I am new at DIYer and want to build a home automation IoT platform that can water plants. I want to use the Raspberry Pi 3 as the platform and connect a soil moisture sensor, photo diode and Atmospheric Sensor Breakout. I will power an aquarium pump with 120 VAC that will be turned on and off with a Powerswitch tail 2. To get some info on the sensors I want to equip my design with a I2C OLED display. The design is included below. The Raspberry Pi will be connected using a GPIO Cobbler board.

Did I make any rookie mistakes? Especially on the I2C wiring.

The fritzing file can be downloaded here.


  • And your question is?
    – Milliways
    Commented Mar 13, 2016 at 2:29
  • Any wrong wiring?
    – Stereo
    Commented Mar 13, 2016 at 2:35
  • See raspberrypi.stackexchange.com/tour "Focus on questions about an actual problem you have faced. Include details about what you have tried and exactly what you are trying to do."
    – Milliways
    Commented Mar 13, 2016 at 2:39
  • I was trying to get some input before ordering all the parts and/or frying my raspberry
    – Stereo
    Commented Mar 13, 2016 at 2:58
  • There is no reason those parts can't be connected properly. I.e. no reason to delay purchase. The I2C stuff seems okay. The ADC isn't connected to the SPI bus.
    – joan
    Commented Mar 13, 2016 at 10:06

1 Answer 1


the wiring could be really difficult and when you are dealing with high power ac at the same time its possible you can damage your pi or sensor.

i personally use this raspberry pi i2c adapter( using this adapter you can wire really easy and isolate rest of your pi from rest of circuitry) . i chose i2c communication because using this i can chain lot of devices.

now we have taken care of pi side lets move to rest of your circuit. you can use a high accuracy i2c ADC using which you can read soil moisture. for humidity, temp and pressure i will recommend use CPS 120. its a really low cost and high accuracy. you can get this with a i2c port form the same company you get i2c adapter for PI. so you can plug directly in to i2c port.

now lets move to pump control for that you can use a i2c relay board which will plug directly into pi adapter and you dont have to worry about any wiring and frying your pi.

you can get i2c oled screen from ebay. they already come with i2c pin. so you can connect with them with pi using a basic i2c cable.

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