Thermostat logic help, simple

Forum 2005-2010 (read only) Software Syntax & Programs
1

Hello,

I'm using my arduino to control a fan when the humidity drops below a certain point.

Currently my logic is this with humidity measured every 30 seconds:

if (humidity < 65)
  {
    digitalWrite(transistorPin, HIGH);
  }
  else
  {
    digitalWrite(transistorPin, LOW);
  }

This is nice because it maints a rock solid 65%, but the fans run almost every 30 seconds which i want to avoid.

I'd like the fans to run more efficently like a furnace in a home where it mantains a range, say turn on when temp < 65* and off when >=68*. This seems very simple but I am not sure how to approach it in C.

Any advice is appreciated!

Thanks,
Jacob

2

Wouldn't it be just

if (humidity < 65)
  {
    digitalWrite(transistorPin, HIGH);
  }
  else if (humidity >= 68)
  {
    digitalWrite(transistorPin, LOW);
  }
3

Thanks!

Given your code, the pin would not go LOW at say, 66?

4

That's right.
IT will turn on when humidity drops below 65 and then stay on until humidity exceeds 68, and then turn off.