An interesting new Sonoff (ITEAD) product on the way

Browsing through the wiki pages on the ITEAD site is always a good way to pass a few idle minutes and usually rewards the curious reader with interesting stuff (like schematics, for instance) which ITEAD are kind enough to publish for our edification.  Sonoff 433MHz to WiFi bridge, block diagramToday’s snippet was some information on what looks like an as-yet unannounced product, a WiFi to 433MHz gateway module.  The schematic shows this as an ESP8266-based unit, but there’s no separate flash memory chip that I can see and the block diagram refers to an ESP8285 (shame!).  There are both transmitter and receiver sections on the 433MHz side and it appears to use an EFM8BB1 “Busy Bee” 8-bit microcontroller to interface between the 433MHz RX/TX section and the ESP UART, with what looks like a slide switch (S2 on the diagram) to disconnect the Busy Bee to allow for programming of the ESP.  The device itself receives external power via a micro-USB socket.

Depending upon the price (and ITEAD prices are usually pretty reasonable) and the range of the 433MHz components, this could be a neat little device to have around. Front and back views (photo courtesy of ITEAD) It’s not just all of those older 433MHz switch modules that have been available for years, but also the slew of devices which just transmit (doorbells, weather stations, window interlocks, etc).  There does seem to be a four device limit on the number of remote 433MHz modules supported by the stock firmware though, according to the User’s Guide.

Update – ITEAD have just sent out a “Mid-Year Carnival Sale” promotion which features this unit (with the photo above) but, bizarrely for a sale, without a price.

ITEAD Recall

Just in case you haven’t seen it already, ITEAD Studio is recalling some of their Sonoff devices.Sonoff damaged by heat

The recall covers Sonoff TH16 and Sonoff POW units, manufactured during December 2016 and January 2017, which were produced without the correct amount of tinning on the AC power traces required to carry the maximum specified current.

There doesn’t seem to be any easy way to identify affected units though and the recall Sonoff PCB damagenotice seems to infer that only Sonoffs with existing, visible damage will be exchanged.

It’s worth noting that this issue only affects units which are being used with high current loads, so it’s unlikely that you’re going to have problems if you’re only using the modules to switch on your porch lights at dusk.  However, as these units were sold specifically for their higher current handling ability over the original Sonoffs, it is probable that there are many use cases out there which will be affected by this issue.  If you’ve purchased a TH16 or POW unit recently and you’re using it with a load which draws quite a lot of current (any sort of heater, for instance), you should probably stop using it until you can verify with ITEAD Studio whether it is amongst the affected units or not.

ITEAD are asking that people who believe they have an affected TH16 or POW to open a support ticket on their site at:-

How to do a Sonoff memory upgrade

Jonathan Oxer, over at SuperHouseTV, has been running a series of video episodes on the Sonoff product line recently and I really recommend his latest.  The theme of the video is Sonoff-specific hints and hint #1 is how to upgrade the memory chip in a Sonoff.  Jonathan does a great job of demonstrating how to remove the chip with nothing more than “a big, old, clunky soldering iron” and a screwdriver.  A picture is worth a thousand words, so you need to multiply that by whatever the frame rate of a YouTube video is.  Watch it!  It’s worth it.

Another Sonoff Family Member…

…and another Open Source package to run it.

I only recently noticed that ITEAD Studios have added a light switch to their Sonoff line-up.  Sonoff Touch from ITEADThe switch comes in either EU or US single-gang switch-plate sizes and has a glass front panel with a capacitive touch switch.  Inside there’s an ESP8285 module providing remote services via ITEAD’s EweLink cloud application.

There aren’t too many hardware details available on the Sonoff Touch at the moment (what sort of PSU is utilized, or even whether it’s a relay or a triac based device), but people have already started hacking it (no doubt spurred on by a statement in the comments section of the product page that this device “can’t be reprogrammed”).  David Pye seems to be first out of the gate with his (PubSubClient) MQTT implementation; not just identifying GPIO0 as the pin connected to the touch-switch, but also providing short write-ups (with photos) on how to prepare the device for programming, configuration and usage, but also providing bonus “long-touch” and “short-touch” modes in his firmware.

