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I am having a problem implementing a the digitalRead() function in arduino uno.I want digitalRead to return 0 when nothing is connected and return 1 when it is connected to +5 volt.But seems like digitalRead returns random values when it is not connected to anything. I have kind of solved the problem by a small piece of code to stabilize the value i'll attach the code here but if any other solution is avalable..Please help.

The function is as follows:-

bool getValue()

{

String k="";

if(digitalRead(3)==HIGH)

k="HIGH";

else

k="LOW";

bool f=true;

for(int i=0;i<1000;i++)

{
String z;

  if(digitalRead(3)==HIGH)

  z="HIGH";

  else

  z="LOW";


  if(k!=z)

  {

    f=false;

    break;

  }

}


if(f==true)

return true;

else

return false;

}
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1 Answer 1

Reset to default
3

The solution is called a pull down resistor and it's exactly the same as when you are using a button - the button is what connects the pin to +5V. The pull down resistor (usually around 10kΩ) connected to ground is what makes the pin read LOW at other times.

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2
  • 2
    Do you (original poster) really need it to read 0 when disconnected? The Arduinos have a built-in pull-up resistor which you can easily enable (arduino.cc/en/Tutorial/DigitalPins), meaning it will read 1 when disconnected. Your external device then has to pull the line to 0v to signal something. This is a very common way of doing things. Commented Dec 16, 2016 at 12:00
  • Thanks Mark... I'll implement it in that manner..Thanks again Commented Dec 16, 2016 at 12:52

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