Blink

The blink program uses the LED (light-emitting diode) built into Maker Board to flash on and off. To do that, you need to tell Maker Board that the LED is an OUTPUT that should be turned on (HIGH) and off (LOW) with a pause between each command.

Code

The code below already works and is ready to upload! Build the circuit following the video and card above. Upload the code to your Maker Board. Then, tinker with the code, change numbers, or scroll down to the challenges to learn what each piece of the program does.

/* * Blink - makes a single LED blink on and off */ void setup() { pinMode(13, OUTPUT); // pin 13 - change value if you have LED on diff pin } void loop() { digitalWrite(13, HIGH); // set pin 13 to high voltage, turning LED on delay(1000); // wait 1000 milliseconds, or one second. digitalWrite(13, LOW); // set pin 13 to low voltage, or zero. LED off. delay(1000); //wait one second before starting the loop again. } // (c) 2018 Let's Start Coding. License: www.letsstartcoding.com/bsdlicense

Challenges

How many can you complete? Change the code and hardware according to the challenges below. Upload your code to see the effect when you're finished. Complete a challenge? Check it off the list!

Change delay(1000); to delay(100); in both places in your code.

Change:
- pinMode(13,OUTPUT); to pinMode(12,OUTPUT);.
- digitalWrite(13,HIGH); to digitalWrite(12,HIGH).
- digitalWrite(13,LOW); to digitalWrite(12,LOW);.
If your LED is not in port 12, move it there.

Make both delays such low numbers that you can barely see the LED flicker. What number is that for your delay?

Try to blink the LED once every 2 seconds. Use a timer to check yourself.

Replace your LED for a different single-color LED. Use the blue component cards to understand how to plug it in!

Delete the digitalWrite(13,LOW) command. What happens? Why?

Videos

This is a playlist of videos that help you understand how the example code above works. First in the playlist is a walkthrough of the code, step-by-step. Next are short videos covering the concepts used in this program.

Read the Code Walkthrough Text (click to open)

Concepts

These are the new code concepts covered in this example program. To become a great coder, read through these concepts to learn new vocabulary.

New Concept: Loops

Almost every program you write will use loops, or repeating statements. Computers don't get bored or distracted, so they can run the same code over and over with no trouble. Depending on what type of loop you use, you can have something repeat forever, a set number of times, or only while something else is causing the loop to occur (like a button press).

You'll see in later lessons what types of loops are available and how to use them together so that you can control the repetition of many different parts of the same program.

New Concept: Functions with Arguments

Functions are everywhere in programming. They're basically groups of code that run together. Some functions take in information, change it, and spit out something different. For example, imagine an equation (x+2). If you say x = 2, then the result will be 4. If you say x = 1, the result will be 3. That is a tiny function that takes in information and modifies it.

Some functions are built-in to the programming environment you use, so you won't see exactly how they work. That's a good thing, because it means a previous developer has hidden lots of complexity so you don't have to deal with it.

When you have to give information to a function for it to work, the information you give it is an argument. The required arguments for a function are designed by the person who coded the function, so you can't change what the arguments are without changing the function itself.

For example, pinMode() needs two arguments: pin number and OUTPUT, INPUT, or INPUT_PULLUP. Even if you want to set pins 10 and 11 as OUTPUTs, that's not allowed by the function- it can only use two arguments.

When you see a new function, it's good to learn what arguments it requires and what output, if any, it will have.

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