Flip-Dot Oscilloscope Is Flippin’ Awesome

November 9, 2021 by Adam Zeloof 6 Comments

Oscilloscope displays have come a long way since the round phosphor-coated CRTs that adorned laboratories of old. Most modern scopes ship with huge, high-definition touch screens that, while beautiful, certainly lack a bit of the character that classic scopes brought to the bench. It’s a good thing that hackers like [bitluni] are around to help remedy this. His contribution takes the form of what may be both the world’s coolest and least useful oscilloscope: one with a flip-dot display.

Yup — a flip-dot display, in all it’s clickedy-clacky, 25×16 pixel glory. The scope can’t trigger, its maximum amplitude is only a couple of volts, and its refresh rate is, well, visible, but it looks incredible. The scope is controlled by an ESP32, which reads the analog signal being measured. It then displays the signal via an array of driver ICs, which allow it to update the dots one column at a time by powering the tiny electromagnets that flip over each colored panel.

Even better, [bitluni] live-streamed the entire build. That’s right, if you want to watch approximately 30 hours of video covering everything from first actuating a pixel on the display to designing and assembling a PCB to drive it, then you’re in luck. For the rest of us, he was kind enough to make a much shorter summary video you can watch below. Of course, this scope doesn’t run Doom like some others, but its probably only a matter of time.

Thank to [Zane Atkins] for the tip!

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Halloween Hack Requires Minimum Code, Produces Maximum Fun

November 7, 2021 by Adam Zeloof 11 Comments

Every year, [Conor O’Neill] hacks something together to spook and entertain trick-or-treaters who happen by his home on Halloween. He’s noticed a pattern — every year the project involves a mess of code, often slapped together using different frameworks and languages. Attempting to alleviate that, and maybe make things a bit more friendly to beginners who understandably find code-intensive project daunting, this year he set out to write as little code as possible.

Rather than take the electronics-only route, which would undoubtedly include a few 555 timers and some other classics, [Conor] elected to stick with higher-level embedded boards, including fan-favorites such as an ESP32 and a Raspberry Pi, while still trying to keep code to a minimum. Thanks to the visual languages Espruino Blockly and NODE-RED, he only needed to write a couple lines of “traditional code,” as he calls it: a simple JavaScript HTTP request. The project itself consisted of an ultrasonic sensor hooked up to an ESP32, which would detect when children approached the door. The ESP32 used Espruino visual scripting to notify a Raspberry Pi when it sensed motion. The Raspberry Pi would play some spooky sounds, and coordinate with some old conference badges to turn on some lights and trigger a fog machine. The Pi also used a service called Tines to send a door notification via Telegram.

Okay, so this is still by no means simple, but it is interesting how much can be done without writing much code (and the end result was great!). [Conor] says he’s been building similar Halloween projects every year for the last ten or so, and it shows — we wrote about another one of his haunted doorbells back in 2015. We’re looking forward to seeing what he cooks up next year, and we hope you’ll have some awesome automated Halloween decorations as well!

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Photo of an automated plant watering system attached to four potted plants.

Automation Allows You To Leaf Your Plants Alone

November 5, 2021 by Stephen Ogier 11 Comments

The greatest threat to a potted plant stems from its owner’s forgetfulness, but [Sasa Karanovic] has created an automation system that will keep his plants from getting too thirsty. Over the past year [Sasa] has been documenting an elegant system for monitoring and watering plants which has now blossomed into a fully automated solution.

If you haven’t seen the earlier stages of the project, they’re definitely worth checking out. The short version is that [Sasa] has developed a watering system that uses I²C to communicate with soil moisture, temperature, and light sensors as well as to control solenoids that allow for individual plants to be watered as needed. An ESP32 serves as a bridge, allowing for the sensors to be read and the water to be dispensed via an HTTP interface.

In this final part, [Sasa] integrates his watering system into a home automation system. He uses a MySQL database to store logs of sensor data and watering activity, and n8n to automate measurement and watering. If something isn’t quite right, the system will even send him a Telegram notification that something is amiss.

If you think automation might be the best way to save your plants from a slow death, [Sasa] has kindly shared his excellent work on GitHub. Even if you don’t have a green thumb, this is still a great example of how to develop a home automation solution from scratch. If you’re more interested in television than gardening, check out [Sasa]’s approach to replacing a remote control with a web interface!

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ESP32 Internet Radio Is No Game

October 30, 2021 by Al Williams 6 Comments

More than once, we’ve looked at a cool board like the TTGO T-Display and thought, “What can we build with this?” If you’re [Danko Bertović], the answer is the tiny Internet radio you can see in the Volos Projects video below.

Of course, the core Internet streaming code would be useful with any ESP32, but the display makes for a good-looking unit. The code is available on GitHub. With judicious use of network and audio libraries, the player only takes a few hundred lines of code. Pretty impressive considering it even shows a visualization on the tiny display screen.

What we’d really like to see is a nice case, power supply, and speaker option to make a tiny and portable unit. With a 3D printer, it is easy to make very professional-looking projects, as we often see. On the other hand, it does look better than the breadboard version you can see towards the end of the video. It is, though, a neatly done breadboard.

If you want a larger screen, you might enjoy the ESP32 internet radio we looked at before. Probably our favorite case for an Internet radio was this globe.

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An animated newspaper image from Harry Potter

Muggle Uses E-Paper For Daily Prophet Replica

October 29, 2021 by Chris Wilkinson 12 Comments

News from the wizarding world is a little hard to come by for common muggles, but [Deep Tronix] has brought us one step closer to our magical counterparts with their electronic replica of the Daily Prophet newspaper.

Those familiar with the Harry Potter series will no doubt be familiar with the Daily Prophet. In the films, the newspaper is especially eye-catching with its spooky animated images, a reflection of the magic present throughout the wizarding world. This was achieved with post-production special effects for the films, but this fan-made front page of the Prophet brings the concept to life using e-paper technology and a few other interesting gadgets, all hidden away in a picture frame.

As mentioned, the heart of this project is the e-paper display and a Teensy microcontroller. While e-paper displays are excellent for displaying static text and simple graphics, they are usually not suitable for moving images due to suffering from a form of ‘burn in’, which can leave errant pixels on the screen. This means that e-paper technology typically has a relatively low frame rate for video. [Deep Tronix] has used a custom dithering library to somewhat mitigate this issue, and the results are impressive. Moving images are loaded from an external SD card, processed, and then displayed on the e-paper display, which is almost indistinguishable from the newspaper print that surrounds it.

The seemingly magical newspaper also has a face detection feature, which is enabled by a hidden camera and the venerable ESP32 microcontroller. This system integrates with the Teensy to record and then display the reader’s face on the e-paper display. A neat trick, which is made all the more eerie when these faces are later displayed at random.

We’ve seen Daily Prophet replicas before using more traditional display technology, however the move to an e-paper display goes a long way to improving the overall aesthetics, despite the lower frame rates. With Halloween just around the corner, you might just end up tricking a few people with this clever prop – check out all the build details here.

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Soil Sensor Shows Flip-Dots Aren’t Just For Signs

October 28, 2021 by Donald Papp 13 Comments

Soil sensors are handy things, but while sensing moisture is what they do, how they handle that data is what makes them useful. Ensuring usefulness is what led [Maakbaas] to design and create an ESP32-based soil moisture sensor with wireless connectivity, deep sleep, data logging, and the ability to indicate that the host plant needs watering both visually, and with a push notification to a mobile phone.

A small flip-dot indicator makes a nifty one-dot display that requires no power when idle.

The visual notification part is pretty nifty, because [Maakbaas] uses a small flip-dot indicator made by Alfa-Zeta. This electromechanical indicator works by using two small coils to flip a colored disk between red or green. It uses no power when idle, which is a useful feature for a device that spends most of its time in a power-saving deep sleep. When all is well the indicator is green, but when the plant needs water, the indicator flips to red.

The sensor itself wakes itself up once per hour to take a sensor measurement, which it then stores in a local buffer for uploading to a database every 24 measurements. This reduces the number of times the device needs to power up and connect via WiFi, but if the sensor ever determines that the plant requires water, that gets handled immediately.

The sensor looks great, and a 3D-printed enclosure helps keep it clean while giving the device a bit of personality. Interested in rolling your own sensor? The project also has a page on Hackaday.io and we’ve previously covered in-depth details about how these devices work. Whether you are designing your own solution or using existing hardware, just remember to stay away from cheap probes that aren’t worth their weight in potting soil.

A tiny bedside clock that's packed with features.

ESP32 Clock Takes Time To Give Weather Info, Too

October 27, 2021 by Kristina Panos 9 Comments

It’s fall in the northern hemisphere, so [Mike Rankin]’s kids are back in school and have returned to consulting him every morning about the weather and what they should wear. Since he’s no meteorologist, [Mike] built a beautifully dim and diminutive clock that does all the work for him, plus much more. It glows a lovely dark orange that’s perfect for the nightstand and those early morning interrogations.

In default mode, this clock displays the time, CO2 level, room temperature, and humidity in that eye-friendly orange. But wave your hand in front of the time of flight sensor, and it goes external, displaying the low and high temperatures for the day, plus the weather conditions forecast. After a few seconds of that, it goes back to default mode. The ESP fetches the time from an NTP server, then gets the weather from the OpenWeather API. The indoor weather comes from a combination sensor on the board.

Inside this tiny package is a beautifully-spun board with an ESP32 Pico D4 for a brain. In addition to the climate sensors there is a combination CO2/TVOC sensor (that’s total volatile organic compounds) to sniff out danger. There is also a pair of push buttons on the back and an ambient light sensor, but [Mike] isn’t using those just yet. Add in the Qwiic connector for future doo-dads, and you have quite the little gadget. Although the pictures make it look kind of big, you can see exactly how small it is in the demo video after the break.