Add support for the M5Stack 4-Relay I²C?

[Jeltel]

Thanks for this :) Haven't connected it to my heatpump yet, but it looks very promising

I've used a 4 channel relay with the old ESP Altherma to switch Smartgrid, Heating and Cooling. This does not work with specific pins, but with some communication protocol to the 4 channel relay. I've added this function to a local version of ESP Altherma V2. With the relais there is a selection box to select the 4 channel relay.

There is also a option to set a cooling pin if the 4 channel relay is not used.

Is that a usefull addition to ESP-AlthermV2?

Yes I've used Claude to help me add the 4 channel relay and cooling pin

AI summary of what has been changed in my local version:

Add M5Stack 4-Relay Support

Summary

Add support for the M5Stack 4-Relay I²C unit so ESPAltherma can control heating, cooling, and Smart Grid outputs through one relay module. Existing GPIO-based relay configuration remains available.

Changes

• Add a driver for the M5Stack 4-Relay unit and initialize it over I²C using GPIO 32 (SDA) and GPIO 33 (SCL).
• Map relay outputs to heating, Smart Grid 1, Smart Grid 2, and cooling.
• Add a relay-type setting to the web interface. Persist the selected relay type and relay configuration in the application config.
• Keep the existing GPIO relay controls available when the 4-Relay unit is not selected. Initialize GPIO relay outputs to their inactive state.
• Add separate, mutually exclusive heating and cooling switches for Home Assistant.
• Probe the I²C relay unit periodically and report connection changes in the Events feed and through a retained Home Assistant diagnostic sensor.
• On reconnect, restore the last applied Smart Grid state and turn the heating and cooling outputs off.
• Update MQTT discovery and topics for the new switches and relay connection sensor.
• Update the web interface translations for German, Spanish, French, Italian, and Dutch.
• Update topic tests and the README, control, Home Assistant, and upgrade documentation. Add an implementation summary for the 4-Relay integration.

[raomin]

Thanks for this @Jeltel. I'm not sure of the need for the community though.
The v2 allows for fine tuned power control, dhw and leaving water target. So, to me, you only need one relay (thermostat) and you can control everything else via X10A. Happy to discuss this with others...

[Jeltel]

Maybe I don't understand completely how this works

The smartgrid function can be replaced with power control indeed. But I already have this relay, so I need the extra protocol in there. And yes that is a me problem :D

But how do you make sure the heatpump is cooling then? The 'thermostat' relay or Heating only tells the heatpump to go for heating right? And then it follows the Heating Curve right? So for cooling, you would need the cooling terminals i'd figure.

[Jeltel]

I've managed to build a powershell script that adds the 4 channel relay to your build

If anyone wants that script I'll be glad to share it