Realistic plan for our own FreeCalypso phone

[Mychaela Falconia]

Paul van der Vlis <paul at vandervlis.nl> wrote:

> Another idea is to produce a board what fits into an existing case, e.g.
> by swapping the mainboard of a cheap dumpphone. In this way we could use
> some parts of the phone I would think, like the battery, antenna or the
> display.

Naturally this approach was my first idea during all of these years
that I've been wanting a FreeCalypso dumbphone - so yes, of course I
have thought of it.  But I don't think it's going to work, for several
reasons:

* We need to use a particular type of LCD: a 176x220 pixel LCD module
  with a 16-bit parallel interface.  And of course the electrical
  interface to the LCD module has to be *documented*.  No problem if
  we are shopping around for the LCD module on our own, but trying to
  reuse whatever unknown LCD happens to already be in some cheap
  dumbphone would be a non-starter.  And each LCD module is slightly
  different mechanically, hence the chances of a board designed with
  our own choice of LCD module fitting into a case made by someone else
  for some other LCD are nil.

* I intend to have a specific set of buttons: 21 buttons on the main
  keypad in the same arrangement as Mot C1xx and Pirelli DP-L10 (also
  matches TI's D-Sample), and 3 side buttons similar to the Pirelli
  and the D-Sample handset.  None of the case reuse candidates I have
  considered over the years perfectly matched this desired button set;
  at best we could have the 21-button main keypad but give up the side
  buttons - but I would really like to have the button set no worse
  than Pirelli and D-Sample.

* External connectors: we need to bring out a mini-USB charging+data
  port and a 2.5 mm analog headset jack to the outside of the phone.
  Once again, none of the case reuse candidates I've considered over
  the years fit the bill.

And then of course there would be other ugliness: all existing phones
have cameras but ours won't, hence the camera hole would be empty; all
existing phones have uSD card slots but ours won't, so yet another
unusable case hole, etc.  Ditto for the 2nd SIM slot on the many
currently made dumbphones - no corresponding capability on the Calypso.
Of course having unused extra holes that will stay open is not as bad
as not having fitting holes for the things we do need, but all of the
other problems listed above will still kill the idea before we get to
the point of deciding what to do with this or that hole.

> Or we could use a board what fits into the case of some standard
> hardware like a Raspberry pi or Arduino. I've tried it here with an
> Olinuxio Lime2 case, and it fits into my pocket.

This idea makes even less sense.  Where would the display go?  Where
would the keypad and other buttons go?

In any case, I already have my mind set on the plan which *I* consider
workable, and in situations like this one I feel that it is my place
as the Mother of FreeCalypso to set these kinds of key design decisions.
The plan is as follows:

1. Build the first development version of the phone board in such a
   way that all of its functionality can be exercised on a bare board
   without any case: LCD module mounted in a way that doesn't require
   a case for securement, buttons directly on the board, everything
   else via connectors.  Use this arrangement for handset firmware
   development: UI, battery management etc.

2. Once all circuit functionality has been validated and the full fw
   support has been developed on the bare board (easily a year or two
   after the board itself has been made), then either build a case
   around the as-is board, or respin the board to fit whatever case
   design is targeted, be it our own or someone else's.

And even the first step of this plan (building the bare development
version of the handset motherboard) would only begin some months after
we get the FCDEV3B built: remember, we still have to build our *first*
board (the FCDEV3B, the one for the crowdfunding campaign is running
right now), this board won't have any LCD or buttons at all (it's a
modem, not a phone), and only *then* we'll be able to start on design
of our next board for UI etc development.

I am going to post an update regarding the FCDEV3B next.

M~