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Arduino Projects

4 Posts authored by: Cabe Atwell

Project build Index:

Arduino Project : Three-Finger Ring - Part 1 Getting started and 3D Printing

Arduino Project : Three-Finger Ring - Part 2 Code & the Circuit

Arduino Project : Three-Finger Ring - Part 3 Assemble the Ring!




Step 6: Assemble the ring and install the components.

At this point, disassemble the breadboarded circuit and begin installing it into the ring. Glue and a hobby knife are essentials in this step. Unless you got lucky or have a printer that fabricates with a nigh-zero deviation from mathematical perfection, you will need to use a hobby knife to trim the printed parts.


The power pack is made by sandwiching the batteries together with a positive and negative wire and wrapping the whole affair tightly with electrical tape (Figure 5).


Hot glue was used to fasten the parts in place (Figure 6).


The #4 screws are used as pins for the hinge and to fasten the ring’s lid down (Figure 7).


battery pack.jpg  

Figure 5: The ring battery pack. It is a bit inelegant, but it works.


assembling 1.JPG

Figure 6: Glue the parts into the ring.


screw it together 1.jpg 

Figure 7: The #4 screws fasten the ring together.





Step 7: Power it up and show it off.

You might want to create some fresh images for your ring. Our pics didn’t increase our popularity quite as much as was hoped. Here are a few examples.



element 14 (12).JPG

danger (9).JPG

eulers relation (3).JPG

konami code (12).JPG

i 8 sum pi (8).JPG

max power (4).JPG

nerd life (8).JPG

ohms law (5).JPG

QT pi (6).JPG

stud muffin (28).JPG

final form (9).JPG





Final Notes:

We used a 128x64 OLED screen with that goofy yellow and blue background color. You can use whatever screen you want (almost whatever screen) as long as you adhere to a few guidelines. Make sure that the screen communicates via I2C.


The circuit and code do not use the RESET line. If the screen you get does have a RESET line, pull it HIGH by wiring it to the 5V output on the Trinket Pro.


If the resolution of the screen is anything other than 128x64 pixels, you will have to:

  • Size your images appropriately using a picture editor. You will not be able to use the CPP arrays in the provided code. You will have to create new arrays for your screens exact resolution.
  • You will have to adjust the U8GLIB_SH1106_128X64 u8g(U8G_I2C_OPT_NO_ACK) line in the code so that the U8glib library knows what screen size to work with. There are no provisions in the code or the hardware for detecting any information on the screen, so you have to tell it what is going on.


You are not obligated to use two CR2032 batteries to power your ring. Use a Li-Po battery back, an AAA with a boost converter, whatever. It doesn’t matter. The Trinket Pro can be powered by anything from 5.5-16 volts. If you wanted, there is no reason why a tiny Lithium-polymer battery and a battery management board couldn’t be used in place of the coin cells. Or a solar cell in conjunction with a super-cap or rechargeable battery.


Thanks for reading! Good luck with you own ring project!

Project build Index:

Arduino Project : Three-Finger Ring - Part 1 Getting started and 3D Printing

Arduino Project : Three-Finger Ring - Part 2 Code & the Circuit

Arduino Project : Three-Finger Ring - Part 3 Assemble the Ring!




You have everything ready from Part 1 right? Good. Now it's time to program and get images on that screen.


Step 4: Breadboard the circuit.


Before installing anything, test it on a breadboard. That way, it will be so much easier to troubleshoot. See the electrical schematic in Figure 4.



Figure 3: Breadboard the circuit before installing it.



Figure 4: The electrical schematic for the Screen Ring.



Step 5: Upload the code to the Trinket.


There are a few special considerations for using the Adafruit Trinket. The IDE available from the Arduino site does not natively support it. You will need to either download a special version of the IDE from Adafruit with the board data pre-loaded, or you will have to follow the instructions on the Adafruit website detailing how to load the board data into the IDE. Either way, you will need to start HERE at the Adafruit introduction to the Trinket.


The cornerstone of the Screen Ring code is the U8glib library. It takes care of all the heavy lifting regarding control of the screen. The specifics of this library are well beyond the scope of this article but, if you want to learn more about it, start HERE.



Step 5-2: Create some sweet bitmaps for the ring.

The Arduino code cannot read PNGs or JPGs and the like. It requires BMP images to be converted into data arrays which are then pasted into the code. One of the easiest ways to accomplish this is to use the online image2cpp converter. Just upload a BMP, convert it and then copy the generated code into the Arduino sketch (Figure 5).


There are some rules for getting the converted images to display properly. This can all be done in Windows Paint.

  • Images must be in black and white.
  • Images must be created with a size of 128x64 pixels.


start of Array.JPG

Figure 5: The beginning of an array pasted into the sketch.



Resources: The CODE.


Attached to this post is code used in the Three Finger Ring.


In it, you can change the code to for any images you convert.

Project build Index:

Arduino Project : Three-Finger Ring - Part 1 Getting started and 3D Printing

Arduino Project : Three-Finger Ring - Part 2 Code & the Circuit

Arduino Project : Three-Finger Ring - Part 3 Assemble the Ring!






