February 17th, 2020 Update: KIT FOR SALE
I've been getting so many requests from people wanting to buy the rotary cellphone that I've decided to make it available in kit form. Builders will still need to find the right rotary dial and order a handful of other bits, but the "hard part" (the mainboard and the 3D printed casing with threaded inserts and buttons) is available for sale from my new robotics company here: skysedge.us
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 not texting.
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 functional how?
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.
Build notes, gotchas, and explanations here.
Design files (KiCad, firmware, mecanical STLs, BOM) available here.
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:
But this proved hopelessly delicate. Couldn't open it to fix something without breaking something else. OK, I guess a board layout is warranted. Did that and came up with v2:
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:
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: