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~
Following up on this inquiry, the datasheet in question has been located - one of the long-timers here sent me a copy. It has now been added to the archival collection:
ftp://ftp.freecalypso.org/pub/GSM/Silabs/
I am now waiting for one of those Mot W220 phones I ordered on ebay to actually arrive. I ordered the first one back on April 1 from a seller in Albania, and it appears to have fallen into a black hole somewhere: the seller marked it as shipped, but there is no tracking number, and it has been almost a month. (The "estimated delivery" says April 16 to May 2, thus another week before I can report it to ebay as not delivered.) Giving up on that one, I ordered two more yesterday, one from Serbia and one from Canada - hopefully at least one of them will arrive.. And I did find the schematics for this phone, yay - if anyone needs them, I can add them to the FTP site.
The notes in the OBB wiki say that Mot W220 has the Calypso boot ROM enabled and that it is accessible via the headset jack with the same cable as on Compal-made C1xx models, and the schematics seem to concur, so I am hopeful... But here is a mystery: there is another very seemingly-similar phone called C168, it is from the same time period and has essentially the same components, and it is mentioned on the same Potential Calypso Targets page as the W220, although it just lists the use of the Si4210 transceiver but says nothing about code download access. I already have one of those C168 phones - it was much easier to get than W220 because there are plenty of USA sellers for this model (AT&T carried them as basic prepaid phones just like the C139) - but I had zero luck in getting bootloader access through the headset jack on this phone. Unlike with the W220, I also had no luck in finding any downloadable schematics for the C168, so I don't know if this model has the boot ROM disabled via nIBOOT unlike the W220, or if the headset jack does not function in UART mode until the firmware configures it for the AT command interface after boot, or what.
Has anyone else tried gaining code download access on the C168? Was your experience the same as mine? Has anyone figured out where the blockage is?
Frustrated, Mother Mychaela with her curious-as-a-cat tinkerer hat on
baseband-devel@lists.osmocom.org
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Mychaela Falconia