• One Edison connected to Wyliodrin;
• One LED;
• One 200 Ohm resistor;
• Two male-male jumper wires.

Connect the LED to the Edison following the schematics in the figure.

You will see, when you look at the LED, that it has two legs. One is longer, that one is usually the anode. The latter has to be plugged into the GPIO pin of the Edison. The shorter leg should to be connected to the resistor and then to the ground pin of the board. To understand the anode and the cathode of the LED, imagine these two following situations:

1. The cathode is connected ,through the resistor of course, to the ground. This means that the anode will be wired to the GPIO pin, which has to be High in order to make the LED light up.
2. The anode is connected to the VCC pin of the board. Which means that, should you want to light up the LED, the cathode has to be connected to the GPIO setted to Low . Don't forget this kind of a circuit also requires a resistor.

To sum it up, although the position of the resistor is not fixed, it can can either connect the ground to the cathode or the anode to the GPIO pin, the cathode should be connected to the ground to obtain the usually desired behaviour. Meaning you want the LED to light when the GPIO is set to HIGH and not to light when the GPIO is set to LOW. If you put the legs the other way around, the effect will be the opposite.

Streams is an inbuilt programming language used in Wyliodrin to create many complex IOT projects.

It is quite different from usual programming languages, and it can sometimes contain visual blocks as functions.

This programming language works not as an imperative one, but is based on data flow. The nodes will send messages to one another. You can look at these messages as JSON objects. Any message has two important fields: one will be the payload and a second one the topic. Any action in Streams starts with the run node. As you can see in its description, this node will set a payload at a certain interval. More specifically, you can choose in its settings to send the message at a certain time interval or at a specific time.

You go to the Wyliodrin Applications page and create a new application. You name it and select the Streams programming language, then, the example Led Blink - Streams. This will create an application that makes an LED connected to the pin 2 of the Edison blink.

Once created, you click on the new application's name to open it. A new window will open to display it. In this example, the run node will send a message every 1 second to the node that says blink. Look in its settings. The payload field will be a number, incremented by one. The blink node is the one which holds the visual blocks. Double click on the latter to see the function inside. It will be in Visual Programming. What it does is to set a variable new message with the value of the data sent from this node to the next one to come. Now, the very message is composed like this: take the payload sent from the first node and divide it by 2. Which means the new message will be either 1 or 0. The function returns just one of these values, depending on the case. The last node is simply the digital write function. It will ask as a parameter the pin number, so double click on it and specify the pin you are going to use. On this pin, it will write the message that was previously composed.

We said that usually the longer leg is the anode and the shorted one is the cathode. However, this is not standard, to make sure which is which, you should know that the cathode leg is always connected to the bigger part inside the LED.

You can easily add a button to turn on and off the LED.

• One Edison connected to \Wyliodrin;
• Two 200 Ohm resistor;
• Six male-male jumper wires;
• One button;
• One LED.

To connect it, just think about the button as a voltage divider, the same as for the thermistor. Look in the introduction to electronics to properly understand the concept.

You won't need to use more than 3 blocks.

• one is the usual run
• read the digital pin to which the button is connected
• write its value on the pin where the LED is wired

1. Connect two LEDs and one button that will light them up one by one.
2. Use one LED to write SOS using the international morse code.