I created a PH and Temperature sensor to use for my hydroponics system. This is right now streaming back to io.adafruit.com.
Right now, the platform handles PH, air temperature, and water temperature. The goal is to add O2 absorption and conductivity. As well as stream the data to an Azure IoT Hub. That hub will then be able to store certain data in data storage, trigger events, etc.
NodeMcu ESP8266 ESP-12E WIFI Development Board
DS18B20 Temperature Sensor (water proof for H2O temperature readings)
DS18B20 temperature sensor that is going to be soldered to the project board for airtemp
ADS1115 16bit ADC to convert the analog signal from the PH sensor to digital
DC to DC voltage converter to handle the required 5v for the PH sensor (the ESP8266 is 3.3v)
Cleaned up my prototype a bit by moving it off the breadboard and soldered to a smaller perf board. Also added some screw down terminals to connect the external sensors.
One problem is that now the PH sensor is always reading a PH of about 2.5. Either I have something wrong in the wiring (I dont think so), or the probe went bad. I heard that these probes can be a bit weird. I am going to try to attach to a Leonardo Arduino and see if I get different results there. (ie. bypass my ADC converter and just read the analog directly on a real arduino).
The results of the build are below. More to come later.