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.

Reducing the bill of materials of my Hardware Watchdog timer

One nuance of the first few iterations of any new design is that rarely comes optimized in every important aspect from scratch.

It is very difficult to cover everything, when we are creating something new from the ground up. The creation process is by itself a very good sink of our cognitive energy and focus, leaving little room for a more pedantic mode of thought.

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:

Attempting to repair a Vorwerk TM31 Bimby / Thermomix

At the beginning, when in my house we decided to purchase this kitchen food processor/blender almost 10 years ago, I considered it to be somewhat of an overpriced consumer asset in spite of the multiple features that it enclosed. Still I went with the hype and gave some credit to how much it could make life easier, in particular when it came to cooking meals and otherwise more complicated recipes.

Configuring Home Assistant to run off of a USB drive in a incompatible Raspberry Pi

 A problem with the earlier generations of Raspberry Pi's, especially the Pi 1 and the Pi 2 up to version 1.1, is that these cannot be configured to boot from an external USB storage device.

This is a particular relevant limitation for a number of reasons, including the fact that relying on an SD card for most of the storage needs is a solution that may have limited endurance.

The later versions of the Raspberry Pi (RPi 2 v1.2 and upwards), already offer some form of allowing external USB media to boot the operating system. 

Improving an RPI 2 based Home Assistant server for reliability and performance

For some time I have been using the same Raspberry Pi 2 v1.1 as the infrastructure for my Hass.io instance. It proved to perform quite reliably over the approximately 18 months I have been using it 24x7. From that time during approximately 1 year I used the same SanDisk Ultra XC I 64 GB MicroSD card:

Just for precaution I have later switched to a similar card, a SanDisk Ultra HC I 32 GB, and moved my Hass.io installation onto it:

Building a hardware watchdog timer for a kiosk or other system that needs to run 24x7 - version 2.0

My previous post covered a first version of a watchdog timer that I used in the past for another project. 

You may check it here.

As I mentioned there, I suspected that a somewhat different design would be necessary, because the target device could not have either GPIO pins available for allowing a keep-alive signal to be sent to the watchdog timer, or even if it had, it would be unlikely that the underlying linux OS on the Android system could not have the necessary drivers or support for changing the output of such pins.

Building a hardware watchdog timer for a kiosk or other system that needs to run 24x7

It was proven by Alan Turing back in 1936 that the halting problem applies for computing in general, and our contemporary computing machines are no exception.

Would predicting the crashing of an algorithm or program be a possible function, and we would be able to know the edge cases that cause an application to fail or enter a loop, without having to explore the actual scenarios to find these edge cases. To put it simply we would only have to ask the algorithm in which conditions it would enter a loop or end unexpectedly, and by not providing these inputs we would with absolute certainty not enter these scenarios.

Building a kiosk for Home Assistant from scrap parts - Part 2

With a project of this type, the hardware preparation is just the tip of the iceberg. It was thoroughly explained in the last post, despite one last change still being pending. What lacks is basically the addition of a resistive touch panel to the front of the screen, in order not to depend on the mouse as a pointer/input device. The panel is still somewhere between China and my location..

The first aspect that I found important to cover, now that I had this Android based kiosk up and running, was the ability to remote control it and launch arbitrary applications and services on startup.

Building a kiosk for Home Assistant from scrap parts

It is great to have automation in the house providing increments of comfort such as eliminating manual tasks like cleaning the floor, or to aid in managing the energy consumption by turning off lights and appliances which are not in use, or in the safety side, by providing intrusion detection or monitoring the presence of gas leaks or other hazards, and executing the adequate actions.

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.

Trying to make the most out of Home Assistant + rooted Xiaomi vacuum cleaner + Valetudo

After some time using HA (Hass.io), and even longer using the Xiaomi Roborock (first generation) vacuum cleaner, I kind of felt a certain discomfort in keeping this robot in a stock setup. Sticking to the original firmware meant having a device that is permanently connected to a chinese cloud service, and without the user awareness it sends many megabytes of data daily to this service. Also it meant that integration and features via a platform such as Home Assistant, are limited.

One feature that I fancied for some time was the ability to define zones, and instuct the robot to go to these predefined zones on demand.

Ghost switching can be a bitch if your switch is your main circuit breaker

On my way to eat my own dog food, I learned the hard way that ghost switching is kind of the default problem most people will stumble upon when setting up their MQTT switch for the first time.This is not a big deal when you are configuring a single light switch or some other not so critical appliance. But when your switch is in series with your main circuit breaker, ghost switching suddenly gains a whole different level of importance.

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):