Note that, unsurprisingly, the Sonoff Touch requires that a neutral lead be available in the existing switch box, as well as the switched live lead.  This is something you need to check‡ before ordering a bunch of these (it’s very common for only the live lead to be available).

David’s additional switch handling looks like it might open up quite a few possibilities:-

  • Add an on-time limit for specific lights.
  • Control actual on/off based on time of day.
  • Control on/off by ambient light level (assuming you have MQTT capable sensors).
  • Put unit into OTA mode (ie:- limit reprogramming to those with physical access).
  • Use “long-press” to signal MQTT to switch all controllable lights in room on/off.
  • Additional ten-second press mode for all controllable lights in house on/off.

Seems like you could have tons of fun with this.  Nice one, David!


Hint – Don’t check a bathroom or toilet light switch and assume that all of the other switches in your house will be the same!

Tinkering with the Sonoff TH (by Tinkerman)

Xose Pérez has a great blog ( with lots of hardware projects (as you’d expect from the title).  He’s also heavily into the ESP8266, so it comes as no surprise that he’s already got his hands on the latest offerings from ITead Studio, the Sonoff TH10 and TH16 high power switches.

Annotated board (bottom)Of course, it would be no fun at all if Xose just reviewed the units, but we can trust him to go a lot further than that.  In a recent article, he shows us round the interior of the units (highlighting the differences and the improvements between these new versions and the smaller original) and then demonstrates how to add i2c functionality to the existing sensor socket.  With his small modification, the Sonoff TH goes from being able to interface with either a DS18B20 (One-wire temperature sensor) or AMD2301 (DHT22 style humidity sensor) to being able to handle the whole gamut of i2c enabled input and output devices.

While we’re looking at Xose’s ESP8266 stuff, you might also like to check out his BitBucket repository.  You’ll find an alternative firmware version for the Sonoff series (named “Espurna”), which is probably where the code for the i2c mod will end up, as well as a WiFi manager library (named “JustWifi”), which features automatic AP connection based on signal strength.  There’s a ton of other, interesting stuff in there; some ESP-based and some not.  Definitely a treasure trove.



Weekend Reads [2016/5/28]

Another eclectic electric collection for your delectation.

One of Theo’s more recent updates is to add a couple of photos to the for the Sonoff-MQTT-OTA-Arduino project (scroll down to the bottom of the page) of a (broken) Kaku 433Mhz mains switch which he has gutted and replaced with an ESP8266 to make a Sonoff look-alike.  I can’t find any further details of the project, but from what we can see from the photograph (click to enlarge) and what we already know of the Sonoff, it should be relatively easy to duplicate this if you have any of these older Kaku units gathering dust.

Using “TASMOTA” [Part – 2, MQTT]

[Apologies for those of you have been checking back in regularly for this second article on using Theo Arends’ Sonoff-MQTT-OTA-Arduino package.  Not only has Real Life™ been getting in the way, but I’ve purposely been delaying hitting the big, red “publish” button until I could sort out a nagging little problem I’ve been having (more on that later).  Anyway, here we go with part two…]

In the previous article, we looked at how to access some of the features of TASMOTA (Theo Arends’ Sonoff-MQTT-OTA-Arduino package) using the button/LED and serial-console interfaces.  In this article we’ll take a look at controlling the unit using MQTT.

[…and if you don’t really know what MQTT is, or what it does, Elliot Williams has recently published a clear, easy to read and easy to understand article on Hackaday which is worth looking at…]

The main selling point (other than the extraordinarily low price) of the Sonoff is the fact that it is controllable across the ‘net.  Unfortunately, ITEAD Studios have tied control of the device to their own cloud service which, while it may be great for most people, doesn’t work for those of us who are still using “dumb” phones and who don’t have the option of using a service such as Oogleg’s “voice” to get around that limitation.  Theo’s firmware implements MQTT on the Sonoff which, while it doesn’t help my “dumb” phone, does mean that I can use existing devices on my own network to control it.  I already have a couple of MQTT servers on the local network providing time services to various battery-powered, ESP8266 enabled sensors and collecting data (temperature, humidity, barometric pressure, battery voltage) from them.  It would be a trivial matter to have the internal MQTT servers push that data to one of the free data aggregation services out on the ‘net and only a little more work to make the MQTT interface available through the firewall for external access when we’re away from home (Okay, a lot more work to do it properly 🙂 ).  In my case, the need for MQTT is purely pragmatic; it’s a neat device, but I need MQTT to get it to work without a smart-phone.  For others, there may be a reluctance to entrust data access and control to a cloud service which might disappear at some time in the future.  Whichever it happens to be, Theo’s package “hits the spot” and broadens the possible usage window for the Sonoff (which, long term, is good for ITEAD’s sales, too).

