Free board offer to OBB developer with a CMU200

Mychaela Falconia mychaela.falconia at gmail.com
Sat Apr 6 21:14:55 UTC 2019


Craig wrote:

> I am determined to make a compliant phone of my own design which includes
> osmocom-bb.
> I must work slowly but will continue to work.

It sounds like your desire to produce a practically usable phone with
OBB and MTK chips is as strong as my desire to produce a practically
usable phone with TI chips and TI-based firmware.  I have been working
toward my goal since the fall of 2013 (when the liberation of the
world's last surviving copy of TI's TCS211 abandonware from the "we
won't share" gang made it possible); what I have to show so far is
that I got a commercial-quality modem (with full source code freely
published) that would most certainly pass the full type approval test
if someone paid for it, but no phone UI yet.  In order to turn this
FreeCalypso modem of mine into a practically usable phone which I
could carry in my purse (pocket replacement for us ladies) instead of
the proprietary Pirelli DP-L10, I just need to do one more board design,
adding LCD, keypad, battery charging and other handset peripherals to
my proven-good modem board design.  But because of cost issues (this
handset board design will cost me a lot of money), I need to postpone
it until after my big surgery, not before, hence it will be another
few years.  In the meantime, the modem (phone sans UI, control via AT
commands) is already 100% working and is available today.

Now please present your story (meaning Craig) - how long have you been
actively working toward your respective goal?  What do you have to
show so far?

> progress on porting layer1 to mediatek chips.

Would you mind clarifying exactly what your OBB-on-MTK layer1 can do
today?  Can it do a power scan across the band to find the ARFCNs of
likely GSM cells?  Can it sync to the frequency burst of a cell?  Can
it receive the synchronization burst and sync to the multiframe
structure?  Can it receive a cell's broadcast info on BCCH and CCCH?
These are the things which OBB on Calypso could do back in 2010.  Or
zooming out more generally, do you have *any* control of the radio
hardware (say, frequency synthesizer or other components of the Rx
chain) in your OBB-MTK-L1?  Do you have *any* understanding of MTK's
DSP and how to talk to it?  I hope you realize that every commercial
GSM baseband processor, be it from TI or MTK or any other vendor,
includes a DSP for signal processing functions, and that one *cannot*
meaningfully receive or transmit any GSM signals without having a
thorough understanding of that DSP and working with it...

The people who created OBB on Calypso back in 2010 used two key
sources of knowledge in order to learn how to work with Calypso's DSP:
one source of knowledge was the well-publicized TSM30 source, but the
other, much less well-known one was the TCS211 semi-src.  Both TSM30
and TCS211 versions were absolutely critical to their success; the
TSM30 version by itself would NOT have been sufficient for figuring
out how to drive the Calypso+Iota+Rita chipset in Mot C1xx phones,
which is quite different from the much older TI baseband + non-TI RF
in the TSM30 phone.  Instead the TCS211 semi-src was *the most
critical* piece for working with the Calypso+Iota+Rita chipset, but
being a semi-src rather than full source, it had to be supplemented by
some other TI source: either TSM30 (what OBB founders used) or LoCosto
(what I used instead), still in conjunction with TCS211.  Do you have
an equivalent source of knowledge for MTK's DSP?

Just trying to see if you have anything real and tangible to show for
your idea of OBB on MTK, that's all...

M~


More information about the baseband-devel mailing list