Silabs Aero II transceiver datasheet?

Mychaela Falconia mychaela.falconia at gmail.com
Fri Apr 26 22:42:37 UTC 2019


Hello OBB gang,

The Potential Calypso Targets page in your wiki lists a whole bunch of
phones with Silabs Aero II (Si4210) RF transceivers:

http://projects.osmocom.org/projects/baseband/wiki/PotentialCalypsoTargets

I wonder, has anyone ever succeeded in finding a datasheet for this
transceiver?  I found the datasheet for the older Aero+ transceiver
(a 3-chip solution), but not for the single-chip Aero II aka Si4210.

Here are the Silabs Aero materials I have found so far:

ftp://ftp.freecalypso.org/pub/GSM/Silabs/

I got the marketing briefs for Aero+ and for Aero II, and the full
technical datasheet for the former of the two.  If anyone has a
datasheet for Si4210 and would be willing to share it, I will gladly
add it to the above collection.

In the interest of full disclosure, if I get a hold of this datasheet,
adding it to the above FTP archive may be all that I will ever do with
it: even if I had the datasheet, I do not currently have any realistic
plans of adding Silabs Aero RF support to FreeCalypso, let alone to
OBB.  I do have a couple of Motorola W220 phones on their way to me
from ebay, and hopefully at least one of them will actually make it to
me, unlike the first one that appears to have fallen into a black hole
somewhere, but even with ideal documentation (full schematics and chip
datasheets), adding support for a very different RF subsystem (in
particular, Silabs' way of doing AGC is entirely different from TI's
way) would require more systems engineering work than I can do at the
moment.  It also doesn't help that the only tpudrv12.c reference TPU
driver we have is a reconstructed source made from the disassembly of
tpudrv12.obj, not TI's original source - thus all quarter-bit timing
numbers (there are lots of them, and they are very critical) are just
"magic" numbers, and their original derivation has been lost - does
not bode well for the task of figuring out what the corresponding
timings should be for a different RF transceiver.

All that being said, however, this Si4210 transceiver does look like
an attractive alternative to TI's Rita: the Si4210 is 5x5 mm compared
to TI's 7x7 mm (every square mm counts in a tightly squeezed modem
module), and it has 4 separate LNA inputs for the 4 GSM bands, to be
contrasted with Rita and Aero+ arrangement of 3 LNA inputs, one of
which is shared between EGSM and GSM850.  The Si4210 way with 4
separate LNA inputs allows a fully quadband MS to be implemented in a
much more straightforward way.  Thus tracking down a datasheet for
this Silabs Aero II transceiver and adding it to the knowledge base
should be a good step for the GSM enthusiast community as a whole.

I already tried asking Silabs for the datasheet, and got the answer
that the product line in question was sold to NXP back in 2007.
Reading up on Wikipedia, it appears that this stuff did not stay long
with NXP either, transferred first to ST-NXP Wireless and then to
ST-Ericsson, and when the latter closed, it is totally unclear where
the Silabs Aero stuff went, other than the great bit bucket in the
sky. :-(

M~


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