Sniffed Transformer Puts Wired Doorbell Online

August 6, 2019 by Tom Nardi 30 Comments

There’s certainly no shortage of “smart” gadgets out there that will provide you with a notification, or even a live audiovisual stream, whenever somebody is at your door. But as we’ve seen countless times before, not everyone is thrilled with the terms that most of these products operate under. Getting a notification on your phone when the pizza guy shows up shouldn’t require an email address, credit card number, or DNA sample.

For [Nick Touran], half the work was already done. There was already a traditional wired doorbell in his home, he just had to come up with a minimally invasive way to link it with Home Assistant. He reasoned that he could tap into the low-voltage side of the doorbell transformer and watch for the telltale fluctuations that would indicate the bell was doing its thing. The ESP8266 has an ADC to measure voltage and WiFi to connect to Home Assistant, so it seemed like the perfect bridge between old and new.

Of course, as with any worthwhile project, it ended up being a bit more complicated. Wired doorbells generally operate on 16-24 VAC, and [Nick] knew if he tried to put his Wemos D1 across the line he’d release the critical Magic Smoke. What he needed was a voltage divider circuit that would take low-voltage AC and drop it to an even lower DC voltage that the microcontroller could cope with.

The simple circuit [Nick] comes up with cuts the voltage way down and removes the negative component completely. So what was originally 18.75 VAC turned into a series of 60 Hz blips at 2.4 VDC; perfect for feeding into a microcontroller ADC. With a baseline to work from, he could then write some code that would watch for variations in this signal to determine when the bell was ringing.

Or at least, that was the idea. While the setup worked well enough on the bench, its performance in the real-world left something to be desired. If his house guest had a heavy hand, it worked great. But a quick tap of the doorbell button would tend to go undetected. After investigating the issue, [Nick] found that he needed to use some software trickery to ensure the ESP8266 was able to keep up with the speedy signal. Once he was able to reliably detect short and long button presses, the rest was just a simple matter of sending an MQTT message to his automation system.

Compared to the hoops we’ve seen other hackers have to jump through to smarten up their doorbells, we think [Nick] got off fairly easy. This project is also an excellent example of how learning about circuit design and passive components can still come in handy in the Arduino Era.

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A Farewell To YouTube Sub Counters Set To Break With API Change

August 1, 2019 by Dan Maloney 22 Comments

Of all the things you never would have guessed you’d need just ten years ago, a YouTube subscriber counter would probably rank highly. You would have guessed that the little hits of dopamine accompanying each tick upward of a number would be so addictive?

As it turns out, lots of people wanted to keep a running total of their online fans, and a bewilderingly varied ecosystem of subscriber counters has cropped up. All of them rely on the API that YouTube exposes for such purposes, which as [Brian Lough] points out is about to change and break every subscription counter ever made. In the YouTube sub counter space, [Brian] is both an enabler – he built an Arduino wrapper to fetch YT sub counts easily – and a serial builder of displays for other YouTubers. The video below shows a collection of his work, many based on RGB LED matrix display, like the one used in his Tetris-themed sub counter. They’re all well-built, nice to look at, and sadly, destined for obsolescence sometime in August when the API changes.

The details of the API changes were made public in April, and for the subs count it amounts to rounding the count and displaying large counts as, for instance, 510k as opposed to 510,023. We’re confident that [Brian] and other display builders will be able to salvage some of their counters with code changes, but others will probably require hardware changes. Thanks, YouTube.

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Four Years Of Learning ESP8266 Development Went Into This Guide

July 30, 2019 by Bryan Cockfield 20 Comments

The ESP8266 is a great processor for a lot of projects needing a small microcontroller and Wi-Fi, all for a reasonable price and in some pretty small form factors. [Simon] used one to build a garage door opener. This project isn’t really about his garage door opener based on a cheap WiFi-enabled chip, though. It’s about the four year process he went through to learn how to develop on these chips, and luckily he wrote a guide that anyone can use so that we don’t make the same mistakes he did.

The guide starts by suggesting which specific products are the easiest to use, and then moves on to some “best practices” for using these devices (with which we can’t argue much), before going through some example code. The most valuable parts of this guide especially for anyone starting out with these chips are the section which details how to get the web server up and running, and the best practices for developing HTML code for the tiny device (hint: develop somewhere else).

[Simon] also makes extensive use of the Chrome developers tools when building the HTML for the ESP. This is a handy trick even outside of ESP8266 development which might be useful for other tasks as well. Even though most of the guide won’t be new to anyone with experience with these boards, there are a few gems within it like this one that might help in other unrelated projects. It’s a good read and goes into a lot of detail about more than just the ESP chips. If you just want to open your garage door, though, you have lots of options.

