Tag Archives: espurna


Useful notifications from your home appliances using Node-RED

Some time ago I worked on a home project to get a notification when my washing machine had done its job based on monitoring its power consumption. There was a good reason for that, the machine was outside the house and I had already forgotten about the laundry several times. And when that happens your only option is to wash it again, because it really smells musty…

Monitoring your appliances

Use ESPurna 🙂

OK, there are different ways to get the info about power consumption. But since we want to be able to process the data ourselves most commercial products won’t be suitable unless we modify it.

Alternatively, those that use radio communication to send data from the meter to the base station might be suitable for a man-in-the-middle hack. For instance, if you own an Efergy power meter you must know you can sniff the data it sends using a simple RTL-SDR dongle.

But for most cases, your best chance is to get your hands on a commercial product with an ESP8266 chip in it and change the firmware to suit your needs. You can write your own or use an existing firmware like ESPurna, that already supports a bunch of power metering smart switches.

What info do you need?

The idea is to report (via MQTT) power data from each individual appliance very minute. You can then use Node-RED along with InfluxDB and Grafana (or Graphite) to receive, persist and graph your data like in the image below.


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Sonoff S31, a world apart

It’s not that other Sonoff products are not “serious” business, but there are a number of design changes in the Sonoff S31 that make this new product a world apart. For the functional point of view it looks like a S20 with POW-powers, but they have redesigned the product completely. The result is very very interesting.

  • Revamped case, more compact and sturdy
  • Redesigned PCB, actually 2 different PCBs for main and control
  • Different power monitor chip: the CSE7766 (same as in the new POW R2) replaces the HLW8012

The only drawback: it’s only compatible with plug types A & B, tat is central and north-america and few other countries. I’d love to see a S31-EU schuko version!

You can buy the S31 from Itead (see link above) or via the usual marketplaces. Actually the S31 is slightly cheaper [Ebay] on some of them.

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Yet another WiFi light bulb

Eight months ago I reviewed and hacked the AiLight WiFi light bulb by AiThinker. By the time there was a number of people doing the same because of a key reason: it sports an ESP8266 microcontroller and it is based on the OpenLight by Noduino, that had already provided open source code for the LED driver inside, the MY9291.

Let time pass and I was doing the same with the Sonoff B1 light bulb by Itead Studio. That was two months ago and the conclusion was that the AiLight is brighter the the B1 but the lacks warm white channel the Sonoff bulb has.

And now here I have yet another WiFi light bulb, the Arilux E27 Smart Bulb. It looks pretty much like the other two, same shape, same microcontroller, same driver, but different base again and most important: different LEDs. So how does this one compare to the other ones?

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Sonoff B1, lights and shades

Six months ago I was reviewing the AiThinker AiLight, a great looking light bulb with an embedded ESP8266EX microcontroller, driven by a MY9291 LED driver. Just before summer IteadStudio released it’s Sonoff B1 [Itead.cc] light bulb, heavily inspired (probably same manufacturer) by the AiLight, at least on the design.

Now that IteadStudio has become popular between the home automation community you can also find the Sonoff B1 on global marketplaces like Ebay or Aliexpress for around 13€.

A closer look at the B1 uncovers some important differences. But before going deeper into the details let me first say that this post will probably look more like a review, at least more than I use to write. And second, yes: ESPurna supports the Sonoff B1 🙂

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Connected power meter

A few weeks ago a user came with a request to add support in ESPurna to a power meter that had been hacked by Karl Hagström. It is a very cheap chinese power meter with plenty of room on the inside, enough to house an ESP8266 module and a DC/DC power supply and the main IC protocol had been reverse engeneered. There even was a repository by the Harringay Maker Space with sample code for an arduino compatible platform.

I found it really interesting so I jumped in and ordered two of them (for 25,20 euros in total). Unfortunately the seller I bought it from has ran out of them. But you can still find them on the usual market places, like these ones [Ebay] or (also with non-EU variants) these ones [Aliexpress].

When I received them I quicky unscrewed the enclosure of one of them and… wow, it looked slightly different than that on Karl’s post but also different from the one the people at Harringay Maker Space had worked with.

p1240281s p1240279s

I went back and forth and I noticed the hack was almost 2 years old and the board was clearly different: different version (unlabelled on Karl’s pictures, version 2014-04-28 on Harringay’s power meter and 2016-12-18 on mine), different board layout with a different connector between the power meter board and the display (7 wires on theirs, 6 on mine). But the most important difference was the main power meter IC. Karl had reverse engineered the ECH1560 on his power meter, a 24pin SOP package (on the back on his device, on the front in Herringay’s power meter). Mine was only 16pin…

p1240274sI had to decipher the IC mark using parts from both devices since the manufacturer had crossed out the marks (they don’t want us to hack it or what?). Finally my best guess was V9261F. I quicky googled it and… bingo!

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