The Smarter Sprinkler Irrigation System

Project Description:

The scope of this project is to reduce water waste from broken sprinkler heads, alert maintenance personnel for repair, and to provide a web user interface to remotely program considering local weather variables.

Bill of Materials:

Microchip:

AVR-IoT Cellular Mini #EV70N78A

Adafruit:

Adalogger FeatherWing - RTC + SD Add-on For All Feather Boards[ID:2922]

64MB Micro SD Memory Card[ID:5249]

Amazon:

24V AC to 12V DC Convertor

DFRobot:

Gravity: Analog Water Pressure Sensor SEN0257

Solenoid Valve - DN20 FIT0617

Gravity: Liquid Flow Sensor (G1/2) SEN0550

Lowes:

Orbit 4-Station Digital Indoor/Outdoor Irrigation Timer Model#27894

Orbit 0.75-in Plastic Electric Inline Irrigation Valve #57460P

Orbit 1-ft -15-ft Quarter-circle Spray 2-in Pop-up Spray Head Sprinkler #80329

Orbit Water Pressure-Gauge #91130

1” PVC pipe

Various PVC pipe fittings

PVC cleaner/primer/cement

Instructions:

The first thing I did was build a test irrigation system with the parts from Lowes and DFRobot. Next, I opened the Orbitz Timer to reverse engineer it to interface with the AVR-IoT Cellular Mini. I found that the sprinkler control circuit consisted of a 24 vac power supply, a microcontroller board, and a sprinkler valve control board. The sprinkler valves are actuated with a MAC97A6 Q4 Triac on the control board. The datasheet of the MAC97A6 states it is “intended to be interfaced directly to microcontrollers, logic integrated circuits and other low power gate trigger circuits.” With that information my design shifted to replacing the Orbitz microcontroller with the AVR-IoT Cellular Mini and directly controlling the control board with it and removing the Solenoid Valve - DN20 FIT0617 as the AVR can shut down the system through the irrigation solenoid valves.

The AVR-Iot Cellular Mini is powered from the Orbitz power supply to the 24V AC to 12V DC Converter to USB. The Adaloger was added to provide a real time clock to wakeup the AVR for irrigation control and cellular communication.

Several tests were conducted with the Orbit Water Pressure-Gauge, Gravity: Analog Water Pressure Sensor, and the Gravity: Liquid Flow Sensor. The Orbitz gauge was used as a visual analog control. My tests concluded that just using the Gravity: Analog Water Pressure Sensor provided the data to detect the broken sprinkler head event. The Liquid Flow Sensor could also provide the necessary data however it has internal moving parts making it potentially less reliable for long term use.

To get familiar with the AVR-IoT Cellular Mini I implemented the GPS tracker example found here: https://iot.microchip.com/docs/arduino/examples/GPS%20Tracker/Intro I used my home Debian server to host the Flask web server.

Conclusion:

I experienced a catastrophic failure that I was unable to recover from in the time given. When probing the Orbitz control board I shorted that board as well as the AVR-IoT Cellular Mini. The integration of the Gravity: Analog Water Pressure Sensor to any irrigation control station will reduce water waste due to broken sprinkler heads. By adding the AVR-IoT Cellular Mini it is possible to remotely control the irrigation system and alert maintenance personnel of issues.