Program the LEDs

Step 1

Creating variables

Each LED is connected to a pin on the Smart Inventor Board, so the first thing you need to do is give each of your pins a variable name. These are going to go at the top of your code, so place your mouse cursor at void setup() and hit the enter key to give yourself room to do this. Then enter the code below.

int name = pin_number;
int LEDPIN11 = 11;

Step 2

Creating more variables

Just in case, keep line 1 as a comment so you remember how to create this particular variable.

Create variables for pins 11 through 18. Unless you can type super fast, copy and paste is your friend! Your code should look like the one below.

int LEDPIN11 = 11;
int LEDPIN12 = 12;
int LEDPIN13 = 13;
int LEDPIN14 = 14;
int LEDPIN15 = 15;
int LEDPIN16 = 16;
int LEDPIN17 = 17;
int LEDPIN18 = 18;

Step 3

Learning pinMode() function

pinMode( ) usually looks like the example below.

pinMode(name of declared pin, pin assigned as either INPUT or OUTPUT);

When a pin is declared as an input, this means that the pin takes in or reads information. Other parts of your robot, like sensors, can also be declared as an input.

When a pin is declared as an output, this means that the pin performs an action, like flashing a light or making a noise.

Step 4

Use pinMode() function

Are you ready to use pinMode()? Use it to assign LEDPIN11 through LEDPIN18 as outputs.

pinMode(LEDPIN11,OUTPUT);
pinMode(LEDPIN12,OUTPUT);
pinMode(LEDPIN13,OUTPUT);
pinMode(LEDPIN14,OUTPUT);
pinMode(LEDPIN15,OUTPUT);
pinMode(LEDPIN16,OUTPUT);
pinMode(LEDPIN17,OUTPUT);
pinMode(LEDPIN18,OUTPUT);

Step 5

digitalWrite() function

digitalWrite( ) usually looks like the example below.

digitalWrite(name of declared pin, pin state either HIGH or LOW);

When an LED’s state is high, the LED will turn on. When the LED’s state is low, the LED will turn off.

You can assign pin states to your LEDs in void loop() since they will be running continuously. Your code should look like the one below.

digitalWrite(LEDPIN11, HIGH);
digitalWrite(LEDPIN12, HIGH);
digitalWrite(LEDPIN13, HIGH);
digitalWrite(LEDPIN14, HIGH);
digitalWrite(LEDPIN15, HIGH);
digitalWrite(LEDPIN16, HIGH);
digitalWrite(LEDPIN17, HIGH);
digitalWrite(LEDPIN18, HIGH);

digitalWrite(LEDPIN11, LOW);
digitalWrite(LEDPIN12, LOW);
digitalWrite(LEDPIN13, LOW);
digitalWrite(LEDPIN14, LOW);
digitalWrite(LEDPIN15, LOW);
digitalWrite(LEDPIN16, LOW);
digitalWrite(LEDPIN17, LOW);
digitalWrite(LEDPIN18, LOW);

Step 6

delay() function

Quick review! delay( ) usually looks like the code below.

delay( time in milliseconds );

delay() is a function that will define how long an action should be performed. There are 1000 milliseconds in 1 second, so if your action should run for 3 seconds, your delay() time should be 3000.

You can add one second delays to the end of each digital write block.

Step 7

Final code

Your final code should look something like this:

//declares global variables used in the code
int LEDPIN11 = 11;
int LEDPIN12 = 12;
int LEDPIN13 = 13;
int LEDPIN14 = 14;
int LEDPIN15 = 15;
int LEDPIN16 = 16;
int LEDPIN17 = 17;
int LEDPIN18 = 18;

void setup() {
//pin assignments
pinMode(LEDPIN11, OUTPUT);
pinMode(LEDPIN12, OUTPUT);
pinMode(LEDPIN13, OUTPUT);
pinMode(LEDPIN14, OUTPUT);
pinMode(LEDPIN15, OUTPUT);
pinMode(LEDPIN16, OUTPUT);
pinMode(LEDPIN17, OUTPUT);
pinMode(LEDPIN18, OUTPUT);
}

void loop() {
//sets the LED state to HIGH
digitalWrite(LEDPIN11, HIGH);
digitalWrite(LEDPIN12, HIGH);
digitalWrite(LEDPIN13, HIGH);
digitalWrite(LEDPIN14, HIGH);
digitalWrite(LEDPIN15, HIGH);
digitalWrite(LEDPIN16, HIGH);
digitalWrite(LEDPIN17, HIGH);
digitalWrite(LEDPIN18, HIGH);
delay(1000);

//sets the LED state to LOW
digitalWrite(LEDPIN11, LOW);
digitalWrite(LEDPIN12, LOW);
digitalWrite(LEDPIN13, LOW);
digitalWrite(LEDPIN14, LOW);
digitalWrite(LEDPIN15, LOW);
digitalWrite(LEDPIN16, LOW);
digitalWrite(LEDPIN17, LOW);
digitalWrite(LEDPIN18, LOW);
delay(1000);
}

TIP: press ctrl + t to auto format your code.

Try changing up your code so you can make an LED light show!

Step 8

Video

Still not sure about the LED program, or just want to make sure you did it right? Watch the video!

This lesson works with:

Grade level:

Approx. time required:

CSTA

CCSS