---+ Exercises for session 3: MQTT and Cayenne ---++ Exercise 1: Install mosquitto on your machine. On Ubuntu Linux this can very easily be accomplished with apt. On Windows it is almost as easy. For details see http://www.steves-internet-guide.com/install-mosquitto-broker/ Try the _mosquitto_ communication: * <p>Start the mosquitto broker</p> * <p>Start mosquitto_sub subscribing to the “AFNOG19” topic</p> * <p>Start mosquitto_pub publishing some message to the topic “AFNOG19”</p> * <p>observe the message being seen in mosquitto_sub</p> ---++ Exercise 2: Write you own MQTT client in Python publishing a message to “AFNOG19” every 2 s. Have a look at the [[https://github.com/micropython/micropython-lib/tree/master/umqtt.simple][umqtt.simple class]] to see how to accomplish this. Write the program and start it with thonny. You must know the IP address of the machine on which your mosquitto broker is running. Use _ifconfig_ to find out. Subscribe to the “AFNOG19” topic with mosquitto_sub and observer that the messages are arriving. Write an MQTT client that subscribes to the “AFNOG19” topic and that prints messages coming in. Write a program controlling a LED as we did during the lectures. ---++ Exercise 3: Register a user on https://mydevices.com/cayenne/signup. Watch the introductory film and have a look at the documentation pages. Add a device by clicking on “Bring Your Own Thing”. Have a look at your Cayenne credentials. ---++ Exercise 4: Write a program connecting to Cayenne. Observe that the dashboard is coming up. ---++ Exercise 5: Write a program that sends a dummy voltage value to Cayenne on channel 0. The voltage values should range from 0 to 3300 mV (the voltages on the ESP8266). Wait for 2 s minimum between each value. Observe the widget coming up on the dashboard. Fix the widget on the dashboard and change the widget parameters (e.g. the name). ---++ Exercise 6: Add a gauge widget with ranges 0 .. 1V, 1V .. 2V, 2V .. 3.3V. Run your program sending the dummy voltages and observe how the dashboard displays them. ---++ Exercise 7: Add a dummy measurement on atmospheric pressure to your program. The normal air pressure is around 950 hPa (hecto Pascal). ---++ Exercises 8: Create a slider and a push button on your dashboard. -- %USERSIG{UliRaich - 2019-05-15}% ---++ Comments %COMMENT%
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Topic revision: r1 - 2019-05-15 - UliRaich
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