Add Example for Cellular Interfaces

docs/conf.py

@@ -136,7 +136,7 @@
         "AdafruitAdafruit_IO Library Documentation",
         author,
         "manual",
-    ),
+    )
 ]
 
 # -- Options for manual page output ---------------------------------------
@@ -167,5 +167,5 @@
         "AdafruitAdafruit_IOLibrary",
         "One line description of project.",
         "Miscellaneous",
-    ),
+    )
 ]

examples/adafruit_io_mqtt/adafruit_io_simpletest_cellular.py

@@ -0,0 +1,118 @@
+# Example of using the Adafruit IO CircuitPython MQTT client
+# to subscribe to an Adafruit IO feed and publish random data
+# to be received by the feed.
+#
+# Example by Tony DiCola for Adafruit Industries
+# Modified by Brent Rubell for Adafruit Industries, 2019
+import time
+from random import randint
+
+import board
+import busio
+import digitalio
+
+from adafruit_fona.adafruit_fona import FONA
+from adafruit_fona.adafruit_fona_gsm import GSM
+import adafruit_fona.adafruit_fona_socket as cellular_socket
+
+from adafruit_io.adafruit_io import IO_MQTT
+import adafruit_minimqtt as MQTT
+
+# Get MQTT details and more from a secrets.py file
+try:
+    from secrets import secrets
+except ImportError:
+    print("MQTT secrets are kept in secrets.py, please add them there!")
+    raise
+
+# Create a serial connection for the FONA connection
+uart = busio.UART(board.TX, board.RX)
+rst = digitalio.DigitalInOut(board.D4)
+
+# Initialize FONA module (this may take a few seconds)
+fona = FONA(uart, rst)
+
+# initialize gsm
+gsm = GSM(fona, (secrets["apn"], secrets["apn_username"], secrets["apn_password"]))
+
+while not gsm.is_attached:
+    print("Attaching to network...")
+    time.sleep(0.5)
+
+while not gsm.is_connected:
+    print("Connecting to network...")
+    gsm.connect()
+    time.sleep(5)
+
+# Define callback functions which will be called when certain events happen.
+# pylint: disable=unused-argument
+def connected(client):
+    # Connected function will be called when the client is connected to Adafruit IO.
+    # This is a good place to subscribe to feed changes.  The client parameter
+    # passed to this function is the Adafruit IO MQTT client so you can make
+    # calls against it easily.
+    print("Connected to Adafruit IO!  Listening for DemoFeed changes...")
+    # Subscribe to changes on a feed named DemoFeed.
+    client.subscribe("DemoFeed")
+
+
+def subscribe(client, userdata, topic, granted_qos):
+    # This method is called when the client subscribes to a new feed.
+    print("Subscribed to {0} with QOS level {1}".format(topic, granted_qos))
+
+
+def unsubscribe(client, userdata, topic, pid):
+    # This method is called when the client unsubscribes from a feed.
+    print("Unsubscribed from {0} with PID {1}".format(topic, pid))
+
+
+# pylint: disable=unused-argument
+def disconnected(client):
+    # Disconnected function will be called when the client disconnects.
+    print("Disconnected from Adafruit IO!")
+
+
+# pylint: disable=unused-argument
+def message(client, feed_id, payload):
+    # Message function will be called when a subscribed feed has a new value.
+    # The feed_id parameter identifies the feed, and the payload parameter has
+    # the new value.
+    print("Feed {0} received new value: {1}".format(feed_id, payload))
+
+
+# Initialize MQTT interface with the ethernet interface
+MQTT.set_socket(cellular_socket, fona)
+
+# Initialize a new MQTT Client object
+mqtt_client = MQTT.MQTT(
+    broker="http://io.adafruit.com",
+    username=secrets["aio_user"],
+    password=secrets["aio_key"],
+)
+
+# Initialize an Adafruit IO MQTT Client
+io = IO_MQTT(mqtt_client)
+
+# Connect the callback methods defined above to Adafruit IO
+io.on_connect = connected
+io.on_disconnect = disconnected
+io.on_subscribe = subscribe
+io.on_unsubscribe = unsubscribe
+io.on_message = message
+
+# Connect to Adafruit IO
+print("Connecting to Adafruit IO...")
+io.connect()
+
+# Below is an example of manually publishing a new  value to Adafruit IO.
+last = 0
+print("Publishing a new message every 10 seconds...")
+while True:
+    # Explicitly pump the message loop.
+    io.loop()
+    # Send a new message every 10 seconds.
+    if (time.monotonic() - last) >= 5:
+        value = randint(0, 100)
+        print("Publishing {0} to DemoFeed.".format(value))
+        io.publish("DemoFeed", value)
+        last = time.monotonic()