Turning a doorbell switch into a home security camera...and still retain its original function

Today there is an off-the-shelf solution for practically every average-Joe-grade idea one may have. There is always the chance that when one thinks of something that could have a practical purpose and cover a specific need, that there is already a product in the market that will do that function.

Even though home automation may still be in its infancy, today we see a market practically flooded of solutions that one way or another aim to respond in terms of comfort, or to help improve the home experience, or even to enhance the safety and security of its occupants.

Continuing with the Kiosk project

It is fairly interesting that just as with other "things" that I have equipped my house with, this Kiosk and other IoT gadgetry proved to be of relevance not just for my geek person, but for my family as well. For example my wife likes to keep track of the vacuum cleaner progress. Having its map and progress show up automatically when it starts cleaning, proved to be quite useful in this sense:

Tasmota-based multi-channel air quality sensor station

The sense of smell is an amazing function in vertebrate animals. Even the human nose, which is not particularly notable in comparison with other animals, is fascinating in its sensitivity to trace amounts of a large variety of substances. It has a level of selectivity and capability of distinguishing between different kinds of smells, which is very difficult to match by even the most sophisticated artificial sensors.

Having as the main motivation the enrichment of the IoT gadgetry sitting around in my house (and eventually fill up an entire 192.168.1.1/24 network address range), I found that (after the motion and entrance detection device), an interesting device to invest time on would be something capable of sensing multiple air quality parameters at the same time.

ZMAi-90 (or SMTONOFF WDS688) DIN rail meter/switch - more details on GPIOs and configuration

As an update to the previous post where I have shared the details on how to "Tasmotize" this device, I am adding more detail on what is the physical assignement of GPIO pins from the ESP8266, to other components in this device.

Given the pins from the ESP8266 microcontroller that are exposed in its breakout board (which in turn is SMD soldered to the main PCB):

Intrusion / motion / door opening detector using a NodeMCU, some sensors, and Tasmota

The Espressif Systems chip manufacturer kind of created a revolution by opening the door to the creation of dirt cheap chips for building IoT devices. Its low cost led to introduction in the market, of many types of home automation devices, such as switches, light dimmers, smart bulbs, HVAC systems and what not.

On par with that, the open source community quickly became an interested party as well, and this led to the introduction of tools for quickly allowing developers to write interesting applications for practically anything based on these chips. It is the case of the Arduino core for the ESP8266 chip -  https://github.com/esp8266/Arduino. This allowed for Arduino IDE accustomed developers, to write their own code, and either replace the original firmware on commercial devices featuring the ESP8266, or use open-source board designs such as NodeMCU and build their own custom devices.

Reverse engineering the ZMAi-90 DIN rail meter/switch and integrating with Hass.io using Tasmota - Part 2

I finished the first post with  a tone of optimism, in spite of not being quite there yet. But this time I'm bringing the complete story, with something which hopefully can be a useful takeaway for most users.

Initial analysis of the MCU communication

After figuring out what kind of communication was going on between the ESP8266 and the Vangotech V9821 chip (the specialized MCU which does all the metering functions - and a bit more which I will go in detail afterwards), I got a bit puzzled with the output and its consistency. I first connected a known AC current source through the shunt mounted in the relay's output rail, and in the middle of a stream of garbage, some values seemed consistent with the current I was putting and  being shown in the device's display.

I still cracked my mind at trying to figure out a pattern (I felt as if I was trying to incarnate John Nash while looking for patterns in seemingly chaotic data), and trying to prove assumptions such as the last byte being a checksum. But nothing fruitful came out of that first iteration.

Attempting to reverse engineer a home automation oriented smart-meter - Part 1

In my quest to make my house smarter, but still looking forward to keep having control over it, I have been doing some additions which I plan to further document here, in the short term.

In the meantime I thought it would be more relevant to share my findings in regard to a device a bit more "exhotic" than the Sonoff boxes we are all used to. This device is a sort of a miniature smartmeter that fits in a DIN rail next to the circuit breakers.

Just like the Sonoff modules, it also pairs with your WLAN, and connects to a cloud service. Instead of the eWeLink cloud to which Sonoff devices connect to, in this case it connects to another relatively popular cloud service called Tuya.

Waking up devices in Hass.io (Home Assistant)

This is a quick post on a challenge I had to overcome while integrating my SmartTV (an LG TV 55UJ620V) with Hass.io.

I wanted Hass.io to be able to turn on the TV (as such allowing automations to be built on top of it, or for example turning it on through a voice command via Google Assistant). As such I first resorted to using the Home Assistant Wake on LAN built in integration (https://www.home-assistant.io/integrations/wake_on_lan/). It kind of worked, but was not very reliable (perhaps 2 out of 5 times it would work).

I knew that by definition, the way that (Wake-up On LAN) WOL is implemented is inherently unreliable: essentially the target (dormant) device is expecting a frame with a specific pattern of bytes. If it receives that frame, it wakes up the host, otherwise nothing happens. The device will normally scan for that pattern of bytes in the frame regardless of the type of transport level protocol it may be on top of. In the case of WiFi in particular, there is the probability (high or low, depending on the network conditions) of that single frame not reaching the destination. This probability increases with the more hops we have in between.

With this Hass.io implementation I was requiring the magic packet to be sent from a host (the Raspberry Pi where I keep Hass.io running) that is in a separate router vlan, from where the TV is (these are connected via Ethernet and WiFi respectively):

Building a kick-ass home automation by reflashing the Sonoff devices with Tasmota and getting it all working with hass.io

For some time I have been gradually bringing more devices to my house, which are either designed or having features allowing these to be integrated to a home automation system.

In spite of all the concerns that can arise from bringing smart/connected devices to the place where you expect personal privacy to exist, the convenience of having these ends up speaking louder overall..

It all started with having a set of unrelated devices in the house, each featuring connectivity and some cloud-based features provided by the vendor. This is the case for the Xiaomi Rockrobo vacuum cleaner, the Sonoff switches, the multimedia devices such as the TV set (an LG smartTV), and also the Google Chromecast and Assistant devices.

Repurposing an old Android Phone

I had an old Samsung Galaxy Y (GT-S5360) which the previous user didn't particularly enjoy for its performance and replaced with a fancier, newer model. With no obvious use to give to the device, I decided to repurpose it for building some kind of a remote monitoring/observation station, and try to find out how it stands out against the harsh outside environment.

While not attempting to simply put the device outside, directly exposed to the sun, rain and extremes of temperature, I made several customizations to better prepare the smartphone turned into a monitoring station.

The first thing I wanted was to have it entirely self-sustainable. As such I bought a 10 watt photovoltaic panel to harvest the energy required by the device: