Rotary Cellphone (Original Project Post)
UPDATE, JANUARY 2021:
Quick history: This project went viral in early 2020. Concurrently,
I was in the process of starting an open source tech company (Sky's
Edge) for robotics, but everyone was asking me to sell the
rotary cell phone. I reluctantly released a kit-version of the project
described on this page, which I maintain for posterity, of which just
over a hundred were sold. Having resigned myself to making
un-smartphones a significant part of Sky's Edge, I concluded early on
that there should be a much more refined, well-thought out version of
the phone that would be easier to build, made from injection molded
parts, operate on the 4G network, and possibly even be something that
I could produce as a ready-made phone. I'm now accepting pre-orders
for this new version (in kit-form), which I intend to start shipping
before summer of 2021. HERE'S
THE LINK. Note that these pre-orders are financing the
production of the phone (like Kickstarter, but without actually using
Kickstarter). Naturally, it's all still open source... I'll publicize
the design data as soon as it's ready to ship.
Originally Posted February 10th, 2020:
Why a rotary cellphone? Because in a finicky, annoying, touchscreen
world of hyperconnected people using phones they have no control over
or understanding of, I wanted something that would be entirely mine,
personal, and absolutely tactile, while also giving me an excuse for
The point isn't to be anachronistic.
It's to show that it's possible to have a perfectly usable phone
that goes as far from having a touchscreen as I can imagine, and
which in some ways may actually be more functional. More
- Real, removable antenna with an SMA connector. Receptions is
excellent, and if I really want to I could always attach a
- When I want a phone I don't have to navigate through menus to get
to the phone "application". That's bullshit.
- If I want to call my husband, I can do so by pressing a single
dedicated physical key which is dedicated to him. No menus. The
point isn't to use the rotary dial every single time I want to make
a call, which would get tiresome for daily use. The people I call
most often are stored, and if I have to dial a new number or do
something like set the volume, then I can use the fun and
satisfying-to-use rotary dial.
- Nearly instantaneous, high resolution display of signal strength
and battery level. No signal metering lag, and my LED bargraph gives
10 increments of resolution instead of just 4.
- The ePaper display is bistatic, meaning it doesn't take any energy
to display a fixed message.
- When I want to change something about the phone's behavior, I just
- The power switch is an actual slide switch. No holding down a
stupid button to make it turn off and not being sure it really is
turning off or what.
So it's not just a show-and-tell
piece... My intent is to use it as my primary phone. It fits in a
pocket; It's reasonably compact; calling the people I most often
call is faster than with my old phone, and the battery lasts
almost 24 hours.
Open Source Design:
3/21/2020 UPDATE: The latest version of all this information will be
instead. The below links are left intact for posterity.
The build notes will be updated soon and can be found here
The build video is here
The firmware is on github here
The latest KiCad files (the complete electrical design) are here
The STL files for the 3D printed enclosure and buttons are on the
Originally I was intent on making this a quick and dirty project. I
laid everything out flat to make a proof of principle phone and used
an Arduino Micro as the controller:
Then I thought I'd just stuff it into a 3D printed enclosure. Let's
call this v1:
It worked but had all sorts of issues. Battery life less than 2
hours. Used the Adafruit FONA 2G, which was a big mistake because I
didn't realize the 2G networks are shutting down. Tantalizingly close
to having the phone I really wanted.
New design again. This is the final/current version. Whereas v2 used
the ATmega2560 microcontroller, v3 uses the ATmega2560V, which is the
low-power version of the chip. It's programmed in the Arduino IDE as
though it's an Arduino Mega2560.
Top level schematic:
This doesn't work. The bastard:
The layout looks like this. All the real KiCad design files are
available in the link above:
Debugging the serial connection to the FONA:
Note the Rigol MSO1104Z in the background. A WONDERFUL random present
from my husband David one year:
Complete, top down:
Showing the ePaper display:
The curved ePaper on tha back was a later development in the
creative process but it's now my favorite part. I think of the screen
as having two sections... the part that's facing toward the top of the
phone, and the part that's wholly on the back. In this way I can have
relevant messages display on the top part "pager style", like the most
recent missed call:
And still have the back available for other messages, or for
contacts lists, etc: