Newbie with an Automation PHAT ADC question


#1

Hi All -
So I just got my Automation Phat. I’m going to use it to control my swimming pool heater, using the relay to switch the heater on/off. I was going to use a DS18B20 as the temperature sensor, but since the heater already has a built-in dual thermistor, why not try using it with the ADC on the phat? So I want to understand what readings to expect from the ADC. Is that the voltage being read on the pin? If the ADC handles up to 24v, can I expect readings between 0-24 from the pin? Just trying to understand what kind of voltage I should put on the thermistor and what kind of reading I should expect.

Thanks in advance,
HB


#2

The ADC actually reads between 0 and 3.3v and uses a voltage divider that divides 25.85v down to 3.3v. This is taken care of by the Python library, though, so as long as the voltage you put into the 24v tolerant pins is between 0v and 24v you should get a fairly accurate reading in the code of 0.0 to 24.0.


#3

Thanks for the quick response. So are you saying that if I use the python library I’ll only get a reading between 0 to 3.3? Or is there a call I can make to get the 0.0-24.0 range?


#4

If you use the Python library, the reading will be adjusted to 0 to 24v for you.