Program the Trailer Bot

Step 1

What it does

The Trailer Bot can be controlled using a remote control. It can move forward or backward, curve to the right or left, and speed up or down.

This is the Trailer Bot’s pseudocode with the remote control:

If up is pressed, move forward.
Else, if down is pressed, move backward.
Else, if right is pressed, curve right.
Else, if left is pressed, curve right.
If F1 is pressed, speed up.
Else, if F2 is pressed, slow down.
Otherwise, stop.

Fun thing about the Trailer Bot: you can use the LEDs to tell how fast (or slow) it’s going! If you turn on the four middle LEDs (13, 14, 15, and 16), an increase or decrease in the number of LEDs that are on shows an increase or decrease in the Trailer Bot’s speed.

Step 2

Setup

There is a lot to include in the setup code! This is the breakdown:

Before void setup():

The Smart Inventor Library
The speed variable
The LED variables

In void setup():

The motors
The remote control
The LEDs’ output and state

#include <SmartInventor.h>

int speed = 60;

int speedMeterL = 13;
int speedMeterR = 16;
void setup() { 
    SmartInventor.DCMotorUse();
    SmartInventor.TVRemoconUse();

     pinMode(11, OUTPUT); // set up the LEDs
     pinMode(12, OUTPUT);
     pinMode(13, OUTPUT);
     pinMode(14, OUTPUT);
     pinMode(15, OUTPUT);
     pinMode(16, OUTPUT);
     pinMode(17, OUTPUT);
     pinMode(18, OUTPUT);

     digitalWrite(13, HIGH);
     digitalWrite(14, HIGH);
     digitalWrite(15, HIGH);
     digitalWrite(16, HIGH);
}

Step 3

Add remote control data

Create a variable to read the remote control and store information about the last button that was pressed. You want this information to be read continuously, so make sure it’s in void loop().

void loop() {
    int keyData = SmartInventor.TVRemoconData();
}

Step 4

Add buttons

Next up is the exciting part of the code: telling your motors how to move! You need to bust out your if, else if, and else statements to program how your Trailer Bot will move if certain buttons on the remote control have been pressed. Again, because this should be continuously checked, this part of the code should be in the void loop() section.

void loop() {

 int keyData = SmartInventor.TVRemoconData();

  if(keyData == KEY_U)
 {
 SmartInventor.DCMotor(M1, CCW, speed); // Move forwards
 SmartInventor.DCMotor(M2, CW, speed);
 }
 else if(keyData == KEY_D)
 {
 SmartInventor.DCMotor(M1, CW, speed); // Move backwards
 SmartInventor.DCMotor(M2, CCW, speed);
 }
 else if(keyData == KEY_L)
 {
 SmartInventor.DCMotor(M1, CW, speed); // Turn left
 SmartInventor.DCMotor(M2, CW, speed);
 }
 else if(keyData == KEY_R)
 {
 SmartInventor.DCMotor(M1, CCW, speed); // Turn right
 SmartInventor.DCMotor(M2, CCW, speed);
 }
 else
 {
 SmartInventor.DCMotor(M1, LOOSE, 0); // Stop
 SmartInventor.DCMotor(M2, LOOSE, 0);
 }

}

Step 5

Add F1 and F2

We’ve been telling you that your Trailer Bot can speed up or slow down, but you haven’t had the chance to program that part…until now! You can use the F1 and F2 buttons on the remote control to speed up or slow down the motors. Just like the buttons for directions, you need to use if and else if statements to do this.

You also need to have your program check your Trailer Bot’s speed before it can go faster or slower. Make sure to include a short delay so you have time to let go of the button before the speed changes.

void loop() {

 int keyData = SmartInventor.TVRemoconData();

 if(keyData == KEY_U)
 {
 SmartInventor.DCMotor(M1, CCW, speed); // Move forwards
 SmartInventor.DCMotor(M2, CW, speed);
 }
 else if(keyData == KEY_D)
 {
 SmartInventor.DCMotor(M1, CW, speed); // Move backwards
 SmartInventor.DCMotor(M2, CCW, speed);
 }
 else if(keyData == KEY_L)
 {
 SmartInventor.DCMotor(M1, CCW, speed); // Turn left
 SmartInventor.DCMotor(M2, CCW, speed);
 }
 else if(keyData == KEY_R)
 {
 SmartInventor.DCMotor(M1, CW, speed); // Turn right
 SmartInventor.DCMotor(M2, CW, speed);
 }
 else
 {
 SmartInventor.DCMotor(M1, LOOSE, 0); // Stop
 SmartInventor.DCMotor(M2, LOOSE, 0);
 }
 
 if(keyData == KEY_F1)
 {
     if(speed < 90) // make sure you are not going too fast
         {
             speed = speed + 20; // speed up
             delay(150);
         }
 }
 else if(keyData == KEY_F2)
 {
     if(speed > 30) // make sure you are not going too slow
         {
             speed = speed - 20; // slow down
             delay(150);
         }
 }

}

Step 6

Add LEDs

About those LEDs: they can display how high or low the current speed is. Each time the speed is increased or decreased, two more LEDs should be turned on or off.

void loop() { 
    int keyData = SmartInventor.TVRemoconData(); 

    if(keyData == KEY_U) { 
        SmartInventor.DCMotor(M1, CCW, speed); // Move forwards 
        SmartInventor.DCMotor(M2, CW, speed); 
    } 

    else if(keyData == KEY_D) { 
        SmartInventor.DCMotor(M1, CW, speed); // Move backwards 
        SmartInventor.DCMotor(M2, CCW, speed); 
    } 

    else if(keyData == KEY_L) { 
        SmartInventor.DCMotor(M1, CW, speed); // Turn left 
        SmartInventor.DCMotor(M2, CW, speed); 
    } 

    else if(keyData == KEY_R) { 
        SmartInventor.DCMotor(M1, CCW, speed); // Turn right 
        SmartInventor.DCMotor(M2, CCW, speed); 
    } 
    
    else { SmartInventor.DCMotor(M1, LOOSE, 0); // Stop 
        SmartInventor.DCMotor(M2, LOOSE, 0); 
    }  

    if(keyData == KEY_F1) {     
        if(speed < 90) // make sure you are not going too fast         
        {             
            speed = speed + 20; // speed up

            speedMeterL = speedMeterL - 1; //light up two more LEDs
            speedMeterR = speedMeterR + 1;

            digitalWrite(speedMeterL, HIGH);
            digitalWrite(speedMeterR, HIGH);
             
            delay(150);         
        } 
       }
     else if(keyData == KEY_F2) {     
        if(speed > 30) // make sure you are not going too slow         
        {             
            speed = speed - 20; // slow down

            speedMeterL = speedMeterL + 1; //turn off two outer LEDs
            speedMeterR = speedMeterR - 1;

            digitalWrite(speedMeterL, LOW);
            digitalWrite(speedMeterR, LOW);
 
            delay(150);         
        }
       }
    }

Step 7

Final code

This is what your final code should look like:

#include <SmartInventor.h>

int speed = 60;

int speedMeterL = 13;
int speedMeterR = 16;


void setup() {     
    SmartInventor.DCMotorUse();    
    SmartInventor.TVRemoconUse();     

    pinMode(11, OUTPUT); // set up the LEDs     
    pinMode(12, OUTPUT);     
    pinMode(13, OUTPUT);     
    pinMode(14, OUTPUT);     
    pinMode(15, OUTPUT);     
    pinMode(16, OUTPUT);     
    pinMode(17, OUTPUT);     
    pinMode(18, OUTPUT);     

    digitalWrite(13, HIGH);     
    digitalWrite(14, HIGH);     
    digitalWrite(15, HIGH);     
    digitalWrite(16, HIGH);}

void loop() {     
    int keyData = SmartInventor.TVRemoconData();     

    if(keyData == KEY_U) 
    {         
        SmartInventor.DCMotor(M1, CCW, speed); // Move forwards         
        SmartInventor.DCMotor(M2, CW, speed);     
    }     
    else if(keyData == KEY_D) 
    {         
        SmartInventor.DCMotor(M1, CW, speed); // Move backwards         
        SmartInventor.DCMotor(M2, CCW, speed);     
    }     
    else if(keyData == KEY_L) 
    {         
        SmartInventor.DCMotor(M1, CW, speed); // Turn left         
        SmartInventor.DCMotor(M2, CW, speed);     
    }     
    else if(keyData == KEY_R) 
    {         
        SmartInventor.DCMotor(M1, CCW, speed); // Turn right         
        SmartInventor.DCMotor(M2, CCW, speed);     
    }         
    else 
    { 
        SmartInventor.DCMotor(M1, LOOSE, 0); // Stop         
        SmartInventor.DCMotor(M2, LOOSE, 0);     
    }      

    if(keyData == KEY_F1) 
    {             
        if(speed < 90) // make sure you are not going too fast                 
        {                         
            speed = speed + 20; // speed up            

            speedMeterL = speedMeterL - 1; //light up two more LEDs            
            speedMeterR = speedMeterR + 1;            

            digitalWrite(speedMeterL, HIGH);            
            digitalWrite(speedMeterR, HIGH);                         

            delay(150);                 
        }        
    }     
    else if(keyData == KEY_F2) 
    {             
        if(speed > 30) // make sure you are not going too slow                 
        {                         
            speed = speed - 20; // slow down            

            speedMeterL = speedMeterL + 1; //turn off two outer LEDs            
            speedMeterR = speedMeterR - 1;            

            digitalWrite(speedMeterL, LOW);            
            digitalWrite(speedMeterR, LOW);             

            delay(150);                 
        }       
    }    
}

Step 8

Video

Not sure about the lesson or want to make sure you have the right code? Watch the video!

This lesson works with:

Grade level:

Approx. time required:

CSTA

NGSS

CCSS