Sonoff Wi-Fi Smart Switches

Summary

In this project I want to share my experience with several Sonoff Wi-Fi smart switches from Itead Studio. They send them to me for free (sponsoring).

Devices

I use three Sonoff Wi-Fi smart switches. These are:

• Sonoff Pow
• Sonoff Dual
• Sonoff TH16

For more information about power consumption, case sizes, etc., please visit the manufacturer pages. Copying that information to here doesn't make sense to me and may change in future revisions of the devices.

DUAL

This switch has two mechanical relays which can be connected with several actuators like lamps, etc.

I use this device with a connected socket and power connector to use it for regular devices without the need to modify them.

POW

This device has one relay but is able to measure the actual power consumption. I use this device for my TV, for example, to turn it on and off and measure the power consumption.

TH16

This device has one relay and a connection for an DHT22 (AOSONG) based temperature/humidity sensor. The device is able to report the measured temperature to the app and the one relay can be used as a regular relay to control a connected device. The app provides several special features for temperature-controlled actions.

All devices

All devices have no ability to set the brightness of lamps, etc. The state is either "On" or "Off".

App

There is an iOS app available at the Apple App Store which allows controlling the devices. I personally use an iPhone 7, so my experience here only covers the iOS version of the app. The name of the app is "EWeLink".

Pairing

All devices are regular Wi-Fi clients (supporting WPA2) which are attached to my regular 4.8GhZ Wi-Fi network. The pairing process is fairly easy and there is a Wizard which guides through the required steps. After the pairing was done, I uploaded several firmware updates for the devices.

Turning a device on or off

The most important feature of the app is to use it as a "remote" for the devices. After the app is started every device is shown in a device list with status information (on or off). It is also possible to toggle the device status within that overview. It is not required to jump into device details.

A detailed view is also available for each device which shows additional information like the actual power consumption for the POW version of the devices.

Scenes

Instead of turning on every device, it is also possible to define a scene and apply a bunch of states.

Cloud Access

It is possible to control each device while travelling because the Wi-Fi devices are connecting with a cloud service. This allows checking temperature for example from nearly everywhere. Even with this round-trip from my home to a cloud server the latency is very slow (below one second).

Timer

The app provides several features like a timer which allows turning the device on or off at a certain day of week at a defined time. It is also possible to activate a countdown to turn off a device after a certain amount of time.

Visual power consumption graph

The app shows a visual graph for devices which are supporting measurement of power consumption.

Pro

• No expensive infrastructure like KNX is required.
• Pairing process is very easy (but fails some times).
• Cheap in comparison with other technologies.
• It is possible to access the devices from the internet.
• The app provides useful features out of the box like Timer, Power Consumption Graph and Countdown.
• Devices can be shared with other family members. So everyone has their "own" devices in the app and the shared ones.

Con

• The devices are large. It is difficult to hide them in cases of lamps or behind furniture.
• There is no official API available which can be accessed to build own apps or services.
• Integration in Apple Home Kit is not supported.
• No dimming supported.