I already teased this project back on "Geek Day," June 9th 2017. It's now completely finished!


This writeup will go over all the steps taken to build the screen ring. However, you dear reader won’t have to personally execute every step. You have the option of skipping steps because we will provide the 3D models for the ring and the accompanying code. You can procure the parts and print the ring without any of the design work. The one aspect of the design that you may have to change is the size of the holes in the ring to accommodate finger size.


In this section, we are going over all the mechanical aspects of the ring. What parts to gather. And how to get the ring 3D-Printed. (Part 2 is where we will cover the circuit design and code.)


Step 1: Decide on the parts to use.


For the dangerous end of the ring, we used a 128 x 64 pixel 0.96-inch OLED screen, very similar to this screen here. The exact screen we used is permanently blue with a yellow band across the top third. The yellow top third was probably originally intended to display data like the time and the battery charge.

An Adafruit Trinket Pro 5V provided the brains. It has far more IO than is needed but that’s OK. All those extra pins and features can be used on the next version of the Screen Ring.


While the options for powering the ring are many, we went with a couple of CR2032 coin cells. Each coin cell outputs 3V so stacking two of them in series yields a handy 6 volts. This is just enough to power the Trinket and for the Trinket’s onboard MIC5225 to regulate the voltage down to 5V for the OLED screen.


Bill of Materials

Quantity 1 - OLED Display, 128x64, I2C

Quantity 1 - Tactile Switch or something roughly equivalent

Quantity 2 - Adafruit Trinket Pro 5V

Quantity 2 - CR2032 coin cells

Quantity 3 - 10k resistor

Quantity 4 – #4 x 0.5” (12.7mm) machine screws


Step 2: Design the ring.


The ring was designed in SolidWorks, but any 3D CAD software like LIBRECAD or FREECAD will work. Again, you don’t have to design anything if you don’t want to. However, for the those who would attempt it, here is a bit of design advice.

  • It always helps to have at least a nebulous concept in mind.
  • Start by creating 3D models of the parts you know will be used. In this case, the screen, the batteries, the button and the Trinket. The level of detail applied to each of these models is up to you. You may not need to model the Trinket down to the point where all of the components on the board are represented. However, it would be a good idea to at least make the model large enough to fill the immediate space around the Trinket.
  • Start with a box big enough to hold all of these.
  • Position your parts inside the box where you think you would like them.
  • Start removing material where you don’t need it and adding it where necessary. For example, you might add bosses or studs for holding parts.


Once this "box full of parts" was designed, it was obvious that a single finger wasn’t going to be enough support it. For stability and coolness, it was decided that three rings bridged together would do the job. To get the size just right, a few of the ring-only sections were printed up and tested on actual hands.


3D modeling in progress.jpg

Figure 1: 3D modeling in progress. (NOTE: This image is far from the final design)



Step 3: Print the ring.


The 3D models can be sent off to a service like Shapeways or you can print them up yourself if you have access to a printer. For the ring seen here, we used our MakerGear M2. A quick shout out to MakerGear, the M2 deserves all the approbation it gets. It really is a workhorse.


We used this particular blue color (Figure 2) because it’s cool and kind of makes things look like they’re from the future. Oh, and because we had several rolls of that color already on hand.


the printed bits.jpg

Figure 2: This blue color is so rad.



Resources: 3D Models.


Attached to this post is a collection of the 3D models used in the Three Finger Ring.


You could use this as a starting point for your custom design too.


A new Arduino Gameboy called Arduboy. Nostalgia is fun, and nostalgic games are even more fun. Arduboy is a new and cheap ‘gameboy’ that allows you to play games old-school. (via Arduboy)

I can't believe I missed out on this cute little gameboy-ish system powered by Arduino, with a heaping dose of nostalgia along with it. The creator, Kevin Bates, is calling it an Arduboy and he quit his full time job over a year ago to develop this creation. He even moved to China to get the production line all set up and have his product in the making. Now, that is definitely commitment.


The Arduboy is the size of a credit card and has an 8 hour battery life, meaning that waiting for your friend to get out of the bathroom at Starbucks just got way more fun. The Arduboy is powered by Arduino, a black and white 1.3 inch OLED screen, and two piezo speakers. Basically, it has everything you need to game in vintage style.


It also had... a great price point, at $29. You can get one for $39 direct from them. The Kickstarter campaign ended with over $433,000 in funding. This is over 17x their original pledge goal.


arduboy games.JPG

Arduboy games from the community.


The Arduboy is also open source so you can code it to do whatever you’d like. Bates has also sent over 100 developer copies to ensure that there are at least 100 free and open source games available for the Arduboy by the time it gets to you. Some of the games include knock-offs of popular games like Oregon Trail, Flappy Bird, and Ardumon.


Bates told the peeps at Engadget that he eventually wants to sell the Arduboy for $10 and have it available for companies to brand and giveaway as conference swag. If that ever happens, I will attend way more conferences. 

If anything, I take away a little inspiration from the Arduboy. The creator took a simple design all the way, committed to the project, and won out in the end. It's time for everyone to do the same...


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