Matrix user forums

Posted: **Thu Jan 05, 2012 5:06 pm**

Hi, all

Im still working on my aquarium controller, everything works perfectly but one thing I can't figure out thats why I need your help.
For the temperature controller section of the software I need to make something like hysteresis so that the heater doesn't kick in on every change of temperature.

If I set the upper limit of the temperature to: 22.4
My goal temperature to: 22.0
and my lowest temperature to: 21.8

So that the heater kicks in when the temperature is 22.8 or below and stops when temperature reaches 22.1 or above.
I dont know on howto approach this problem. hope somebody can explain it to my.

Regards Jordy

Posted: **Thu Jan 05, 2012 5:30 pm**

Hi

I would try the following, or something similiar

if (new_temp-old_temp) > 0 then temp_up = 1
if (new_temp-old_temp) < 0 then temp_up = 0

if new_temp <=22.8 AND temp_up = 0 then heater on
if new_temp >=22.1 AND temp_up = 1 then heater off

Goodluck

Gary

Posted: **Thu Jan 05, 2012 5:32 pm**

I think you just need to do the following every few seconds:

Code: Select all

  read temperature

  if (temperature < MIN_TEMPERATURE)
    turn heater on
  end if

  if (temperature > MAX_TEMPERATURE)
    turn heater off
  end if

Posted: **Thu Jan 05, 2012 6:47 pm**

Thanks steve and gary for your quick reaction,

The solution steve has works best for me and tested this and works perfectly thanks for that.

Regards Jordy

Matrix user forums

temperature controll

temperature controll

Re: temperature controll

Re: temperature controll

Re: temperature controll