Arduino with lots of humidity and temperature sensors

Hi. I’m interested in building a home monitoring system, primarily for measuring humidity and temperature. The project calls for a 20 to 30 sensors, many of which will be embedded in the walls and ceilings and not accessible once installed. Real time data and data logging required.

I’m interested to see if there is an Arduino based solution for this. My thoughts are:
Arduino Mega* board.

  • Either lots of sensors connected to each digital input.
  • Or, I2C or SPI bus sensors.

My initial research tells me directly connected H/T sensors to digital inputs is simple but requires a lot of wiring. A bus system might be possible but the sensors are more expensive.However… In order to reduce total wiring length and complexity, can I connect and read up to 30 humidity/temp sensors on a bus with the Arduino?

If anyone can give me a bit of guidance, that would be great. I’ve never tried building and Arduino system before, but this project seems like a good one to get into it.


Hey Anthony,

This sounds like quite an interesting project and I think there would be a number of different ways you could tackle it. With regard to the wiring, both options would require a lot as you would have to connect each sensor to the bus. The dirty and cheap way would probably be to use a temperature sensor like this along with your Arduino.

I hope this helps.

Thanks Gordon. I think I might go with the simple DHT22 sensors and discrete wiring to each sensor from the Arduno Mega.

Does anyone have experience with many runs of long cable and potential for issues with voltage drop or poor signal?

Hi mate, have you considered using a bunch of Mini D1s instead? I reckon it will end up costing about the same once you include all effort with cabling and all. You would also be ok if one room failed as each room/sensor could be completely independent.