In last post, we have setup development environment for coding and uploading scratches to NodeMCU, an IoT device.
This post, we will upload and run two examples to demonstrate how IoT device sending data into Cloud and receiving commands from Cloud. You can find the source code and MQTT library requirement on github.
4. Architecture Diagram
It involves several tiers and components to make the whole IoT loop. However, you will just focus on device communication with MQTT, all other components have been setup properly.
5. Wiring Diagram
For the two testing examples, you can just use the following diagram:
And here is an example of actual wiring used to test the example code:
6. Test Sample #1
Demonstrate that IoT device interacts with Internet over MQTT. You can get the source code from github: https://github.com/raymondxie/iotws/blob/master/iotws_mqtt.ino
Please note, you need modify the code by supplying necessary connection parameters for WiFi network and MQTT broker. Check the parameter values with your instructor.
The example let you press a button, the event is sent to MQTT broker in the Cloud, and NodeMCU board is also listening to that channel for input, essentially the information just come right back to the board. Based on the button press count (even / odd count), the board plays a different tune for you.
Have fun playing the tunes!
7. Test Sample #2
Send a message into Oracle IoT Cloud Service (IoTCS) by press of a button. You can get the source code from github: https://github.com/raymondxie/iotws/blob/master/iotws_iotcs.ino
Please note, you need modify the code by supplying necessary connection parameters for WiFi network and MQTT broker. Check the parameter values with your instructor.
This sample let you press a button, and a message along with your name is sent to MQTT broker. There is a Raspberry Pi listening to inputs to that particular MQTT channel. The Raspberry Pi acts as a gateway to IoTCS, and relays the message to it. You can then verify your message with your name in the IoTCS console.