Using the LED Matrix
The LED Matrix is a 16 x 32 LED display that stands in front of TimeSquAir.
This tutorial show how to use the provided nodes to use that display.
The LED Matrix “subflow”
A Subflow is a node made with a flow. There is two ways to make a node: one way is to use the javascript programming language, the second way is to use a flow.
To easily address the most frequent use, there is a orange node that does the job:
You can use this node to display simple texts.
To do more, as mixing text and pictures, use the nodes below.
The LED Matrix nodes
You can find the LED Matrix nodes in the palette:
First use a LED Blank node to start. Then use a mix of LED Text and LED Picture nodes to compose the message. End with a LED Matrix node and use a Go node to activate the whole.
Display a simple text
To display a simple text, a LED Text node is enough:
Double click the LED text node to edit the text to be shown.
See later if the text to display should be calculated.
Display a picture
Add the picture file on the Pi
In order to add a picture on the LED matrix, you have to add the picture on the Pi.
Just get the destination folder using Samba: in your PC file browser, open:
\\myTimeSquAir\TheThingBox\root\userdir
where “myTimeSquAir” should be replaced by the name of your TimeSquAir.
You can do it by opening a file explorer window and changing its adress by this one in the address bar. In the picture below, I access my TimSquAir which name is “ttbbeacon”:
In you userdir, find or create a folder named pictures and put your pictures in it. You can use png, jpg or ppm images.
Modify the flow
Add a LEDPicture node and fill it with the path of the picture:
and insert it in the flow.
Below is an example of mixed text and pictures:
Using calculated values
Of course, some value may not be known at this time, thus should be calculated at runtime.
The solution is to use a function node and calculate the value in javascript (an easy to use software language).
A basic example
Here is the flow with a new function node that sets the message to “500”:
Double click on the function node to add the javascript:
- line1: the message property of the msg object that goes from the beginning to the end of the flow is set to “500”. We do that because we know (its written in the info tab) that the LEDText node uses that property to find the text to display. You can do any calculation using javascript to calculate the accurate message.
- line2: we return the modified msg object to let it follow the rest of the flow.
Get a value from the cloud
Make it more useful and go fetch the bitcoin value on the web.
We get the value by making an HTTP request to https://paymium.com/api/v1/data/eur/ticker which returns data like:
To do that, we use an HTTP Request node and fill it with the address above:
Then we link a function node to feed the msg.message as above:
Here is the final flow:
Change display settings
By editing the LEDMatrix node, you can change the speed and the intensity of the display.