ESP8266 Sound Machine Soothes Baby Remotely

July 28, 2019 by Kristina Panos 7 Comments

[Zack] had trouble getting his six-month-old to sleep through the night. That was before he found out about ‘shh’ videos on YouTube. These are exactly what they sound like: eight hours of someone whooshing white noise into a microphone. He set a phone up on a charger in the nursery and let one of these play overnight. But the phone was unreliable. It would lock up, or just crash completely, making the baby’s distress worse.

To restore peace in the house, he built a sound machine that both simplifies and fortifies the white noise shh-loution. It uses an ESP8266 and a DFPlayer Mini to loop a lone MP3 file of shh-video audio and play it from a small speaker. By integrating the machine with Home Assistant, he’s able to trigger the sound remotely at baby’s bedtime. ESP Home has no module for the DFPlayer, but [Zack] built one that he’s happy to share.

If you are mired in early parenthood, this is a nice, simple solution. The DFPlayer does all the work of reading from the SD card and converting the signal to analog for speaker output, so there’s no need to get your hands dirty wasting valuable sleeping or kid-playing time.

Once the kid starts toddling out of babyhood, [Zack] could turn to ESP8266-based ambient lighting to help establish the difference between sleep and wake time.

Familiar Parts Make Interfacing Weather Station Easy

July 27, 2019 by Lewin Day 12 Comments

Hackers love to measure things, and enjoy monitoring the world around them. Weather stations are a big part of this, and many tinkerers have tried to interface such hardware with varying levels of success. [Ray] is one such individual, and was pleasantly surprised when working on a recent project.

Unlike more old-school models, the model [Ray] found himself working on was a modern unit with a significant number of sensors, a WiFi interface, and even a color screen. Reading the manual, [Ray] noted the device used the IP 192.168.4.1, which is commonly used by the ESP8266 when running in AP mode. The hunch proved to be correct, and opening the device revealed an ESP-WROOM-2 running the show.

Now working with familiar parts, it was simple to hook up to the onboard serial port to scope for data. To [Ray]’s delight, the device was outputting all the weather data out over the connection, and in plaintext to boot. The station also featured the ability to connect to Weather Underground, and watching the debug messages during this process helped [Ray] to understand the format of the information.

It’s rare that manufacturers make it so easy, but debug ports can often be a treasure trove of information to the budding hacker. We’ve seen others cracked before, too.

Tea Bot Solves Another First World Problem

July 24, 2019 by Al Williams 19 Comments

In the movie Wall-E, future humans live in floating chairs and have everything done for them. Today, we grumble if we have to go to physically find a light switch or a remote control. How far away can floating chairs with screens be? T2, the Tea Bot, gets us one step closer to that. Using a laser-cut frame, an ESP8266, and a servo motor, the T2 brews your tea for exactly the right amount of time.

We were kind of hoping the robot would at least dunk the tea bag in and out, but it does provide a web interface that lets you select the brew. Of course, the code is available, so you could make modifications — maybe turn on a hotplate underneath the cup.

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Weather Station Can Rock You Like A Hurricane

July 22, 2019 by Sven Gregori 5 Comments

People love to talk about the weather. It’s the perfect small talk, whether you’re trying to start a conversation or keep one going by avoiding an awkward silence. In the same fashion, weather stations are an ideal starting point for any sort of sensor-related project ideas. You get to familiarizing yourself with communication buses, ADCs, general data acquisition, and you learn a lot in figuring out how to visualize it all.

What if your weather station didn’t visualize anything? [OttoNL] is answering that question with a MIDI-generating Weather Station that uses the mood of the music to convey the condition of the elements outside.

Using an ESP8266 programmed via the Arduino IDE, [OttoNL] hooked up a light dependent resistor, a rain sensor, and the all-round workhorse BME280 for temperature, barometric pressure, and humidity to it. Reading the sensors, the ESP will generate MIDI notes that are sent to a connected synthesizer, with each sensor influencing a different aspect of the generated MIDI signals. A sadder, slow tune will play during rain and a fast upbeat one during sunshine. While it doesn’t use the ESP’s WiFi functionality at all at this point, a future version could easily retrieve some weather forecast data from the internet and add it into the mix as well.

Connect this to your alarm clock, and you can start your day off in the appropriate mood. You can even customize your breakfast toast to really immerse your morning routine in abstract weather cues.

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