softub-wifi

A project for a wifi adapter for a Softub that sits between the top unit and temperature probe, and the stock Softub control board.

This is meant to be used with a circuit board which can be ordered here: https://oshpark.com/shared_projects/QC1GjVG6

It is based on the reverse engineering figured out by Monroe Wiliams. See: https://github.com/monroewilliams/softub/blob/master/hardware/reverse-engineering.md

If you are looking for a more plug-and-play solution, check out my replacement firmware: https://steve1066d.github.io/devore.tubs/

It has the following features:

• It provides WiFi support to display or modify temperature.
• It keeps the temperature setting even after a power loss.
• It works with the existing controller board. The safety high temp cutoff is not bypassed, so it continues works for safety.
• It supports increasing the set-points in half degree increments (or whatever is configured) using the up and down buttons.
• Holding down the buttons for over a second will cause the temp change to continue to repeat.
• It can display temps in either Celsius or Farenheight
• It can go to 106F (or whatever max temperature is configured) without any special modes.
• Even on older boards that don't show the current temp, this will still display the current temp.
• It will still display the setting temperature for a few seconds after changing, either through WiFi or the buttons.
• It can optionally display temperatures in tenth of a degrees. (Over 100 degrees would not show the "1", as there are only 3 digits available on the display)
• It can integrate with Home Assistant using MQTT. It appears as a thermostat, and can be controlled with Alexa, if configured.
• It can report button presses back to MQTT. So for instance you could configure Home Assistant to turn off lights if the Softub lights button is pressed.
• It also monitors the temperature inside the pump (actually the CPU temperature which is about 30 degreees F over ambient). This could be used to warn of a cooling coil blockage or failure on the pump.
• If the board shows any error codes (Like IPS), they will be shown instead of the temperature.
• The special modes (like 12 hour or 24 hour modes), still work as expected, as any botton presses besides up and down are passed through to the controller.

It does this by:

• It uses a custom circuit board with a Seed XIAO ESP32S3 that plugs into the controller board where the display and temperature sensor currently plug into.
• The display and temperature sensors plug into the adapter circuit board.
• It uses Adafruit 16 bit ADC and DAC boards to perform high accuracy temperature reads and reporting. (It is probably overkill, as the ESP32 has analog in and out, but the boards weren't very expensive).
• It communicates with both the board and display, and allows the tub to be controlled with both the buttons on the pump and Wifi.
• It emulates pressing the hottub up and down buttons in response to change in the set temperature.
• It adjusts the temperature reported to the stock Softub board as appropriate. So if you set the temp at 102.5, it will keep the board at 102, but decrease the temp sent to the board by 1/2 degree. Or if you select over 104, it decreases the reported temp by the amount over 104. Otherwise it keeps the reported temperature as-is.
• The stock controller continues to maintain the temperature as it always has, but based on the temperature this adapter reports to the board.
• It determines if the pump is on by using the filter and heat lights, in additon to recent filter button presses. It also listens for mqtt messages power_on and power_off, which I've configured in home assistant to return if the power usage indicates that the pump is on.

Work left to do:

• I haven't done much testing on the boards that show "P" when up to temp. If there is an issue, it can be worked around by jumpering JP3 on the Softub board. This will make it work like the older boards. Removing the jumper returns to the normal behavior.
• Allow temporarily turning off the pump by pressing the Jets button even when it is calling for heat. This might be able to be done by temporarily raising the reported temperature.
• The temperature probe on a hot tub isn't in the best location, so its hard to use the probe to come up with the actual temperature. The stock controller seems to turn on when it was 2 degrees below the set point and off when it reached the set point. But because the probe is in the pump and not in the tub, it doesn't really reflect the real temperatures. Once I get more data I'm hoping to more accurately estimate the temperature. For now it just reports the temp of the probe.
• Provide an accurate estimate of the pool temp even when the pool is off. I'd like to avoid having to show the "P", and instead just always show the temperature.

Possible Improvements

• Create a version of the PCB and software that replaces the stock controller board. Ideally it would have the same tabs and connections so it would be a simple replacement, not requiring any soldering or new crimping. My thoughts is to provide a safety cut-off in hardware to shut the tub off with a simple circuit, so the safety of the original design remains.
• Add the 12hr mode and economy modes that were added with the post 2011 controller boards.
• Allow replacing the existing temperature probes with other easier to obtain probes. For example, using $10 1-wire digital probe could work just as well as the expensive replacement official probes. This could be done with just a firmware change.
• Add the ability to use different top units, such as a much cheaper Balboa display.