Holiday Light Show

Holiday Light Show is one of our standard Apps that comes with the Liberty IoT Hub.

We are using it as an example for developers to learn application development.

Liberty-IoT-OS and Liberty App Engine is the one and only logically complete IoT system.

A logically complete IoT system gives users complete control to use any possible algorithm over devices.

Nevertheless, algorithms (Apps) still have to be built by programmers. However, regular users can simply use the Apps in the most intuitive and straightforward way, without writing a single line of code.

Creating the App

In the “Develop” tab, click “Add” button on the upper left side tool-bar.

Develop Add App

A dialog pops up. Choose your Developer Name. In this example, the Application is named “Tutorial1”.

Create App

An Application with the name “Tutorial1” is created. Note in the example we use Developer Name of “LibreHome”. You need to use your own developer name.

App Name Created

On the right side a source code editor will open with title of “Tutorial1”.

Icons

The applications are displayed with icons indication the current status of the application.

  • Lua New Edit - Lua new application, checked out for editing
  • Lua Production Edit - Lua application, currently running in production mode, source code checked out for editing
  • Lua Disabled - Lua application, currently disabled by user
  • Lua Disable Edit - Lua application, currently disabled by user, source code checked out for editing
  • Lua Error - Lua application, currently disabled because of error
  • Lua Error Edit - Lua application, currently disabled because of error, source code checked out for editing

Copy Source Code

Copy the code below to the editor.

function MyLightShow(groups)
	while true do
		-- groups is a list of control group
		for _, group in ipairs(groups) do
      		for _, lightState in ipairs(group.lightStates) do
				Libre_DeviceLevelSet(lightState.light, lightState.onLevel)
			end
			Libre_Wait(group.wait * 1000)
    	end		
	end
end

Deployment

From tool bar on top, drop “Developer” menu, choose “Deploy”.

Deploy App

App Friendly Name

An editor dialog will pop up. Note the app file name is “Tutorial1”. Developer can give it a user friendly name. It can be any string. In this example, we give it a name “Libre Home Tutorial My Light Show”.

App Name Edit

Edit Input Data Structure (Signatures)

This step is very important! Since Lua is dynamic language, the function signatures can not be inferred from techniques such as reflection (in Java or .Net).

Developer has to manually specify the exact structure using our GUI tool.

The final signature for MyLightShow function looks like below:

  • The function only takes 1 argument, “groups”. It is an array (we call it “List”). We give it a name “Light Groups” (in “Display Name” column).
  • Based on the code, each item in the array is a struct (like “class” in C++ or Java, we call it “Table”). Naturally we give it a name “Light Group”.
  • According to code, each “Light Group” object has two members, “lightStates” and “wait”. Those members has to be added with exactly the same names appeared in the code (in “Native Name” column). The “Display Name” can be any string developer chooses. In this case, we name them “List of Lights” and “Wait for (Seconds)”.
  • Member “lightStates” is another array.
    • “lightStates” (List of Lights) is an array of struct (Table)
    • We give “lightStates” member a friendly name of “Light & Level”.
    • “Light & Level” has two members
      • Member “light” is a device, we will take both “On/Off” devices and “Level Control” devices.
      • Member “onLevel” is an integer with value between 0 and 255, inclusive.
      • Friendly name of “Light” and “Level” are given.
  • Member “wait” is a number, representing wait seconds. A real number with ‘0.001’ (millisecond) precision.

App Signature

Attributes

Apart from the friendly name “Display Name”, extra constraints of some data types can be given.

Device Types

Remember we only want to take “On/Off” and “Level Control” devices.

We need to add to types of devices separately.

App Arg Device Type

App Arg Device Type

Finally “Device Type” will have two entries.

App Arg Device Type

Other Attributes

Using the “Attribute” menu on the top tool bar, extra attributes can be added to data type node.

Apart from “Device Type”, we added two other attributes to “Light”.

App Arg Light

“Min”, “Max” and “Step” specified for “Level”.

App Arg Level

“Min”, “Max” and “Step” specified for “Wait for (Seconds)”. App Arg Wait

For more information about Attributes, please read the chapter “Attributes”.

Testing the App

From your Smartphone, navigate to “Tasks” -» “Add”.

You will be able to see newly added App “Libre Home Tutorial My Light Show”. (You can also search for it).

Choose the only function “My Light Show”.

Create Task

Create a New Task

Follow the instruction in “Creating a Task”.

Add two lights to the task. Once the task is started, the two lights will start blinking with the pattern you specified.

Create Task