FreeCalypso end user phones

[Mychaela Falconia]

David wrote regarding the Pirelli phone:

> But then M says that the undocumented wifi chip will be a show stopper
> - what a pity!

Actually the undocumented camera chip (SPCA552E) is an even bigger
problem than the undocumented WLAN chips.  So far I haven't run into
any total show-stoppers: we *can* run our own fw currently on the
Pirelli without the UI, with control via AT commands over RVTMUX over
USB-serial, and if someone were to add an LCD driver based on
OsmocomBB's reverse eng and implement a 128x128 pixel UI, it will
probably work as an untethered phone.  But:

1) We don't know if all of those undocumented chips which we leave
   untouched will cause a problem or not - who knows, maybe they are
   going to draw power and kill the battery unless the fw does the
   right magic to put them into sleep or powered-off mode, magic which
   we lack.

2) We don't know how to control the loudspeaker driver and ringtone
   generator chip: we do have some docs and driver code for the W56940
   chip itself, but its circuit connections on the Pirelli have not
   been fully reversed.  I stopped my investigation in that direction
   when I traced its reset line and found that it is driven by the
   undocumented camera chip.

Someone else could try ignoring the reset line, trace out the rest of
W56940's control signal connections to figure out how to address it,
try talking to this chip ignoring the reset issue and see if it works,
but it is not something that I am personally willing to invest my time
and energy into.

In our current state with no ability to control that W56940 chip, we
cannot make the phone ring or turn on the hands-free loudspeaker.  We
can make the phone vibrate (I accidentally found that their vibrator
is hooked up in the place of the piezo buzzer), but would you want a
vibrate-only phone with no ringing ability?  And if we are unable to
turn on the hands-free loudspeaker, that destroys the primary value of
this phone over the competition in my view.

> Glad to hear that the dev board has been so successful.

For those who desire a FreeCalypso end user phone (that includes me),
the right approach is to build on this success and take further steps
toward our own Libre Dumbphone hardware product.  The remaining FCDEV3B
bring-up steps which I am still working on (finishing the automated
calibration software, debugging the minor miscellaneous hardware
problems we are having, and exercising the analog audio circuits) are
needed not only for the FCDEV3B itself, but also for any future FC
hardware products derived from it, hence these steps are necessary for
the end user phone product as well.

As I wrote earlier, I already have a plan in mind for the next
development board after the FCDEV3B, which will be a handset motherboard
prototype (HSMBP).  Add a 176x220 pixel color LCD (even bigger than
Pirelli's, and will allow us to use TI's 176x220 pixel prototype UI as
our starting point), a keypad and a few minor tweaks, and we'll have a
dumbphone motherboard no worse than the Pirelli in terms of features,
but fully libre without those undocumented chips.

And I have already proven that we can generate pleasant-sounding
ringtone melodies using the Calypso DSP alone, with just a dumb
loudspeaker amplifier like on the FCDEV3B, without using a MIDI player
chip like in the Pirelli or in Mot C155/156 - see my doc/Melody_E1
article in the freecalypso-tools repository.

Hasta la Victoria, Siempre,
Mychaela aka The Mother