(r6) MQTTAndCayenne < AFNOG

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%SLIDESHOWSTART%
---+ Setting up an !IoT
<h1 align="center">Session 3: MQTT and Cayenne</h1> <h1 align="center">Uli Raich<br /><br />Formally CERN, Geneva, Switzerland</h1>

---++ 
---+ The Network Layers

The !WeMos D1 mini has a built-in !WiFi interface<br /><br />In order to communicate with other !IoT nodes we must therefore

connect to the !WiFi network first<br /><br />On top of !WiFi we will run a TCP session<br /><br />On top of TCP we will run the MQTT protocol<br /><br />On top of MQTT we have dedicated topics and payloads imposed by Cayenne

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---+ Accessing the !WiFi network

<img alt="wifiDemoCode.png" height="349" src="%ATTACHURL%/wifiDemoCode.png" title="wifiDemoCode.png" width="547" />
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---+ Accessing the !WiFi network from Micropython

<img alt="wifiConnect.png" height="803" src="%ATTACHURL%/wifiConnect.png" title="wifiConnect.png" width="1056" />

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---+ MQTT

MQTT (Message Queuing Telemetry Transport: a publish-subscribe based <br /><br />message protocol running of top of TCP.<br /><br />A processor can subscribe to messages of a certain “topic” and/or it can push its<br /><br />results on a certain topic

<img alt="mqttPostOfffice.png" height="267" src="%ATTACHURL%/mqttPostOfffice.png" title="mqttPostOfffice.png" width="722" />

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---+ MQTT Demo

<img alt="mqttDemo.png" src="%ATTACHURL%/mqttDemo.png" title="mqttDemo.png" />

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---+ The Micropython library

<img alt="micropython-lib.png" height="464" src="%ATTACHURL%/micropython-lib.png" title="micropython-lib.png" width="654" />

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---+ A MQTT example using umqtt.simple

<img alt="umqttDemo.png" height="564" src="%ATTACHURL%/umqttDemo.png" title="umqttDemo.png" width="535" />

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---+ Sending dummy temperature data

<img alt="mqttDummySensorDemo.png" height="582" src="%ATTACHURL%/mqttDummySensorDemo.png" title="mqttDummySensorDemo.png" width="535" />

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---+ Receiving commands

Receiving commands is a bit more tricky! We must:<br /><br />
   * Write a callback function and register it with the MQTT client
   * This function takes 2 arguments:
   * The topic
   * The payload
   * Subscribe to the topic
   * Wait forever. The callback function will be executed when a message with the <br />topic we subscribed to, will arrive
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---+ Subscribe a callback

<img alt="subscribeDemo.png" height="650" src="%ATTACHURL%/subscribeDemo.png" title="subscribeDemo.png" width="539" />

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---+ Callback result

%SLIDESHOWEND%

-- %USERSIG{UliRaich - 2019-05-14}%

---++ Comments

%COMMENT%

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
odp	afnog19-ws-session3.odp	r1	manage	5245.0 K	2019-05-15 - 19:13	UliRaich
png	micropython-lib.png	r1	manage	75.2 K	2019-05-14 - 17:31	UliRaich
png	mqttDemo.png	r1	manage	191.3 K	2019-05-14 - 17:23	UliRaich
png	mqttDummySensorDemo.png	r1	manage	74.4 K	2019-05-20 - 18:40	UliRaich
png	mqttExample.png	r2 r1	manage	73.2 K	2019-05-15 - 16:12	UliRaich
png	mqttPostOfffice.png	r1	manage	50.2 K	2019-05-14 - 17:18	UliRaich
png	realData.png	r1	manage	27.7 K	2019-05-15 - 17:12	UliRaich
png	subscribeDemo.png	r1	manage	78.3 K	2019-05-20 - 18:45	UliRaich
png	umqttDemo.png	r2 r1	manage	72.2 K	2019-05-14 - 17:38	UliRaich
png	wifiConnect.png	r1	manage	128.4 K	2019-05-14 - 17:18	UliRaich
png	wifiDemoCode.png	r1	manage	43.8 K	2019-05-15 - 16:14	UliRaich

Topic revision: r6 - 2019-05-21 - UliRaich