pyemmesteel 0.0.1

Python Emmesteel Integration

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

Background

No Wifi Config Possible

The uses a dedicated Wifi AP for user-device control but it does not allow you to provide a wifi setting for the device to use. To make any changes to the device settings or remotely control it, you must always temporarily connec to the device AP.

No Scheduling

Furthermore, the software does not allowing scheduling start/end, only a shut-off timer.

Solution

To get around these limitation, I developed a library that can communicate and control the device and a Home Assistant Integration to manage it. For the Wifi AP problem, I decided to use a RaspberryPi as a proxy. The Pi connects to both wifi networks simutaneously, and then proxies home network requests to the device via the device's custome wifi network.

The Pi proxy also helps solve a very low wifi signal that is caused by the controller being inside a metal junction box.

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.