Little Lifeboat

To control the Combi heater and Heat pump via Home Assistant, I must reverse engineer the communications protocol between the LCD displays and the units. This is more my personal notes.

1. Combi

Arduino like Microcontroller and a LIN bus chip

2. Heat Pump

Tuya board + RS485 (TP8485E), likely running ModBus

The Combi does have a RV-C board available.. for $450, which is insane vs the cost of parts.

The primary issue is that the RV-C documentation is not online, and I’ve yet to hear back from them regarding the documentation. It’s worthless without the documentation and I’m waiting to see if it can be run down.

It’s also goofy that they are going from LIN to RS232 then to RS232 to RVC, which smells like off the shelf components.

Reverse engineering basically looks like probing the data lines then logging when operations are performed on the displays, then working out the schema.

Something like this

I have a oscilloscope coming and a Saleae Logic 8 for decoding. It’ll likely end up being a cold winter project. Bringing these into Home Assistant opens lots of automation logic! I just hope the Ecoflow doesn’t end up being a giant pain.

It’s also possible to hack the tuya firmware on the display itself as it is already running an esp32 like microcontroller, would just need to dump the current firmware, I think, to figure out the control scheme.