# HG changeset patch # User Mychaela Falconia # Date 1623566599 0 # Node ID 42d53bfbcca31bf1c5c0311c0aaa867a58a4fcef # Parent da5113856f3b578a8e7c9381f890172b04786ff4 FC-handset-spec: Mot C139 idea documented diff -r da5113856f3b -r 42d53bfbcca3 FC-handset-spec --- a/FC-handset-spec Sun Jun 13 05:27:45 2021 +0000 +++ b/FC-handset-spec Sun Jun 13 06:43:19 2021 +0000 @@ -1418,3 +1418,117 @@ Also following the principal design of section 1.12.3, there will be a 3-pin header on the Venus board bringing out RPWON, nTESTRESET and GND, to be connected to the boot control header on DUART28C. + +4. Motorola C139 port + +4.1. Background information + +In FreeCalypso we have low-level support for the following alien targets: + +* Motorola C11x/12x +* Motorola C139/140 +* Motorola C155/156 +* Pirelli DP-L10 +* Sony Ericsson J100 + +Low-level support means that for all of these targets, we are able to build and +load a FreeCalypso firmware image that boots and runs without crashing, operates +the phone's GSM radio hardware in proper spec-compliant manner (transmissions +verified with a CMU200 RF tester), and allows control via AT commands and +FreeCalypso debug & development tools fc-shell, fc-tmsh and fc-fsio. However, +in this so-called "voice pseudo-modem" (VPM) operation, the phone's LCD stays +dark, the buttons do nothing, and there are no high-level functions of any kind, +only low-level control from the attached host computer. + +It also just happens that in year 2015 I (Mother Mychaela) produced a firmware +version for Mot C139 that runs untethered, without host computer connection. +However, that untethered FC-on-C139 firmware was produced as a poor man's hack, +not as an end user offering! Here is the situation we were in: we did not +discover the existence of iWOW TR-800 (an extremely obscure Calypso module) +until December of 2019, thus for the 4 years between 2015 and 2019 we had no way +of running TI's TCS211 MFW+BMI (handset configuration) firmware in its proper +D-Sample config, which is 176x220 pixel color. But we knew that TI also had an +older C-Sample UI configuration (84x48 pixel B&W), thus out of poverty, for the +lack of proper development hardware, we resurrected that old C-Sample UI config +(at first it wouldn't even compile) and got it running on Mot C139 hardware - +possible because that 84x48 pixel UI was small enough to fit into Motorola's +96x64 pixel LCD. + +To be clear, I *never* considered this hacky FC-on-C139 port to an acceptable +substitute or replacement for my real goals of first getting TI's TCS211 UI up +and running in its proper 176x220 pixel color configuration, and then producing +a FreeCalypso handset that can replace the proprietary Pirelli DP-L10. However, +a peculiar situation has arisen: we now know that it is possible to transform +Motorola C139 into a sort of Libre Dumbphone Lite with aftermarket FreeCalypso +firmware, and it is clear that some users will prefer this "liberated C139" +option over the Mother's desired FC Libre Dumbphone handset - probably for +reasons of cost more than anything, as our FC phone will likely end up costing +thousands of dollars. The rest of this chapter will explore the possibility of +practically usable FreeCalypso handset firmware on Mot C139 hardware. + +4.2. Why C139? + +As a matter of general principle, we could probably get our FreeCalypso Lite +firmware running on all or most of the 5 alien targets listed in section 4.1. +However, the level of usability and the set of user-available features on the +other 4 would only be worse than what we would get on C139, thus if someone is +looking for a pre-existing phone hw unit to convert to FreeCalypso Lite, then +C139 is the best choice in terms of outcome quality. + +It is particularly worthy of note that if we were to get FreeCalypso Lite +firmware running on Pirelli DP-L10 (it hasn't been tried as of this writing, +but it is likely possible), the result would be not only much much worse in +functionality than Pirelli's official firmware or the Mother's desired full FC +handset, but actually even worse than the same FreeCalypso Lite firmware running +on Motorola C139! Therefore, even though the Pirelli phone serves as the +Mother's inspiration for our own FC handset hardware, the existing Pirelli +hardware is mostly useless for the purpose of turning it into a libre phone - +all because of the vast amount of completely undocumented hardware in this +model. + +4.3. How to make it happen + +The main reason why a practically usable FC firmware version for Mot C139 has +not been produced yet is because I, Mother Mychaela, am not willing to do it in +such a way that would jeopardize my primary goal of true FC handset hardware. +I am willing to support FreeCalypso Lite on C139 as a *side addition* to the +main FC handset hardware goal, but never as a replacement. + +Right now my next project goal is to build my desired Venus development board. +Once that board is built, we will be in a better position to whip our TI-based +FC handset firmware into shape. No, my priorities won't change, and my initial +work on the Venus platform will be on the bigcolor firmware configuration. +However, once FC Tourmaline bigcolor firmware runs on FC Venus in a satisfactory +manner, with audio mode conversion implemented but still using the Calypso +buzzer for ringing, then it may be a good time to bring the smallbw +configuration up to par. And once FC Tourmaline smallbw runs in an end-user- +acceptable manner on FC Venus, then it will be a slam dunk to move it to actual +C139 hardware. + +4.4. Functional scope limitations + +Because FC Lite on Mot C139 can only ever be a side project and can never be my +main goal, I have to put some strict limits on the amount of work I am going to +do in that direction: + +* The color capability of C139 physical LCD will not be used by FC Lite + firmware, instead the screen of FC-on-C139 will always be black&white. The + reason for this limitation is that displaying color on C139 would involve + actual work (a non-trivial amount of it) to create an entirely new "small + color" UI configuration (as opposed to the existing bigcolor and smallbw), + whereas the existing smallbw config is a freebie gift from TI. + +* No musical ringtones, just one extremely basic ringing sound - implementing + musical ringtones for the buzzer would be C139-specific work which is not + needed for the main goal of FC Libre Dumbphone, which will use Melody E1 + ringing instead. + +* No support for actual headsets in the headset jack! The headset jack on all + Mot C1xx phones serves a dual function, it is both an analog headset interface + and a digital interface for computer connection (UART at 2.8V logic levels), + and in FreeCalypso we absolutely require the computer interface function of + this jack - it is essential for development and debugging. Therefore, the + "ordinary end user" function of the headset jack is lost. + +In summary, FreeCalypso Lite on Motorola C139 will be an *extremely* basic and +"bare bones" phone - but the hope is that it would still be useful to some.