Rotary Un-Smartphone Fixy Fix Update

Sat Dec 17 16:10:04 EST 2022

Since my last big update (11/15), in addition to fixing the critical 
issue of the rotary dial not producing numbers consistently, I wanted to 
fix as many of the other little issues I mentioned as possible. This is 
where I am with it, but there's a TL;DR at the end:

-Rotary dial reliability: *Fixed.* Hubby and I just took this clip the 
other day demonstrating the fingerstop position detection working: 
https://youtu.be/IzC9Kba0LX4
The video is showing debug firmware that's just flashing the white 
filament LED every time the fingerstop is detected at its end stop, but 
that's what was needed. HallSensor.jpg shows the main part of the actual 
hardware design change.

-Reception quality: *I think fixed.* I updated the daughterboard design 
too to improve the internal antenna to a newer and more capable antenna 
element. Daughterboard_BA.jpg shows the difference between old and new. 
The band coverage of the internal antenna now better compliments that of 
the external antenna.

-Aux. jack: *Might be fixed.* I learned the reason the auxiliary headset 
jack (the TRRS jack) wasn't working is because common headsets *always* 
use single-ended audio, (i.e. one wire connected to the audio source and 
the other connected to ground) and the audio codec on the RUSP provides 
differential output (a speaker with both wires receiving the audio 
waveform). I added a differential-to-single-ended audio output stage to 
make this conversion, meaning the built-in speaker and mic are now also 
single-ended. See AudioStage.jpg if interested. I don't know if this new 
audio stage works or not yet (reason below), but it should. Also, if you 
have a EE background and would like to be a second pair of eyes on the 
schematic, please email me.

-LEDs: Because the "meter" LEDs on the side of the phone are entirely 
redundant considering the front OLED display is much better at 
displaying battery level and signal strength, I decided to turn most of 
them "inward" to illuminate the rotary mechanism while it's turning. 
Just a neat aesthetic improvement. See NewLEDPositions.jpg.

-Battery life and speaker phone: *Probably both fixed.* The headline for 
this item is that***there's no longer a difference with the early-order 
beta-test phones.* It's all the newest possible chipset (LARA). If you 
want to know what this means and how it relates to the battery and 
speaker phone issues, by all means read on:

The phone was originally supposed to use a cellular modem from u-blox 
called "TOBY R-2". Over the course of designing the phone, I learned 
from u-blox that the TOBY series was reaching end of life and that the 
recommended replacement part is the u-blox LARA-R6. I'd already procured 
enough TOBY modems for the first 200 or so orders, but in the interest 
of having the best possible phone from the start I decided to transition 
immediately to the newest version of the cellular modem (the ublox 
LARA-R6) and NOT use any of the cellular modems that were designated for 
the early-order phones. Those chips are now on ebay. This was 
irresistible to me because the LARA has a much better low-power mode 
that doesn't sacrifice detecting incoming calls, et cetera, and which 
should at least double the phone's battery life. It also has pre-set 
audio codec profiles for things like speakerphone, which was also giving 
me trouble with the older (TOBY) cellular modem.

The catch: Because of a baud-rate compatibility issue between the new 
LARA and the phone's low-power microcontroller, I need to either 
somewhat customize the phone's microcontroller's bootloader, or switch 
to a similar, pin-compatible microcontroller (i.e. the ATmega1280, which 
can run at 16MHz while powered by a lithium battery, as opposed to the 
current ATmega2560V, which only runs at 8MHz), which should handle the 
higher baud rates naturally. So that's what I'm working on now.

*TL;DR: *The first-release of the phone is close to not having any 
compromises, but now I have to fix the new problem that was created by 
migrating to the newest cellular modem. I'm waiting for some new parts 
to arrive and plan to sort through these last problems in the coming 
week and get the first orders out the week after that.

*Final thing* for this email: I'm faced with the reality of having to 
sustain this company and be able to continue buying parts for future 
batches, etc. I haven't, I would say, intentionally sought pre-order 
customers before because there just seemed to be somewhat consistent 
interest, and with that I've been able to finance all the development 
costs with the pre-orders that just happened to come in. Kickstarter 
without the Kicstarter so to say. But, I'm starting to stress a bit 
about this as there are still long lead times on certain parts for 
future batches, and this requires a "front heavy" spending profile 
(yikes I'm turning into a business person).

Once phones are actually in customers hands the dynamic will be 
different and I'll feel OK about actually /trying/ to sell these, but 
for now I'm not entirely sure what to do. At a certain point I'll need 
to NOT be working out of a basement (I'm not sure if this is even 
legal), and hire a couple people to help with ongoing manufacturing. 
Making this transition from tiny business to less-tiny business is a 
known tripping point for small business development from what I can 
tell, but I guess I'm open to suggestions.

~Justine
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