Building Your Own Hardware

WARNING

This project will not work on all spa pools. Refer to the compatibility page to understand if your spa pool is compatible with this project.

DANGER

It is really important to note that shorting pins 7 and 8 on the EXP1 port will cause the spa controller to short, and cause irreparable damage to the controller. This is why it is important to build your own hardware with care, and to test it thoroughly before connecting it to your spa pool. We've already heard of at least two people who have had to replace their spa controllers due to this mistake. If you want to reduce the risk of damage, consider purchasing a pre-built PCB instead.

Spa Pool Connection Overview

On spa pools containing SpaNet SV and SV Mini controllers, there exists a port labeled EXP1 or EXPAND1 port. This is a standard RJ-45 plug, with the following output coming from the controller on each of the pins:

Pin	Controller	WiFly Adapter
1	Health Led	Pass through
2	GND	Pass through
3	Not used
4	Not used
5	TX	RX
6	RX	TX
7	GND	GND
8	12V	12V

Because the spa is outputting 12V over this connection, we can build our controller with no need for an external power connection - all we need to do is convert the 12V down to a 3.3V voltage suitable for our ESP32 chip. We then use pins 5/6 to communicate with the controller, using our custom firmware.

Microcontroller Selection

Our pre-built PCBs use either the ESP32-S3 (v1) or the ESP32-C6 (v2). A minimum of 8 MB of flash memory is required to ensure compatibility with our firmware.

Flash size is often indicated in the part number as -N8 (8 MB) or -N16 (16 MB). For example, our v2 board uses an ESP32-C6-WROOM-1-N8 microcontroller.

If you would like to use the pre-compiled firmware, you must use either an ESP32-S3 or ESP32-C6 with at least 8 MB of flash memory. If you would like to use a different ESP32 variant, you will need to compile the firmware yourself using PlatformIO. See Building Firmware from Source for instructions.

Components

The table below lists a few options for purchasing the required components. AliExpress is typically cheaper but has a much slower delivery, compared with the more expensive Core Electronics (based in Australia), with their faster delivery times.

Component	Store links	Comments
ESP32-C6-N8	AliExpress / Core
RJ45 connector	AliExpress / Core	Get a 'H Type+DIP Pins'.
Buck converter	AliExpress / Core	Get a '5-40V to 3.3V' converter.
330 ohm Resistor	AliExpress / Core	You need two 330 ohm resistors.

Beyond these key components, you may want to buy some protoboards, breadboards, pin headers, cables, etc to build your device. Some useful links include: