New firmware release for FCDEV3B and Tango/Caramel2

[Mychaela Falconia]

Hello FreeCalypso community,

I got new compiled firmware releases for our FCDEV3B and Tango modems:

ftp://ftp.freecalypso.org/pub/GSM/FreeCalypso/fcdev3b/fcdev3b-prod-fw-20210811.tar.bz2
ftp://ftp.freecalypso.org/pub/GSM/FreeCalypso/Tango/tango-modem-fw-20210811.tar.bz2

Compared to the last release for each respective target (20200720 for
FCDEV3B and 20201020 for Tango), the present release marks the
transition from Magnetite to Tourmaline source tree.  Most of the new
developments in Tourmaline affect only the handset configuration and
not the AT-command-controlled modem config, but there are two changes
which matter for modems too:

* Nucleus PLUS RTOS: Magnetite used the original TCS211 version of
Nucleus for which we have no exact corresponding source, whereas
Tourmaline (just like Selenite) uses FreeNucleus by Comrade XVilka,
compiled from source.  As a result of this change, we are no longer in
the situation where the source we look at for study and understanding
and the code we actually run are subtly different.

* Tourmaline fw now has L1_NEW_AEC enabled, meaning that the ARM fw's
handling of the DSP AEC block now matches the underlying reality of
what actually runs in the DSP.  Anyone who is interested in playing
with the Acoustic Echo Cancellation feature in the voice path on our
FC modems will need to run the new firmware.

Critically important: you MUST flash the correct fw build for your
board type!  If your board is FCDEV3B, then you can only flash fw
builds compiled for target fcdev3b, and if your board is Caramel2 (or
perhaps your own custom board using our FC Tango module), then you can
only flash fw builds compiled for target tangomdm.  The two builds I
just released were made from the exact same source version, but they
are not interchangeable!  There is a slew of hw differences between
FCDEV3B and Tango, and the selection of build target (fcdev3b or
tangomdm) causes the firmware to be compiled appropriately for each
different hw.

A reminder as always: if you do not currently have any FC hardware but
would like to play with our chipset+board+firmware solution, Caramel2
boards are very cheap ($220 for a complete kit, or $150 for a more
basic kit where you provide your own 3.3V or 2.8V UART or DUART), and
I am also open to the possibility of giving them away for free if the
recipient can demonstrate some loyalty to the cause and mission of
FreeCalypso.

Hasta la Victoria, Siempre,
Mychaela aka The Mother