Autogrow has released open source files for building an “OpenMinder” root zone monitor HAT and API for the Raspberry Pi that manages water, pH, and nutrient usage in hydroponic farming.

Auckland, New Zealand based AgTech firm Autogrow has launched an OpenMinder project for DIY water management and root zone monitoring by releasing schematics and other open source files for building a Raspberry Pi HAT add-on board. The system, which came to our attention from a bizEdge New Zealand story, is designed in response to increasing restrictions on water usage and pesticide and fertilizer runoff. A commercial version is due in Q4 2019.

OpenMinder (left) and dashboard sensor readout
(click images to enlarge)

The OpenMinder board is designed for small hydroponics growers, educators, and agricultural technology researchers looking to reduce water usage and waste runoff. “It’s also the perfect product for an NGO to fund for countries whose farmers need a subsidized (or free) water run-off monitoring system,” says Autogrow.


OpenMinder diagram
(click image to enlarge)

Rootzone monitoring is the process of measuring the nutrient, pH, and water volume supplied to the plant via irrigation and comparing it with the runoff from the plant. “You may be able to modify your irrigations to increase yield by preventing crop loss and disease associated with under or over shooting the runoff ratio,” says Autogrow.

Together with a Raspberry Pi 2 or 3 SBC, the HAT board enables connections to sensor probes for nutrients, pH, and water flow that are deployed in sample pots (see diagram above). Nutrient levels derive from an EC (electrical conductivity) probe, which measures dissolved salts.

OpenMinder HAT board schematics (left) and closeup on Raspberry Pi pinout connections
(click images to enlarge)

The system is designed to use Autogrow’s EC Probes, which are also used on its $1,500 IntelliDose system. IntelliDose is designed for auto-dosing up to four irrigation systems with nutrients.

In addition to the HAT board and a Raspberry Pi, the following components are required to build a root monitoring system:

• 2x Autogrow Intelligent EC Probes
• 2x pH Probes (any with a BNC connector should work)
• 2x tipping buckets (pluviometers)
• 2x container to catch the water in for measurement (sample pot)
• 1x CF/EC buffer calibration solution
• 1x pH4 buffer calibration solution
• 1x pH7 buffer calibration solution

The Debian based binary API uses REST API v1 with API access via HTTPS. Data is received via JSON. The HAT board is licensed under a Creative Commons BY-NC-SA license and the API is posted on GitHub.

 
Further information

Schematics for the OpenMinder HAT board are available for free download. The board is slated for a commercial release in Q4 2019. More information may be found in Autogrow’s OpenMinder announcement and blog post tutorial pages. The GitHub page may be found here.