 ESP-12 modules have blue, active-low LED on GPIO2, replace
+# with something else if needed.
+led = Pin(2, Pin.OUT, value=1)
+
+# Default MQTT server to connect to
+SERVER = "192.168.1.35"
+CLIENT_ID = ubinascii.hexlify(machine.unique_id())
+TOPIC = b"led"
+
+
+state = 0
+
+def sub_cb(topic, msg):
+    global state
+    print((topic, msg))
+    if msg == b"on":
+        led.value(0)
+        state = 1
+    elif msg == b"off":
+        led.value(1)
+        state = 0
+    elif msg == b"toggle":
+        # LED is inversed, so setting it to current state
+        # value will make it toggle
+        led.value(state)
+        state = 1 - state
+
+
+def main(server=SERVER):
+    c = MQTTClient(CLIENT_ID, server)
+    # Subscribed messages will be delivered to this callback
+    c.set_callback(sub_cb)
+    c.connect()
+    c.subscribe(TOPIC)
+    print("Connected to %s, subscribed to %s topic" % (server, TOPIC))
+
+    try:
+        while 1:
+            #micropython.mem_info()
+            c.wait_msg()
+    finally:
+        c.disconnect()