FreeCalypso in 2018

Mychaela Falconia mychaela.falconia at
Mon Jan 1 02:50:04 UTC 2018

Hello FC community,

Happy 2018 to all of you!  2017 has been a reasonably productive year
for FreeCalypso: we have built our first non-historical Calypso board,
putting to rest all speculations as to whether or not such a feat is
possible, we've acquired our own production RF calibration capability
matching what the historical Calypso device manufacturers did, and
fully deblobbed firmware for the Standard Modem functionality is now a
reality: our current Magnetite hybrid config has no blobs except for
Nucleus and some parts of GPF.

As for the most recent accomplishments (as in the past few days), I
have reworked our new FreeCalypso battery charging driver (FCHG) to
maintain the constant charging voltage during the CV phase of the
Li-ion charging process by way of a software control loop, reverse-
engineered from Pirelli's fw, and this new charging implementation
works both on the C139 and on the Pirelli.  I have also created a new
hybrid-vpm (voice pseudo-modem) build configuration in FC Magnetite:
it is the TCS2/TCS3 hybrid config with CSD, fax and GPRS disabled,
matching Citrine.  This configuration is optimal for running on the
C139 and the Pirelli, i.e., on targets where CSD, fax and GPRS
functions cannot be exercised for lack of a suitable UART.  Voice and
SMS functions work just as well in this hybrid-vpm config as they do
in its data-services-enabled bigger sibling.

My goal for 2018 is to have a FreeCalypso phone with a working UI: the
lack of a non-broken UI is currently the *only* thing that keeps us
from being able to turn a Motorola C139 into a Libre Dumbphone, now
that we've got battery charging, we have radio operation with
Motorola's factory RF calibration values, and we have confirmed that
there is no large parasitic current draw on the battery when we run
our own FC firmware on the C139, unlike the situation on the Pirelli.

In pursuit of the FreeCalypso UI goal, I am going to make an attempt
to run FC Magnetite on the D-Sample board (TI's own development board
of which I have one specimen), which will include an attempt to fish
the tpudrv10 (TPU driver for RF type 10) code out of the ancient
20020917 fw image that came with this board.  If this idea succeeds,
we'll be able to use the D-Sample board to whip the UI code into
shape, then port it over to the C139 and have our first practically
usable FreeCalypso phone on C139 hw without waiting for our own
FreeCalypso dumbphone hardware.  However, I am going to put a bound on
this effort, and if recovering the necessary tpudrv10 code from the
20020917 fw image proves too difficult, I am going to switch my
efforts to designing and building our own Handset Motherboard
Prototype (HSMBP) that will be able to replace the D-Sample as the UI
development platform.

On the hardware front, I am happy to report that I found someone who
is willing to sell me their Openmoko tri850 device, I've already paid
for it, and it should be arriving in the next few days once the
working world reopens.  When this trophy arrives, I will take it apart
and examine the 850 MHz downlink receive path, and then we'll
hopefully gain the knowledge of how to build tri850 devices of our
own, in addition to our current tri900 ones, and also the ability to
convert any existing Openmoko-made unit between the two band
configurations in either direction.

In terms of geography, there are very few areas in the world where the
GSM850 band may be needed: it is NOT needed in USA (no more Cingular/AT&T
GSM here, only T-Mobile left, using only the PCS band), and it is
certainly not needed in any of the EMEA or Asian regions.  Thus the
only places in the world where the tri850 configuration may be
advantageous are Latin America and possibly Canada (not certain),
while for use everywhere else the more classic tri900 configuration
remains the best choice.  Thus the tri900 config will always remain
our primary offering, but it will be nice to offer tri850 as well for
the sake of completeness.

Hasta la Victoria, Siempre,
Mychaela aka The Mother

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