Unlocking a Remote-CoDrone Pair

We’ve talked a lot about functions in the past couple of lessons, but we haven’t fully defined them! A function is a set of code that is saved and given a name. For example, if you wanted to make a ham and cheese sandwich, the directions might look something like this:

If four of your favorite people also wanted ham and cheese sandwiches, the directions would be super long and repetitive without functions!

To shorten this, you can save the directions to make one ham and cheese sandwich and then name this new function “Make a Sandwich.” Now, if you wanted to make five ham and cheese sandwiches, the directions would just be “Make a Sandwich” written five times. Much easier!

In the CoDrone library, we used a function called pair(), which you used in the previous lesson to pair with the CoDrone. Like there are multiple ways to make a sandwich, there are multiple ways to pair with a CoDrone. You’ve already used the first way to run pair(): with nothing in the parentheses. Like we mentioned before, when you run pair(), it will just pair with the last CoDrone the remote was paired to. If the remote had never been paired with a previous CoDrone, it will pair with the first CoDrone it finds, and then lock in to that drone.

In the case that you want to pair with a different CoDrone, you can run pair() with Nearestas a parameter (side note: a parameter is a value in a function). This will look like pair(Nearest). This tells the pair() function how you want to run the function. Instead of using the default behavior, it will pair with the first CoDrone signal the BLE (Bluetooth Low Energy) board finds. This may or may not be the CoDrone that is closest to you!

Your code will look like this:

#include <CoDrone.h>

void setup(){
  CoDrone.begin(115200);
  CoDrone.pair(Nearest);
}

void loop(){
}

Upload this code to your remote, and when it’s finished, put the remote in run mode. When you run this program, it will pair with the first CoDrone signal it finds, so make sure to turn off all other CoDrones! When you hear a chime, it means your remote has paired with a CoDrone. Your CoDrone’s address will be saved to the EEPROM, or memory, located in the Smart Inventor Board. Think of this as the remote telling itself, “All right, the last CoDrone I connected to is this one right here!”

Now that you’ve run pair(Nearest)to tell the remote to pair with the first CoDrone signal it finds, it has committed that particular CoDrone’s address to its memory. You have a couple of choices for what you can do next:

• Keep running pair(Nearest) so you connect to the nearest CoDrone signal. This may or may not be the CoDrone you last paired with!
• Use pair() to lock your remote in with that particular CoDrone.

If you’re a fan of choice #2, upload the code below. If you’re experiencing deja vu, that’s because you saw this code in the last lesson.

#include <CoDrone.h>

void setup() {  
  CoDrone.begin(115200);  
  CoDrone.pair();
}
  
void loop() {

}

Once you’re back in run mode, make sure your remote and CoDrone are paired! These are the indicators of successful pairing:

• A chime playing from the remote
• Solid blue Smart Inventor Board lights (instead of pulsing pattern)
• A solid green tail light on the CoDrone
• A solid green light on the BLE board

But don’t take our word for it! If you want to double-check, turn on a few CoDrones and place them nearby. Next, reset your remote and make sure it doesn’t pair with any of the other CoDrones.

Instructor Tip:

At this point, if you’re pairing a remote to a new drone, we recommend re-labeling the remote and drone to have a matching number or code so you know which remote and drone are a pair.

Challenge: Find a new friend

Find a remote and CoDrone pair, and then find a second CoDrone. Program the remote to pair with the second CoDrone and then lock in with it.