Automation phat compatible sensors


#1

Hi,
love the automation phat and want to put it to good use…can you tell me what kind of sensors work best with it, as I’d like to take advantage of the three INPUT pins, the ADCs scare me a little?

I’m talking specifically about temperature, humidity, pir sensors, even if you could provide a link to some on your site that you’d recommend & are compatible with the Automation phat.

Thanks again,

Paul :)


#2

For temperature you could use the TMP36, which you can power at 3.3v. It then supplies an analog output that the 3.3v analog pin on Automation HAT could read.

I believe all the humidity/pressure sensors we stock are on i2c breakouts- meaning they would run quite happily alongside Automation HAT .

Our Hydrogen/LPG and Carbon Monoxide sensors also output an analog signal, but due to the voltage divider that makes the other 3 analog pins on Automation HAT 24v tolerant you might have trouble getting a good reading out of them.

The 24v ADC pins actually take 0v to 25.85v, dividing that down to 0-3.3v. That means if your sensor outputs 0-5v then only one fifth of the usable range of the ADC is used. Since it’s an 11bit ADC (if i remember correctly) which has a full range of 0-2047 that means you can only read about 409 possible values from a 5v analog sensor on these pins.

Depending on the sensitivity of the sensor, and the range at which the property you’re measuring varies, this might not be so useful!

TLDR: You can only really use one 3.3v analog sensor on Automation HAT unless you don’t mind losing precision or getting really technical!

i2c sensors, though, you can use dozens- theoretically- as long as they’re wired into the i2c bus and have a unique address.


What sits between Automation Hat analog inputs and the ADS1015?