Communication and Pairing

When you write programs, make sure that you use words that the computer knows! For example, if you want your CoDrone to fly upwards, you might want to write something like this:

void setup(){

    Takeoff!!
    Hover for 3 seconds!!
    
    Ok, now land.

}

void loop() {

}

One problem: your computer doesn’t know what Takeoff!! and Ok, now land. means! Instead, you would need to write something like this:

#include <CoDrone.h>

void setup(){
  CoDrone.begin(115200);
  CoDrone.pair();
  CoDrone.takeoff();
  CoDrone.hover(3);
  CoDrone.land();

}

void loop(){
  
}

Just like how you might read books written in English, computers read code from top to bottom. In this program, the first line that the computer would read is #include <CoDrone.h>, and the last line that the computer would read is CoDrone.land();.

#include <CoDrone.h>

void setup(){
  CoDrone.begin(115200);
  CoDrone.pair();
  CoDrone.takeoff();
  CoDrone.hover(3);
  CoDrone.land();

}

void loop(){
  
}

Although computers read code much faster than we can (more on that below), they can only read one line at a time. This means that only one command can be executed at a time.

Keep in mind what we just said: computers can read extremely fast — like hundreds of thousands of times per seconds fast. That speed would put The Flash to shame! Even though the program is being read at only one line at a time, it might feel like it’s happening all at once on your end because of the speed at which a computer can read a program.

The first thing you need to do at the beginning of every CoDrone program is include the CoDrone library:

#include <CoDrone.h>

Wait…what’s a library again?

A library is a saved set of functions, variables, and other resources that can be used in your code. For example, if you know that you always want your CoDrone to take off by throttling up slowly for 3 seconds, you can save time and memory by saving this as a function in a CoDrone library! Instead of telling your CoDrone to “throttle up slowly for 3 seconds” every time, you can create a function, or use one that’s already in the library, to tell your CoDrone “takeoff”. Your CoDrone will then perform the “takeoff” function!

Any code that starts with CoDrone._____is a function in the CoDrone library.

Still not sure about libraries? Learn more on the Arduino website.

Once you include the CoDrone library at the top of your code, you can use all of the CoDrone functions in the rest of your program!

The first function you need to use is CoDrone.begin();, which will start the connection to the Bluetooth board. Inside of the parentheses is the baud rate, which is the bits per second that communication will travel. This line of code should be in void setup(), and the baud rate should be 115200 since the Bluetooth board uses that rate for serial communication.

This is what your code should look like:

#include <CoDrone.h>

void setup() {            

  CoDrone.begin(115200);         

}

The next thing you need to do is pair with your CoDrone! There are a few ways to do this which we’ll go over in another lesson, but for now, the easiest thing to do is use the function CoDrone.pair().

This next part is important. Read it as many times as you need to!

pair() will just pair with whichever CoDrone you were last paired to. However, if this is your first time using the remote and you haven’t paired with a CoDrone with this particular remote, it will just pair with the first available CoDrone it finds, then lock in with that CoDrone. From that point on, it will always try to pair with that CoDrone. If you’d like to pair with a new drone, you can check out the next lesson: Unlocking a Remote-CoDrone Pair.

Since computers read code from top to bottom, this function needs to be underneath your baud rate.

void setup() {            

  CoDrone.begin(115200);          
  CoDrone.pair();

}

Student Tip:

This will not make your CoDrone fly! Sorry! This will just establish a Bluetooth connection between your CoDrone and your Bluetooth board.

Instructor Tip:

This is what your final code should look like:

#include <CoDrone.h> 


void setup() 
{ 

CoDrone.begin(115200); 
CoDrone.pair();

} 

void loop() { 

}

Challenge: Friends forever

Try to pair with your CoDrone with the code you just wrote! If you’ve successfully uploaded and run your code, you should hear a beep as it searches for the drone, and then a chime once it’s paired. The green light on the back of the CoDrone flashes when it is unpaired, and becomes a solid green when it is paired.

Instructor Tip: Remember, if a remote has ever paired with another CoDrone using pair()(with no parameters), then it’s been locked in to that CoDrone. Running the final pairing code here will only pair with the CoDrone the remote has been locked in with. If it’s the very first time, then it will pair with the first CoDrone it finds, then lock in to that CoDrone. If you want to pair a remote with another CoDrone, you’ll need to run through the unlocking process, which is covered in Unlocking a Remote-CoDrone Pair.