GTM900 support update

[Serg l]

I found this listing on the UK eBay
https://www.ebay.co.uk/itm/New-Huawei-GTM900-P-GSM-Modem-Module-/282012574494
They ask international buyers to contact them, so I'm waiting for reply
now. In worst case I can ask my contacts in UK to buy a few samples locally
and send to US

On Tue, Jun 18, 2019 at 2:05 PM Mychaela Falconia <
mychaela.falconia at gmail.com> wrote:

> Serg wrote:
>
> > Thank you Mychaela, this pretty nice platform as an alternative to C1xx
> > phones. While it is not as robust as FCDEV3B, it makes it a usable
> platform
> > for some applications development.
>
> For anyone interested in playing with FreeCalypso just for fun and
> recreating as closely as possible the environment which TI's own sw/fw
> developers had in their offices or cubicles Back In The Day, this new
> GTM900 find is definitely better than Mot C1xx, and only one step below
> my FCDEV3B, which is in turn one step below TI's own D-Sample board
> for which we have no schematics (thus no complete understanding), no
> PCB layout files (thus no ability to make more of those boards) and no
> tpudrv10.c module.  The main advantages of GTM900 over C1xx are (1) it
> is a modem rather than a phone, thus runs modem fw more natively
> without VPM hacks, (2) both UARTs are brought out, allowing the full
> TI/FC dual UART architecture to be fully enjoyed with GPRS, CSD and
> the GSM 07.10 MUX, and (3) the GTM900 is unbrickable unlike C1xx.
>
> OTOH, for commercial applications needing a GSM/GPRS modem module, the
> two biggest differences between the already existing and available
> GTM900 and what I seek to produce if anyone ever funds it are (1) my
> module would be at least triband and preferably quadband, and (2) my
> module would have Calypso MCSI brought out for a digital voice
> interface as recently proven on the FCDEV3B, a feature not present in
> any of the historical commercial packaged modem modules with the
> Calypso chipset.
>
> Also if anyone ever does fund the development of a new FreeCalypso
> commercial modem module, I would like to make it more modular, excuse
> the pun: instead of making a module with connectorized interfaces like
> GTM900 from the get-go, the first version (the most basic core) should
> be an SMT module more like BenQ M32, and once we have this basic core,
> repackaging it into a form factor more like GTM900 for those who
> desire such would be trivial.  The rationale is that an M32-like
> module can be trivially transformed into a GTM900-like one, but not
> the other way around.
>
> > I have done a quick search for a dev board schematics and here is an easy
> > find.
>
> On a short timescale schematics like the one you found aren't of any
> help, as it is just schematics, not a PCB design which one could send
> to a fab.  On a longer timescale where I will be doing my own PCB
> design for the breakout/interface board, those schematics aren't of
> much interest either: they don't tell me anything I didn't already
> know, and my version will be different in several ways.
>
> > I also found this document which describes some other variants of GTM900.
> > Looks like 850/1900 band is supported in GTM900-P
>
> Now this one looks interesting!  The PCB inside GTM900-B is designed
> so it can be populated in one of two ways, for either dual-eu or
> dual-us bands, so perhaps GTM900-P is the latter version indeed.
>
> > I'm going to get one and decap.
>
> I searched for places to buy a GTM900-P, and found only two sellers on
> Alibaba (not Aliexpress), one listing the price as $50-90 and the other
> as $50-99 per piece.  Assuming that single unit quantities would be on
> the upper end of this range, it is certainly more expensive than what
> our friend Songbosi is selling the EU-band version for, but looking at
> it the other way, it would still be cheaper than the cost of having
> Technotronix and Falconia Partners LLC modify and recalibrate these
> modules in California at USA fair labor rates.
>
> M~
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