Emmesteel

Library for connecting to Emmesteel Digital Heat Controller. This is the Digital Controller used in the italian-made towel warmers sold by Amba like the modello i, etc

Motivation

They make nice towel warmers for sure, but for a $300 controller the "smart" side of this controller failed to deliver.

No Home Network

The device spins up its own Wifi AP and once connected, it launched a UI to control it using a captive portal. It does not allow you to provide a wifi settings. To make any changes to the device settings or remotely control it, you must always temporarily connec to the device AP.

No Scheduling

They only controls offered are on/off, temperature and a count down shut-off timer. It does not allow scheduling start/end times so you can, for example, turn it own in the morning, and off in the evening.

Solution

This library can communicate and control the device via a short-lived websocket connection. For the Wifi AP problem, it documents how to use RaspberryPi (Pi) as a proxy. The Pi connects to both networks simutaneously, and then proxies home network requests to the device's own dedicated wifi. The Pi proxy also helps solve a very low wifi signal that is caused by the controller being inside a metal junction box.

Finally, a minimal Home Assistant Integration allows to easily remotely control the device, see history and include in any desired home automation.

Network Setup - Summary

1. Setup a RaspberryPi with default OS and connect it to your home wifi
2. Use NetworkManager and a second wifi dongle to connect the pi to the towel warmer SSID (e.g. EMMESTEEL_24TS00112)
3. Use iptables to proxy home network requests to the device on EMMESTEEL_24TS00112

Step-by-step

Network Manager

sudo nmcli connection add type wifi ifname wlan1 con-name EMMESTEEL_<SERIAL> ssid EMMESTEEL_<SERIAL>
sudo nmcli connection modify EMMESTEEL_<SERIAL> wifi-sec.key-mgmt wpa-psk
sudo nmcli connection modify EMMESTEEL_<SERIAL> wifi-sec.psk "<PWD>"
sudo nmcli connection up EMMESTEEL_<SERIAL>

Iptables

Setup Ip Forwarding

sudo sysctl net.ipv4.ip_forward

If not 1 use sudo sysctl -w net.ipv4.ip_forward=1 and uncomment line in /etc/sysctl.conf to make it permanent`

sudo iptables -t nat -A PREROUTING -i wlan0 -p tcp --dport 80 -j DNAT --to-destination 192.168.X.X:80
sudo iptables -t nat -A POSTROUTING -o wlan1 -j MASQUERADE

sudo apt install iptables-persistent
sudo mkdir -p /etc/iptables
sudo iptables-save | sudo tee /etc/iptables/rules.v4
sudo nano /etc/rc.local
sudo iptables-restore < /etc/iptables/rules.v4
sudo chmod +x /etc/rc.local
sudo iptables-save > /etc/iptables/rules.v4
sudo reboot

Verify

1. Laptop can ping pi proxy
2. Pi is connected to EMMESTEEL_ (iwconfig)
3. Pi can curl 192.168.1.1 which is EMMESTEEL_ router ip.
4. Assuming the above is working and iptables routing is correct,
5. curl <pi-ip>/ should return the emmesteel UI.

Take Control

Finally, you can use the home-assistant custom integration to see the status, power on/off, adjust heating level, etc.

Troubleshooting

"Requirements not found: ['websockets==13.1']"

After a HA update, the integration may fail to load with this error because HA bundles its own version of websockets and won't install a conflicting pinned version for custom integrations. The fix is to remove websockets from the requirements list in manifest.json, since pyemmesteel already depends on it and HA's bundled version is compatible.