New FC hardware on the horizon

Sun Sep 20 22:32:39 UTC 2020

Hello FreeCalypso community,

I just snapped some pictures of our new DUART28 adapter:

https://www.freecalypso.org/members/falcon/pictures/duart28/

The set includes front and back views of the DUART28 board itself,
plus a picture showing how the new adapter connects to our FCDEV3B.

This DUART28 is our new official adapter for connecting to the two
Calypso UARTs on our FC developments boards from a regular PC or
laptop or other USB host.  It will work with our upcoming Caramel2
development board in exactly the same way as how it currently works
with FCDEV3B.

The next step is to get our new Caramel2 boards made.  The slow email
exchanges with my PCB fab and with my assembly shop to nail every last
detail, to dot every i and to cross every t are finally drawing to
resolution, and I am hoping to submit the order for PCB fabrication in
the next couple of days.  Bare PCB panels should then be arriving some
time in October, and I am hoping to have assembled boards in November.

One of the major goals of this whole exercise is to make our full
uncrippled FreeCalypso solution (as opposed to much poorer Calypso
devices from Motorola or Sysmocom) available to the community at a
more affordable price.  Right now the price of FCDEV3B hw is $500
regular, and I also have 3 older FCDEV3B V1 boards on clearance for
$300 each.  The past few years have proven that these prices are too
high for most folks - but I am hoping that the new Caramel2 board will
be much cheaper: I am still shooting for the target price of $150 for
C2 with the needed power supply but without DUART28, or $220 for a
complete kit with DUART28 included.  (DUART28 is the best adapter, but
if someone is really poor, then they should consider the option of
buying a kit without DUART28 and using some cheap no-name FT2232x
adapter from ebay or aliexpress etc instead.)

One very major difference between our FreeCalypso family and our
ideological competitor OsmocomBB is that old Motorola phones (which
have always been and probably still are a perfectly fine hw platform
for OBB) have *never* been a good hw platform for FreeCalypso.  There
are several major ways in which those old Motorola phones are crippled
compared to our proper FC hardware:

* Their flash is brickable, and our firmware needs to be flashed, as
opposed to run-from-RAM only;

* They only have one Calypso UART accessible and not both, preventing
the user from playing with full FC functionality like CSD and GPRS;

* The physical form factor of a phone handset is quite inconvenient
for playing with fw configurations that are meant to function as a
modem, yet those phones can't run our full handset fw in its native
form either because of their small LCDs: our full handset fw requires
176x220 pix of LCD real estate, but Mot C1xx phones only have 96x64.

All of the above considerations are don't-cares for running the ultra-
primitive fw offered by OBB, but they matter for our more powerful
FreeCalypso fw that expects more out of the underlying hw - hence all
of the above considerations have been the driver for designing and
building our own FreeCalypso hw that is specifically made for the
purpose of running FreeCalypso rather than OBB.  The desire for hw
that is specifically made for running our TCS211-based FreeCalypso fw
is the reason why we designed and built FCDEV3B in the past years
(design started in 2015, culminating in physical hw built in 2017),
and it is also one of the drivers behind the current Caramel2 project.

FC Caramel2 will be a 118x86 mm development board, about 2.25 times
bigger than our current FCDEV3B.  The larger size is needed to make
room for additional expansion interface connectors: the new dev board
and the FC Tango module it is based around bring out a lot more
Calypso+Iota chipset signals, allowing optional add-ons like our
lovely FC Luna LCD (176x220 pix, TFT color, 16-bit parallel for our
full handset UI fw), 5x5 keypad, battery charging controls and more.
All of these interfaces are optional: you will be able to run the new
board by itself without connecting anything to the expansion interface
and it will work just like FCDEV3B (except for being quadband, another
nice benefit), but the extra interfaces are there for whose who wish
to play at more advanced levels.

Another nifty feature: if you look at the photos of our new DUART28
adapter which I just posted, you can see a little 3-pin header with
pins labeled GND, CTL1 and CTL2.  There will be a corresponding 3-pin
header on the Caramel2 board, with CTL1 becoming PWON and CTL2
becoming RESET.  If you connect this optional 3-wire interface between
the two boards (in addition to the main 10-wire interface carrying the
two Calypso UARTs), you will gain the ability to control the Calypso
board's switch-on, switch-off and reset functions programmatically
from your connected host computer over USB.  If you've already been
playing with our current FCDEV3B, you should thoroughly understand
what this board's PWON and RESET buttons do.  Caramel2 will have
exactly the same PWON and RESET buttons as FCDEV3B, but they can also
be triggered programmatically (without needing a human to press
buttons) in the new setup.  Connecting DUART28 CTL1 and CTL2 to drive
Calypso PWON and RESET is also possible on FCDEV3B - albeit less
conveniently - and I've already used this setup to verify that the
DUART28 side works as designed.

But we also have a competitor: it looks like our European colleagues
over at Sysmocom are busily working on their own competing Calypso
hardware offering:

https://osmocom.org/issues/4030
https://osmocom.org/issues/4575

I very strongly and emphatically disagree with some of their key design
decisions, and it appears that Sysmocom engineers' countering opinions
are just as strong in the opposite direction.  Given how devoted
Sysmocom folks seem to be to their idea, I am guessing that they
probably will take their design to production, and at some point their
CP2105+GTM900 hw will probably become available to the public via
their webshop.  I do need to warn the community though that the way in
which they are designing their board (and sticking to their design
despite my expert criticism) makes it very likely that their board
will be very poorly suited for running FreeCalypso: they will likely
build their hw offering in such a way that it won't be really usable
for any purpose other than running OBB.  The actual GTM900-B modem
modules on their carrier boards will probably still have Huawei's
original fw in their flash (OBB fw is not flashable, it is run-from-RAM
only, hence they won't be able to ship modems flashed with OBB even if
they wanted to), but I find it noteworthy that the particular way in
which they are repurposing modem controls into power controls (all
thanks to that crappy CP2105 chip which they insist on using instead
of FT2232x) will likely make their hw platform quite poorly usable
even with Huawei's original official fw!

The prospect of a vendor of extremely high reputation and community
standing like Sysmocom being about to offer what I consider to be a
mediocre Calypso hw product to the worldwide GSM tinkerer and
enthusiast community is rubbing me the wrong way, and I found it to be
my dame's duty (a dame is a female equivalent of a knight) to produce
and make publicly available a better alternative.  I have been working
quietly on the upcoming FreeCalypso Tango+Caramel2+DUART28 solution
since June of this year, I have invested about $9000 in total into
this project so far just between June and now (still got a few expenses
remaining before full completion), and right now everything appears to
be on schedule for delivery by December of this year.  It is possible
that Sysmocom's version may reach public availability sooner, but if
that happens, don't despair: the wait for our superior alternative
won't be long.

Hasta la Victoria, Siempre,
Mychaela aka The Mother