FreeCalypso on Mot C139 back on the agenda

[Mychaela Falconia]

Hello FreeCalypso community,

Right now there is a possibility that I may be reopening the idea of
producing a "FreeCalypso Lite" phone by way of aftermarket firmware
running on historical Motorola C139/140 hardware; the purpose of this
announcement is to gauge whether or not there is still any community
interest in this idea.

We have had non-practically-usable proof-of-concept FC firmware that
runs untethered with a primitive PoC UI on C139 hw since 2015, and
since 2018 we have had rock-solid lower layers for this target, namely
fully compliant GSM radio operation using original factory calibration
data and battery charging using our own FreeCalypso original driver.
For the past two years, the *only* missing piece has been high-level
UI firmware work, i.e., the work to fix various bugs in TI's demo/
prototype UI code and bring it up to par.

During all of the time up to now, I have been very reluctant to make
heavy-duty changes to TI's demo/prototype UI code (the kind of heavy-
duty changes that would be needed in order to bring it up to par and
make it practically usable as a phone) because I was not and still am
not willing to give up the other "big color" configuration.  TI's PoC
UI code can be built in two configurations, targeting either the large
color 176x220 pixel display on TI's D-Sample platform, or the small
black&white 84x48 pixel display from TI's earlier platforms, meaning
C-Sample and earlier.  The PoC UI which we got running on Mot C139 hw
is the C-Sample version; further work can be done on this "small B&W"
UI version to extend it from 84x48 to 96x64 pixels (C1xx display size),
but the part which I was absolutely not willing to do (and still am
not) is to work *solely* on the small screen version of the UI,
permanently giving up on "big color" version and thus permanently
giving up my dream of some day building a true FreeCalypso phone - no
way will I ever give that dream up!  And because up until now we did
not have any workable development platform with a 176x220 pixel color
LCD connected to a Calypso core, all UI work ideas stood at a halt,
making no progress in any direction, C139 or otherwise.

But during the past few months there has been a breakthrough, and
there now exists a new in-house development platform here at
FreeCalypso HQ, a platform which I have named FC Luna.  Back in
December our dear Das Signal obtained two pieces of a very rare
Calypso development board (made by a non-TI third party) which we have
codenamed Caramel; this Caramel board has a Leonardo clone as its core
(thus trivially supported by FreeCalypso with fully working GSM radio),
plus one more very special feature: it has an expansion interface on
which many Calypso signals are brought out, including the 16-bit
memory bus (MEMIF) to which one can connect an LCD module with a
memory-mapped microprocessor bus interface, i.e., an LCD of the same
class as on TI's D-Sample and on the Pirelli DP-L10.

The new Luna UI development platform that has been put together at
FreeCalypso HQ consists of a Caramel board that has been reworked by
my friends at Technotronix to change the expansion interface to an
easier-to-work-with connector type, plus the Luna LCD carrier board
(add-on piece) that was designed and built by me, connected to the
expansion interface on the modified Caramel board with a hand-made
(custom pinout) ribbon cable.  The actual LCD module is a HaoRan
HT020K1QC36S, one of the several LCD modules which I had evaluated
back in 2018 and one of the two which I found to be good; it is a
176x220 pixel 16-bit color LCD with a 16-bit microprocessor bus
interface.  My custom hardware hacking ministrations result in this
nice LCD being connected to Calypso MEMIF on the modified Caramel
board and mapped into Calypso address space; FC Magnetite firmware
built for target luna runs on this platform and successfully displays
TI's original 176x220 pixel color UI on my Luna LCD, all while having
a fully working GSM radio at the same time!

Unfortunately I won't be able to share this Luna hw platform with the
community: while the Luna add-on piece designed by me can be produced
very cheaply and easily (the design files live in the fc-small-hw Hg
repository), it is rather useless without the Caramel motherboard, and
of the latter there are only two in the world - I have one and DS has
the other.  But while I am not able to share the development platform
itself, I am hoping to be able to use this dev platform to produce
some fruits which *can* be shared - and one possible fruit which I
might be able to produce would be FreeCalypso on C139 brought to a
practically usable state.

This new Luna platform has been put together into its working state
just earlier this week, and now is the first time in all of the years
of FreeCalypso that I've been able to run the "big color" version of
TI's PoC UI on a platform with working GSM radio (unlike the original
D-Sample board) and with instantaneous updates on the directly
connected LCD - as opposed to many seconds of lag when I tried reading
out the firmware's framebuffer over serial in the absence of a physical
display.  This is the first time in years that we are able to run TI's
original UI code in all of its glory, in all available configurations:
the "big color" config on the Luna platform, and the "small B&W" config
on both Luna and C139.

How will Luna help FC-on-C139 development?  My idea is as follows: now
that I can run the UI code in both "big color" and "small B&W" configs,
I can make bugfixes and other changes, and test both configs at each
step.  I reason that I should be able to work on the "small B&W"
config that runs on the C139, but thanks to Luna platform, do it in
such a way that does not break the "big color" UI config, leaving the
possibility open for my desired FreeCalypso dream phone.

I do need to set the expectations clear, though: for me personally,
Mot C139 running FreeCalypso fw can *never* replace my dream of a true
FreeCalypso phone (meaning phone handset hw designed by me, with me
rather than Motorola or some other historical manuf making every key
design decision), thus the scope of the work which I would be willing
to do for C139 on a volunteer basis (outside of paid contract terms)
will always be limited.  In particular, I am currently thinking of
keeping the small 96x64 pixel UI black & white - the physical LCD on
the C139 is 16-bit color (not sure if it is CSTN or TFT), but the only
"small" (smaller than 176x220 pixels) UI we got from TI is B&W.  I
currently feel that extending TI's "small B&W" UI from 84x48 to 96x64
pixels would be a significantly smaller job than designing a new 96x64
pixel color UI - the latter would involve significantly more creative
work, it seems to me based on my current understanding.  I can
certainly do it, but because Motorola hw is very uninspiring to me
personally, I currently feel that designing a 96x64 pixel color UI
would be something I would do only under a contract gig - whereas the
"all volunteer" version I am currently contemplating would be B&W only.

So what I am currently considering is developing a rather basic and
limited "FreeCalypso Lite" firmware for C139: it would be limited in
the sense of having no UI colors, no fancy ringtones beyond the most
basic, no other frills - but I would fix the critical bugs (crashing
etc) and add the parts of essential functionality which are currently
missing.  Anything else can be added later: the most basic minimal
functionality will need to be developed first, and right now we don't
have even that.

But here is the critical question: would anyone in our community be
interested in a working and practically usable (albeit very minimal)
FreeCalypso firmware version running on C139 hardware in 2020?  There
will be a much higher likelihood of me actually carrying through this
time - as opposed to dropping it again - if there is at least one
person seriously interested.  Thus if there is anyone still interested
in FC firmware for Mot C139 and who would be willing to use it as his
or her personal phone if I get it into a practically usable state,
please speak up!

Hasta la Victoria, Siempre,
Mychaela aka The Mother