Testing PH/Temperature sensor

I have progressed on my PH sensor project.  I have added temperature sensors (Dallas DS18B20) to measure air-temp and water-temp to augment the PH sensor.  Next will be the addition of O2 absorption as well.
I am using the following:

  1. ESP8266 wifi board (for the microcontroller)
  2. 1x DS18B20 temperature sensor that is water proof for watertemp
  3. 1x DS18B20 temperature sensor that is going to be soldered to the project board for airtemp
  4. 1x ADS1115 16bit ADC to convert the analog signal from the PH sensor to digital
  5. 1x DC to DC voltage converter to handle the required 5v for the PH sensor (the ESP8266 is 3.3v)
  6. 1x 5v Analog PH Sensor
  7. Visual Micro (yes, I am a visual studio user.  and I find that visual micro gives me much more than the Arduino IDE)

You can see the device at work.  NOTE the PH of the water is very acidic.  This is due to the fact that we had a lot of rain.  I have to get the PH back up to about 6 for the lettuce to be happy.

[youtube https://www.youtube.com/watch?v=gWC4SFbHO0Y]

After weatherproofing and hardening our prototype, we are then looking at feeding the data to an Azure IoT hub which we can then route that data to helpdesk, CRM, and field service systems for dispatching technicians to remedy any problems that could occur.  As well as have data for BI reporting.  Our integration tools for this type of thing can be seen at www.catalinatechnology.com

Azure Event Hub to Adafruit Bridge
Using PostMan to call the SOAP version of Catalina API for Dynamics SL


  1. Interesting, but I failed to find which ph sensor you were using. Thanks 🙂

  2. Hey I need help with connecting the pH sensor to the nodeMCU! I can’t get it, I would apreciate if you could give me your contact!

    • catalinatechnology
      July 26, 2017 - 9:46 am

      the PH sensor is a bit tricky since it requires 5v logic levels (and the nodeMCU is 3.3). The way I got around it is to use a ADS1115 to convert the analog signal of the PH sensor to digital. and then I also used a 3.3v to 5v DC to DC booster to power the PH sensor. I’ll see about getting you a schematic when I can pull the device out of my hydroponic garden later today.

    • do you resolved it now?

      • yes. I just had to provide 5v power to the sensor and use an analog to digital converter to convert to digital. I will try to dig up the code that I used.

  3. can you please share the code for ph sensor …

  4. i have connected ads1115 to nodemcu through I2C pins.. power supply is provided as 5v to nodemcu vin and ads1115 from same 5v source.. but am not able to get the proper ph value for 7 and 9 ph solutions… i have connected ph sensor module to A0 and offset calibration potentio meter to A1 pins of ads1115 … can you please share code and circuit,…

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