Coert Vonk's OPNpool Integrates Your Pool Controller System with Home Assistant via MQTT Messages

Designed to communicate with existing pool management systems via RS485, the OPNpool is an open source upgrade.

Embedded software engineer and educator Coert Vonk has released a platform designed to turn an Espressif ESP32 into a fully-functional pool controller, ready for integration with Home Assistant via MQTT: OPNpool.

"Owning a backyard pool means learning about chemicals, and dealing with covers, vacuuming, brushes and adjusting the thermostats and circuits," Vonk explains. "The OPNpool integrates the functionality of a traditional Pool Controller into the modern smart home. It keeps tabs on the status of the connected controller, pool pump and chlorinator. This provides not only a more convenient solution than physically interacting with the pool equipment, but the ability to create automations that run the pump for a duration depending on the temperature."

The heart of the OPNpool is a carrier board for a Wemos LOLIN D32 ESP32-based development board or compatible, housed inside a waterproof chassis β€” exposed electricals and pools not mixing terribly well. The rest of the hardware, however, can be off-the-shelf.

"Thanks to the people that reverse engineered [the] RS485-based protocol, OPNpool can listen into the communication between the pool components," Vonk explains. "The ESP32 shares the resulting state information as JSON/HTTP and can publish it using MQTT. Last but not least, it integrates seamlessly with Home Assistant thanks to MQTT Discovery."

While Vonk started work on the OPNpool project back in 2014, and has been testing it with a Pentair SunTouch controller, IntelliFlo Pump, and IntelliChlor salt-water chlorinator, the maker has only now decided to make the project available to the public under an open source license.

As released, the software provides a web interface with visual status reports on everything from pump and chlorinator status to set schedules, allows for easy configuration, can be updated over-the-air, requires no separate power adapter, and integrates with Home Assistant or other MQTT-capable smart home systems.

The full source code and instructions can be found on the project's GitHub repository under the reciprocal GNU General Public License 3, with additional information available on Vonk's blog.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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