Trying to make an output only HIGH if an input is HIGH

Projects Programming
1

Hi,
I have a arduino micro and I am making a project that requires a motor to only run when an Input is HIGH. The problem is the motor will just go on as soon as I connect it to the arduino even if the input is LOW and it just stays on until I disconnect it. Here is my code and maybe someone can help me out here.

int motorPin = 5;
int switchIn = 8;
int val = 0;
void setup() 
{ 
  pinMode(motorPin, OUTPUT);
  pinMode(switchIn, INPUT);
 
}

void loop() 
{
 val = digitalRead(switchIn);
 
 switch(val) 
 {
   case HIGH:
     digitalWrite(motorPin, HIGH);
     break;
   case LOW:
     digitalWrite(motorPin, LOW);
     break;
    default:
      digitalWrite(motorPin, LOW);
 }
}
2

How is your switch wired up?
Is one side connect to pin 8 and the other to GND or through a resistor to +5V.
If it connected to GND then you need to turn on internal pullup on pin 8 and reverse the switch logic (LOW = Pressed, HIGH = Released)

3

How is your switch wired up?
Is one side connect to pin 8 and the other to GND or through a resistor to +5V.
If it connected to GND then you need to turn on internal pullup on pin 8 and reverse the switch logic (LOW = Pressed, HIGH = Released)

I don`t know how to reply to comments so I did this...

I have the switch wired from my batteries to pin 8.

4

I have the switch wired from my batteries to pin 8.

A switch has two legs. Where does each one connect to? Is the battery ground connected to the Arduino ground? What else is connected to pin 8? Draw a picture!

5

PaulS:

I have the switch wired from my batteries to pin 8.

A switch has two legs. Where does each one connect to? Is the battery ground connected to the Arduino ground? What else is connected to pin 8? Draw a picture!

Well i dont think im going to draw a picture but one side of the switch connects to the batteries and the other side connects to pin 8. And yes the arduino grounds to the batteries.

6

Well there's the problem, you have a floating pin 8.

Add a resistor (in the range 1k to 10k or so) from pin 8 to ground.

You missed a trick - if you had wired the switch between pin 8 and ground,
and initialized it thus:

  pinMode (8, INPUT_PULLUP) ;

You wouldn't have needed the resistor (but you would need to reverse the
sense of the logic).

7

Thank you so much this worked perfectly. I only wish I had posted this sooner!

8

Your code is unnecessarily long and there is no need for a default case, there are only 2 possibilities.

digitalWrite(motorPin, digitalRead(switchIn));

will do the same thing, mind you so will a length of wire :slight_smile:

Rob