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Second Node

For this section, we assume that you have successfully set-up UlnoIoT on the Raspberry Pi and are able to access the websites on it as well as have set-up your first node and can control its onboard led via the node-RED web gui.

The goal of this tutorial is to show you how to adopt and initialize a second node and then connect them together over the air (OTA) via Node-RED.

Let's get started...

New Node

  • Navigate back to your IoT system example configuration folder

    As you have seen, each node has its own configuration folder in UlnoIoT.

  • For a second node, we need therefore another node-folder. We can quickly create one, based on a node-template.

    For that, make sure, you are still in the example system configuration folder and activate again the user menu.

    In the user menu, select Create New Node Folder, and after verifying the destination path (which should be iot-test/), select Yes, run create_node_template. Confirm a (hopefully) successful creation, and you wil be back in cloudcmd's web file panel.

    You should see there a new folder called new-node (next to the old folder node1, the README.rst and system.conf).

  • Select the new folder by mouse or keyboard, and press the rename button (or the F2 key) and rename the folder into node2.

  • Navigate into the node2 folder, you should see the files: README.rst, key.txt, node.conf, and setup.cpp

  • If you are not using a Wemos D1 Mini as new node, edit node.conf and enter the new board.

  • Make sure to open another ulnoiot documentation web-page for reference. And open from there the command reference.

  • In the file view, select setup.cpp and edit it (with edit button or F4 key).

    You should see a small explanation comment block. You should now completely remove it to have an empty configuration file.

  • In the command reference open the button help and copy from there the example configuration (including semicolon), something like this: input(lower, D2, "depressed", "pressed");

    Paste this into the setup.cpp editor.

  • Change it to input(b1, D3, "up", "down");

  • Leave the editor (press ok or by mouse the x in the upper right corner) and agree to save the file.

  • Like in the first node tutorial described, adopt now node2. (attach button, activate adoption mode, count Morse blinks, use phone to set own WiFi network credentials, finish calling adopt/initialize from user menu in node2 folder).

Visually Programming the Connections

  • After successful adoption, open the Node-RED page. Here you have to probably enter username (ulnoiot) and password (iotempire) again.

    You should see a Node-RED flow with five nodes.

  • Notable here are the two pink nodes at the sides, one labeled node1/b1 and one node1/blue/set

    These are so called mqtt (Message Queuing Telemetry Transport) nodes. They are our bridge to the IoT communication language.

  • The new node, we just configured, is sending data on the topic node2/b1

  • Therefore, create a new mqtt input node, by dragging it from the left into the current flow. Double click it and set its topic to node2/b1.

  • Also create a debug output node (drag it into the pane) and draw a wire from the mqtt-node port to the debug-port.

  • Press the red deploy button (in the upper right) corner.

  • Under the red deploy button is a little column with the symbol of a little bug, activate it and press the button connected to your new node several times.

    You should see several up and down messages in the debug log.

  • Add a change-node and configure it so that it replaces up with off and down with on.

  • Wire this change-node between the new mqtt input node for our node2 button controller and the mqtt output labeled node1/blue/set.

  • Deploy and press the button on node2, observer the onboard led on node1.

Congratulations!! You can remote control your led!

If you still have some time, try to use this new button to actually toggle the led. Study for this the rbe and toggle node. What is happening in them?

Top: ToC, Previous: First Node, Next: External Resources. Versão em português aqui.