Flight Controller with Analog Read

Remember programming your IR sensors? To read the sensors’ values, you used digitalRead({your pin number here}). You’re going to use a similar command for your joysticks! That command will look like:

analogRead({your pin number here});

• analogReadreads the sensor value with a range from 0 to 1023.
• The pin number specifies which sensor you want to be read.

Back to analogRead()! You’re going to use analogRead() to read your joysticks’ values. If you used the Building the Remote lesson to wire your remote control, your joysticks should be connected to pins 22 through 25. Check our Smart Inventor Pin-Out Guide if you’re still not sure!

Your code to read all of your joystick values would look like this:

#include <CoDrone.h>

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

void loop() {
  int yaw = analogRead(22);
  int throttle = analogRead(23);
  int roll = analogRead(24);
  int pitch = analogRead(25);
}

Pseudocode:

• Include the CoDrone library.
• Begin communication at a baud rate of 115200.
• Set the yaw variable to read and get the value for pin 22.
• Set the throttle variable to read and get the value for pin 23.
• Set the roll variable to read and get the value for pin 24.
• Set the pitch variable to read and get the value for pin 25.

Each of your joysticks has two sets of wires coming out of it, making four inputs. One set reads the left and right movement of your joystick, while the other set reads the up and down movement.

For an example of what your joysticks are seeing, look at the throttle joystick, which is connected to pin 23. Since analog values range from 0 to 1023, pushing your throttle joystick all the way up will save its value as 1023, while pushing it down will save the value as 0. Leaving the throttle joystick in the middle would save its value at about 512, which is around halfway between 0 and 1023.

Right now you have your roll, pitch, yaw, and throttle variables reading and getting the values for their pins, but those values are going to be between 0 and 1023. For your CoDrone’s remote control, they need to be translated to a range of -100 to 100. Luckily, this doesn’t take giant math equations — just a scale change!

Wait, what?

Basically, you need to use the values from one scale and re-map them to another scale. In the case of your joysticks’ values, you would need to translate them from the 0 – 1023 scale to the -100 – 100 scale. 0 would turn into -100 since they’re both the lowest values, 1023 would turn into 100 since they’re both the highest values, and 512 would be 0 since they’re both in the middle. The scale change would look a lot like the picture below.

The only problem is that you can’t just input new values in Arduino and hope it turns out well. What you can do instead is use the analog scale change function:

CoDrone.AnalogScaleChange()

• What goes between the parentheses is the number that you want to be remapped from the 0 – 1023 scale to the -100 – 100 scale.
• Once this function is used, the values that are returned will be from -100 to 100.

The easiest way to use this function is to combine it with the variables you wrote earlier. For example, using it with your yaw variable would look like this:

CoDrone.setYaw(CoDrone.AnalogScaleChange(analogRead(22)));

Your joysticks’ horizontal motion works somewhat differently than their vertical motion. That range is from 1023 to 0, instead of the other way around. Look at the pictures below to help you out! Since movement to the left is associated with negative numbers, you will need to multiply the lines for yaw and throttle by -1. This will convert the analog values correctly.

This is what it will look like in your code:

CoDrone.setYaw( -1 * CoDrone.AnalogScaleChange(analogRead(22)) );    
CoDrone.setThrottle( CoDrone.AnalogScaleChange(analogRead(23)) );   
CoDrone.setRoll( -1 * CoDrone.AnalogScaleChange(analogRead(24)) ); 
CoDrone.setPitch( CoDrone.AnalogScaleChange(analogRead(25)) );

Your final code should look something like this:

#include <CoDrone.h>

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

void loop() {
  byte bt8 = digitalRead(18);
  byte bt4 = digitalRead(14);
  byte bt1 = digitalRead(11);

  if (PAIRING == true){  

    CoDrone.setYaw( -1 * CoDrone.AnalogScaleChange(analogRead(22)) );    
    CoDrone.setThrottle( CoDrone.AnalogScaleChange(analogRead(23)) );   
    CoDrone.setRoll( -1 * CoDrone.AnalogScaleChange(analogRead(24)) ); 
    CoDrone.setPitch( CoDrone.AnalogScaleChange(analogRead(25)) ); 
    CoDrone.move(ROLL, PITCH, YAW, THROTTLE);   

  }

  if (bt1 && !bt4 && !bt8){
    CoDrone.emergencyStop();
  }
}