How can i tell a DC motor to turn on if a servo is facing a specific location?

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1

what i am trying to do is use an object detector to make a servo move to a specific location and then once it does turn on a DC motor. The project is an arrow and a DC motor with a fan attached to a servo and the goal is for the arrow and motor to point at someone when they get close to the object detector and then turn a fan on with the DC motor. So far i have been able to make the servo move to the specific location based on what object detector is reading less than 40 (i have 2 object detectors) but i can't for the life of me figure out how to turn the DC motor on once the servo moves. I feel like it needs to be done with an IF statement but nothing i can think of is working.

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#include <Servo.h>

//this is the pin connected to my servo
int servoPin=9;

//since the servo is not included by deafult this is how i tell my arduino what the servo is.
Servo myServo;

//i need to start it in a position
int servoPosition=20;

long duration1; // long is just a larger variable. it stores more numbers. this will record the time it takes to travel
int distance1; //this is what i will use ro define the distance
int triggerPin1=A1;
int echoPin1=A0;
int Pos1=80;

long duration2; // long is just a larger variable. it stores more numbers. this will record the time it takes to travel
int distance2; //this is what i will use ro define the distance
int triggerPin2=A8;
int echoPin2=A9;
int Pos2=150;

//------------------------------Motor setup

//L29 pin1
int speedPin=2;
//L29 pin2
int directionPin1=3;
//L29 pin7
int directionPin2=4;
//this number will indicate speed and must be between 0-255
int motorSpeed=255;
int motorSpeed2=0;

void setup() {
Serial.begin (9600);

//this is how you assaign the servo to a pin. you take the item you defined as a servo to your arduino and tell it what pin that servo is connected to
myServo.attach(servoPin);

pinMode (triggerPin1,OUTPUT);
pinMode (echoPin1, INPUT);

pinMode (triggerPin2,OUTPUT);
pinMode (echoPin2, INPUT);

pinMode(speedPin,OUTPUT);
pinMode(directionPin1, OUTPUT);
pinMode(directionPin2, OUTPUT);

}

void loop() {
//how to start the motor on something. in this case starting it in the off position
digitalWrite(directionPin1, HIGH);
digitalWrite(directionPin2, LOW);
//we need to tell the speed pin what speed to go. so we assaign it a value 0-255
digitalWrite (speedPin, motorSpeed);

digitalWrite (triggerPin1, LOW);
delayMicroseconds(2); //this is how i set my output to low and make sure noting is being sent from it to start.

//this is how i send out a pulse
digitalWrite (triggerPin1, HIGH);
delayMicroseconds (10);
digitalWrite (triggerPin1, LOW);

//this is how i tell my echo pin to read the pulse thats sent out once it returns
duration1 = pulseIn(echoPin1,HIGH);
distance1=duration1*0.034/2;

Serial.print ("distance1: ");
Serial.println(distance1);

//--------------------------------------------------------------------------------------
digitalWrite (triggerPin2, LOW);
delayMicroseconds(2); //this is how i set my output to low and make sure noting is being sent from it to start.

//this is how i send out a pulse
digitalWrite (triggerPin2, HIGH);
delayMicroseconds (10);
digitalWrite (triggerPin2, LOW);

//this is how i tell my echo pin to read the pulse thats sent out once it returns
duration2 = pulseIn(echoPin2,HIGH);
distance2=duration2*0.034/2;

Serial.print ("distance2: ");
Serial.println(distance2);
//--------------------------------------------------------------------------------------

if(distance1>40 && distance2<40){myServo.write (Pos1);}
else if (distance1<40 && distance2>40){ myServo.write (Pos2);}
else{myServo.write (servoPosition);}
}
</>

2

Have you written a test program that ONLY turns the motor on and off? How are you controlling the power to the fan? A relay or a MOSFET? How are you powering the fan?

1 Like
3 
  if(distance1>40 && distance2<40)
  {
    myServo.write (Pos1);
    TurnMotorOn();
  }
  else if (distance1<40 && distance2>40)
  { 
    myServo.write (Pos2);
    TurnMotorOn();
  }
  else
  {
    myServo.write (servoPosition);
    TurnMotorOff
  }

The motor functions would look like this:

void TurnMotorOn()
{
  digitalWrite(directionPin1, HIGH);
  digitalWrite(directionPin2, LOW);
  digitalWrite (speedPin, 255);
}

void TurnMotorOff()
{
  digitalWrite(directionPin1, LOW);
  digitalWrite(directionPin2, LOW);
  digitalWrite (speedPin, 0);
}
1 Like
4

ahh I got it. The problem with all the attempts I was doing was I wasn't including what the DC motor should do in my 'else if' and 'else' statement. I had only included it under my first IF statement.

I spent like 4 hours trying to figure this out
Haha
Thank you for the response!

5

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