Tag Archives: ATtiny85

Check the time on an ATtiny 85 ring watch

One ring to rule them all, one ring to tell time!

Watches come in all shapes and sizes, but this DIY ring watch featuring the ATtiny85 is quite a feat of miniaturization! It’s based on two previous posts by Maker Chen Liang, explaining how the watch guts work on a breadboard and how he put a similar design together in a more traditional wrist watch. As he had to use a smaller battery than the breadboard version in his ring, he expects battery life to be around half a year.


The ring’s ATtiny85 was programmed using a Digispark (as outlined here), and the device’s circuit was set up on three tiny boards for physical flexibility. The circuit board sections included one for the chip, another for the display, and another for three tightly-spaced buttons. These buttons were able to share one analog input pin on the tinyAVR MCU by using a clever technique involving resistors across two of the button circuits. The three buttons were wired into an analog input, giving different voltage reading depending on the button pushed. Since the ATtiny85 could differentiate between these readings, only one pin was needed for control.

Side View

The watch band was 3D-printed, and covered with a clear thermoplastic layer. Although impressive by itself, Liang has plans to “research sync time method, GPS, Wi-Fi + Internet, BLE + mobile phone, and more.” Maybe we’ll see this project expand to a variety of rings that can be worn and linked via Bluetooth depending on what is needed in a particular situation. Do we sense a Kickstarter? In the meantime, check out the Maker’s entire build here.


Blast some tunes on this colorful speaker

An RGB LED strip driver adds some colorful effects to this DIY sound system.

A friend of Philip Verbeek, Guus Boonen, has created an totally awesome handmade sound system comprised of a few speakers, an amplifier circuit, a Bluetooth module and a charger module with accu, all housed inside a custom case with a handle on top for portability.


During the build process, Boonen had come up with the idea to also include an RGB LED strip driver, paving the way for some pretty cool effects. This board, which was specially designed by Verbeek, features a rotary encoder and an ATtiny85 at its core. What really makes this driver special, though, is the inclusion of the rotary encoder with an integrated tact switch. This not only makes all kinds of new user interfaces possible, but enables precise control of the LEDs.

A panel in the back allows a user to adjust the light color and brightness, as well as turn the speaker on/off. Aside from that, the system is powered and charged via AC, and is equipped with Bluetooth connectivity and an audio jack.


As Verbeek explains, “The custom driver includes two modes. Mode 1 is where you can set the color. When pressing the tact switch in the rotary encoder, you will go to mode 2 where you can set the brightness level of the RGB LEDs. When holding the tact switch for two seconds, the LEDs will go off in a nice fade animation.”

With every touch of the push button (which is built into the rotary encoder), the variables are saved in the memory. This way, whenever the device is powered on and off again, the driver will revert back to where a user left it. Intrigued? You can check out the entire project here, or see it in action below!

Building a power switch for Chromecast

This Maker built a power switch for his Google Chromecast with the help of an ATtiny85, Bluetooth and Tasker.

The Google Chromecast device is a neat media player that simply plugs into your TV to play media. One thing it doesn’t have, though, is a way to turn it off remotely. This might not be a problem for most people, but Ilias Giechaskel was using it as an input for a computer monitor which didn’t have a “remote off” function. It did, however, have the ability to go to sleep when no input was received, so turning off the Chromecast would serve a useful function in his setup.


Gichaskel decided to accomplish this task with “hardware that he already had available,” and opted for an ATtiny85 with its small physical footprint and number of I/O pins to control everything. He also used a Bluetooth chip for communication with his smartphone. The module receives an “on” or “off” command from the phone, then the ATtiny switches power to the Chromecast appropriately.

Originally, this setup meant that the user had to manually turn Bluetooth on, connect it to the Arduino, send the appropriate commands, then turn Bluetooth off. Doing all of this manually wasn’t what Giechaskel had in mind, so he wrote a Tasker plugin which takes care of this for him.


Of course, this isn’t Giechaskel’s only ATtiny85 hack. Be sure to check out how he replaced the guts of a bathroom scale using one!

ATtiny85 helps breathe new life into a broken scale

Rather than toss out a broken bathroom scale, this father-son duo decided to refurbish it with an all-new electrical system.

What do you do when your scale breaks? If you’re like most people, you either buy a new one, or don’t weigh yourself hoping that you didn’t actually gain any weight over the holidays. If, however, you are Oxford doctoral student Ilias Giechaskiel, you simply design a new electrical system for it, then build it with the help of your dad.


As the Maker puts it, “The obvious solution…was to get rid of the internal components, reuse the case and the sensors, and build everything from scratch.”

One of the more interesting techniques employed in this project is the use of a Wheatstone bridge in conjunction with a load cell to measure weight. As the voltage change in this type of setup is quite small, a separate chip was needed to amplify the signal before it was passed to an ATtiny85’s analog input. Another neat design choice was the use of the ATtiny85 with its limited input/output (IO) capability (5 IO pins plus a reset pin).


Giechaskiel explains his selection of MCU,“I like its small form-factor, and did not want to have unused pins.” However, he does admit that more I/O would have been useful to implement more functionality in the scale.

If that wasn’t enough, he programmed the ATtiny with an Arduino, as outlined in these instructions, and his new display is a nice bright red. This would seem to be an improvement over the boring gray, though if you’re not happy with the reading, it might be harder to conceal!


There are several neat concepts in this build, so be sure to check out his code, library, and schematics on GitHub. if you think you might be able to use some of these ideas!



These string racing robots are awesome

One Maker decided to build tiny autonomous robots that could go back and forth along some string like a cable car. 

According to Adafruit forums user HarpDude, “Back in the 1980s, my college-aged brother designed a simple motor+battery car that raced along a string between the birch tree and the street-side power pole. For years now, we’ve been improving on the design.” Although this seems like a fun experiment by itself, one major weakness of the design was that it crashed at the end of its run, needing a human to catch it.


Now 30 or so years later, encouraged by his son the ‘Dude decided to get back into electronic design. Proving that no Maker project is never really finished, he decided to start making these racers again. This time though, his goal was to make them autonomous, able to avoid crashing at the end of the string.

HarpDude’s background is in transistor-based logic, but after discovering the Arduino for himself, it seemed like a this type of system would work well in his device. Adafruit’s Trinket, with an ATtiny85 at its core, fit the bill perfectly for his little device, and at around seven bucks, wouldn’t be a tragedy if one did end up crashing.


Currently, his string racer can be used in two modes, “Boomerang,” which travels to the end of the line and comes back, and “Pong,” which goes back and forth continuously. Besides racing, perhaps something like this used with a tiny camera to take neat video footage, or with a slower motor in time-lapse mode.

Ring in the holidays with this cuckoo clock bell

Drive your family cuckoo with this awesome, ATtiny85-powered Christmas bell! 

Last summer, Philip Verbeek visited Philadelphia. And what would a trip to the City of Brotherly Love be without a stop at the Liberty Bell? While there, he bought his own little replica as a souvenir, which he planned to throw on his Christmas tree this year.


However, being the Maker that he is, Verbeek felt that wasn’t enough. Instead, he wanted to take it one step further by having it ring automatically. To accomplish this, he used a servo motor with a small hammer at the end. An ATtiny85 in combination with an RTC mini-breakout board is tasked with ringing the bell.


At the top of every hour, the clock rings the number of the current hour and once at every half hour. (Think of it as a cuckoo clock for your tree.) As an extra feature, Verbeek even included a push button for manual control and an RGB LED on top that illuminates as the bell chimes.

Ready to ring in the holidays? Check out Verbeek’s project here, or watch it in action below!

Starduino is an 8-bit Super Mario tree topper

Bring this classic power-up to life as part of your Christmas decor. 

Super Stars (also referred to as Starmen) can be found in a plethora of Mario Bros. games, including the original and the Mario Kart series. One place you’d typically not find them, however, is on top of a Christmas tree. That was until now.


In the game, when a player gets a star, they become temporarily invulnerable to all damage. This enables them to defeat anything and rack up points, except to hazards that would normally be fatal regardless of power-ups. Well, John Edgar Park has decided to swap out invincibility for some sparkling decor.


The Super Mario fan has built his own 8-bit tree topper using an Arduino, LEDs and a few other off-the-shelf tools. Starduino — a name that was coined by yours truly — is a fairly straightforward project. It consists of an Arduino GEMMA (ATtiny85) that drives an Adafruit NeoPixel ring housed inside a 3D-printed blocky star. Meanwhile, power is supplied by a USB cable plugged either into a wall adapter or a battery.

Still looking for a last-minute focal piece for your tree? Don’t despair! Park has provided a step-by-step breakdown of his build on Adafruit, so you can spark some nostalgia of your own this holiday season.