In the previous article we already saw how to set up the “topic” keyword to give your Sonoff devices individual addresses, as well as using “grouptopic” to set a group address to which all devices will listen.  Before you can use MQTT though, you need to configure the MQTT broker (server) details for your network, too.  The recommended way of doing this (unless you have a gazillion MQTT servers on multiple networks) is to simply compile-in the hostname/IP and port number when you initially build the package.  If you’re using Theo’s original package, edit the user configurable details at the top of the sonoff.ino file and change these lines:-

#define MQTT_HOST "sidnas2"
#define MQTT_PORT 1883

…to point to your own MQTT server address and port (if you’re using the version which I put up on GitHub with the function defines added, these settings broken out into user_config.h instead).

You can still change this setting (along with most others) from the serial console, or from MQTT, later on.  Using the serial console (as per the previous examples), you can see that the Sonoff unit automatically reboots after the change:-



ets Jan 8 2013,rst cause:1, boot mode:(3,7)
chksum 0x42

Project sonoff (Topic 2F-toilet-gas-sensor, Fallback DVES_0CB0CB, GroupTopic calling-all-units) Version 1.0.6 (Boot 4, SDK 1.5.1(e67da894))

First we used the “host” command without arguments to interrogate the unit for the current setting. Secondly, we used the “host hazeltonrig…” command to change the compiled-in default. TASMOTA then automatically saves the new value to non-volatile memory and restarts the ESP8266 using the newly updated parameters.

Mosquitto notes

Before we start using MQTT let’s just take a brief look at Mosquitto and the utilities which come bundled with it, mosquitto_sub and mosquitto_pub.  If you’re not using Mosquitto as your MQTT server, feel free to skip this section.

As you’d expect from the names, mosquitto_sub is a command-line utility which allows you to subscribe to a topic, while mosquitto_pub allows you to publish.  They are invaluable tools when setting-up and debugging MQTT installations, allowing you to send arbitrary data and commands and to monitor the output.

You can also install the Mosquitto package on a desktop or laptop machine to make these applications available when you just want to connect to a remote MQTT server on some other machine (both utilities accept a “-h” option with an argument specifying the hostname to connect to and a “-p” option with a numeric argument to specify the port number).  However, typing in the full command names, plus options and arguments can get tedious very quickly, so I’d suggest adding aliases for both commands.  These can be added to your .bashrc (assuming you’re using the common, Bourne Again SHell) to make your life a little easier. Here’s an example (you need to customize it for your specific installation):-

## Aliases for Mosquitto utilities.
## Simple alias for server on this machine.
alias mp=/usr/bin/mosquitto_pub;
alias ms=/usr/bin/mosquitto_sub;
## Aliases for server on remote machine.
## (You can comment-out this whole section if you
## only use the server running on this machine).
alias rmp="mp -h ${MQTT_SRV} -p ${MQTT_PRT}";
alias rms="ms -h ${MQTT_SRV} -p ${MQTT_PRT}";
unset MQTT_SRV MQTT_PRT; ## Prevent pollution.
## End of Mosquitto aliases.

In the .bashrc excerpt above, we are first setting “mp” to be an alias for the full pathname of the mosquitto_pub command and then doing the same for “ms” and mosquitto_sub command.

You only need the second part (from the line “## Aliases for server on remote machine.”) if you are running the MQTT server on a different machine to the one where you’ll be running the mosquitto_pub and  mosquitto_sub commands.  If you do want to use it, you’ll need to change “” (and possibly the 1883 port number) to point to the MQTT server on your network.  The aliases here build on the “mp” and “ms” aliases which we’ve already defined to provide “rmp” (“r”emote “mp”) and “rms” to access our remote server with minimal typing.

