Paul van der Vlis <[email protected]> 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~ _______________________________________________ Community mailing list [email protected] https://www.freecalypso.org/mailman/listinfo/community
