Perfect module (D751749ZHH)

[Mychaela Falconia]

Hi Songbosi,

> 1) I havn't test it's nIBOOT pin, I have dump the flash with gtm900-b
> with your fc tool
> https://app.2sim.cn/gsm/gtm_full.bin

The fact that you were able to get in with fc-loadtool indicates that
the boot ROM must be enabled.  Can you please explicitly confirm that
you can run tools like fc-loadtool or osmocon -m romload against the
GTM900-B without needing to do anything via JTAG first?  The reason I
am asking is because your very first introductory post about this
module showed JTAG test pad locations, giving the impression that JTAG
is required in order to work with this module.

> 2) I modify this for 900/1800 switching,  using gta02 OsmocomBB
> [...]
> https://app.2sim.cn/gsm/rffe_gta0x_triband.c

Your code indicates that on this module TSPACT1 is the low band Tx
enable and TSPACT2 is the high band Tx enable, both active low - is
that correct?  If so, then Huawei must have reversed these two control
signals relative to TI's Leonardo reference design, where they go the
other way around: TSPACT1 to enable high band Tx and TSPACT2 to enable
low band Tx, plus TSPACT4 to control the GSM850 Rx switch which is
only present on quadband boards.  Openmoko's design permutes these 3
RFFE control signals in yet another way.

Aside from this little TSPACT RFFE control signal permutation, I find
it very remarkable that this Huawei modem is so close to TI's reference
design!  Up until now it seemed to me that Openmoko was literally the
only Calypso-based modem manufacturer in the world who kept TI's
reference design (both hw and fw) with absolutely minimal changes,
while every other phone (Compal, Chi-Mei, Foxconn) and modem (BenQ M32)
manufacturer changed both the hardware and the firmware beyond all
recognition.  I am glad to see Huawei stand next to Openmoko in this
regard!

As far as Huawei's firmware design goes, looking at your flash dump,
I was just as delighted to see a classic TIFFS file system structure
in the same flash location as on OM's modem (looking at your pictures,
it looks like this module uses the same Samsung flash chip as was used
by OM), and examining that file system content with my tiffs tool (I
can even use the same mokoffs user-friendly wrapper!), I see that it
contains TI's classic RF calibration tables!  Getting FC Magnetite and
Selenite firmwares to run on this modem hw is promising to be a
breeze. :-)

> 3) I would ship this module to US with fpc connector, you can just using
> an USB to UART adapter to get it work with PC
> https://app.2sim.cn/gsm/fpc.jpg

OK, I would like to buy 3 pieces from you - please email me off-list
to work out payment and shipping.

M~