The “unset” command simply deletes the MQTT_SRV and MQTT_PRT variables to prevent any unwanted clashes if those names are used by you later.

At the end of that, you can now simplify and shorten your commands.

From:- /usr/bin/mosquitto_sub -h -p 1883 -t stat/#

    To:-    rms -t stat/#


Using the Mosquitto utilities

Now that we have our server defined and some aliases set up, let’s go ahead and dive into using MQTT with the Sonoff and TASMOTA.  I’m going to assume at this point that, if you already have an MQTT broker (server) set up, you basically know how the publish/subscribe model works.  Let’s also assume that our MQTT server (the machine running Mosquitto) is called “hazeltonrig” (as we saw above) and that we’re actually using a laptop to type in these examples and display the output.

Because our laptop is not the MQTT server, we need to use the remote aliases which we set up above to channel all of our publish and subscribe requests through “hazeltonrig”, because for the most part, we are actually interested in interacting with a third machine, the Sonoff module.  So, just the same as with the serial console, let’s start off by getting the status from the device.  The easiest way to do this is to use an MQTT wildcard and listen in on all status broadcasts from all devices on the network:-

rms -t "stat/#"

Going back to our aliases, we can see that this actually expands to the command:-

/usr/bin/mosquitto_sub -h -p 1883 -t "stat/#"

The word “stat” is the top-level topic used by TASMOTA clients to publish their status data.  The “#” is a wildcard, meaning match-anything-from-here onwards.

What happens when you type in this command?  Well, unless your Sonoff happens to be transmitting some status information at the time you hit <CR>, absolutely nothing.  You won’t get a prompt and you won’t see any text on the screen after the command itself.  Not very exciting, but you have just started a subscriber process which will sit there quite happily and spit out any data that comes along with the “stat/” topic header.

If you power-cycle your Sonoff at this point, you  will see a couple of power-up status messages displayed on your screen; something like:-

Sonoff switch

You’ll also notice that, if you still have the serial monitor connected via the USB<->TTL converter, you will start seeing status messages appearing on your screen when you type in virtually any command.  So, if you type “power 1” into the serial monitor, you’ll get output on the serial monitor itself and you’ll also see the word “on” appear in the window where your subscribe command is running (actually, even if you don’t type in commands, the subscribe window will still show messages at power-up, restart or power-down events; for instance, pulling the plug on the Sonoff will produce an “offline” message approximately 10 seconds after the unit is switched off).

You could type a <CTRL>z to put the command into background and carry on typing MQTT commands into the same window where you’ve just started your subscriber process, but that would begin to get a little confusing once that process started to return data, so at this point I’d recommend opening a new window to be able to enter further commands.

Now we need to command the Sonoff to send out some status, so that we can read it with our patiently listening subscriber process.  For this we use our remote publish alias, “rmp”:-

rmp  -t  "cmnd/2f-toilet-gas-sensor/status"  -m  ""

This expands to:-

/usr/bin/mosquitto_pub  -h  -p  1883  -t  "cmnd/2f-toilet-gas-sensor/status"  -m  ""

…which means, publish the command “status” (request status) to the device currently known as “2f-toilet-gas-sensor”.  The -m “” part of the command is simply a null argument to keep mosquitto_pub happy, otherwise it will print a usage summary to try and persuade you that you need to use a message (-m) as an argument to any topic (-t).

The output you’ll see in your subscriber window from the status command with a null (-m “”) option will be something like:-

1.0.6, 2f-toilet-gas-sensor, POWER, 0, 9

This is telling you that the Sonoff is running firmware version 1.0.6, has a topic (addressable name) of “2f-toilet-gas-sensor”, that the last sub-command was “POWER” and the status of the relay is off (“0”). The last “9” indicates the timezone which is currently configured (in this case GMT+9 for Tokyo).

Up Next…

This article has been languishing in the deeper recesses of the WordPress draft cloud for far too long, and has a lot of information for the reader to digest, so I’m going to save some of the other MQTT commands for yet another article and push the big, red “publish” button to get this one out into the wild.

In the next part, we’ll use some of the more useful commands which Theo has provided and look at the difference between normal and group commands.