Looking for Leonardo+ PCB layout

Michael Spacefalcon msokolov at ivan.Harhan.ORG
Tue Oct 15 18:18:14 UTC 2013


As I wrote here two months ago, I am seeking to build my own totally
free, end-user-usable Calypso-based quad-band GSM plain phone, as well
as possibly a Calypso-based free GSM modem module for smartphone
projects done by others, such as this:

http://talk.maemo.org/showthread.php?p=1376708

I already have the Calypso etc chips in qty 100 sitting in my desk
drawer - buying them on the Chinese surplus market turned out to be
surprisingly easy, and they most definitely have quite a bit more of
them available than the 100 I have bought.

Making my GSM device(s) quad-band as in 850/900/1800/1900 MHz is an
important part of my goal - contrast with the current OsmocomBB-
supported devices, which are only dual-band or tri-band at best.  My
belief in the idea that our familiar Calypso/Iota/Rita chipset is
capable of supporting the quad-band configuration stems from the
existence of this TI reference design:

ftp://ftp.ifctf.org/pub/GSM/Calypso/Leonardo_plus_RD122.pdf
ftp://ftp.ifctf.org/pub/GSM/Calypso/Leonardo_plus_quadband_schem.pdf
ftp://ftp.ifctf.org/pub/GSM/Calypso/M034F.pdf

The first PDF is something I just found on 52rd.com 2 days ago: it has
the Leonardo+ quad-band schematics plus a component placement drawing.
The 2nd PDF is the schematic which we have had for 2y now (might be a
very slightly different version, haven't visually diffed the two
closely enough) and the last PDF is for the quad-band RF FEM they used,
all from 52rd.com.

What I am still missing is a copy of the PCB layout (in whatever format
TI used for their reference designs all those years ago) corresponding
to those schematics.  I have not yet found that article in my trawls
through 52rd.com - that's a search for a needle in a giant haystack.
(We also have a Leonardo_rev05.dsn file, in the same directory as the
ones listed above, but I assume it's the EDA source file for the
schematic capture phase only, no layout.)

I have already found a layout for a dual-band phone on an 8-layer PCB:

ftp://ftp.ifctf.org/pub/GSM/PCB/unknown-phone-pcb1.zip

and I can probably find a layout for a tri-band phone on an 8-layer
PCB too, something like Pirelli DP-L10.  In contrast, Leonardo+ is a
very elegant quad-band design, and this TI doc says it's only a
6-layer PCB:

ftp://ftp.ifctf.org/pub/GSM/Calypso/chipsets+refdesigns.pdf

(see page 10)

We also have this:

http://scottn.us/downloads/peek/HW%20doc/I-Sample%20ref.%20design/Full%20package%20-%20I-sample%202.7/

I-sample is TI's LoCosto board, and it is quad-band.  But LoCosto's
built-in RF block has separate LNA inputs for 850 and 900 MHz unlike
Rita, and I-sample uses a weird arrangement: the PA and the antenna
switch are integrated into one, but the Rx SAW filters are discrete.
So it isn't the same as Leonardo+.

Thus I am putting out this loud call for anyone who may have found a
copy of the Leonardo+ PCB layout somewhere on 52rd.com or some other
site of a similar nature.  If you have a copy of this PCB layout or
know of a place where it can be downloaded, please speak up!

By helping me obtain a copy of that PCB layout, you would be helping
not only me, but also all those end users who would appreciate having
a quad-band GSM plain phone (or a modem for Neo900 etc) that is fully
documented and capable of running 100% free baseband firmware.

TIA,
SF




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