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−Sony Ericsson J100 target support in FreeCalypso
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−================================================
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−
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−SE J100 is the last Calypso device target of OsmocomBB origin to be added to
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−FreeCalypso, joining the already-supported Mot C1xx and Pirelli DP-L10.  This
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−target is really not interesting at all on its own merit, instead it has been
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−added to FC Magnetite for testing purposes: to verify that we are able to drive
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−this J100 variant of Compal's RFFE and produce correct RF Tx output as observed
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−with our CMU200 instrument.
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−
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−Despite being a Sony Ericsson rather than Motorola product (slightly different
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−case design, totally different battery and accessory connectors), in core
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−technical terms this SE J100 phone is still Compal, same as Mot C1xx.  It is
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−technically closest to Mot C139, with only a few differences:
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−
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−* The display is different: same 96x64 pixel color, but a different model
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−  requiring a different driver;
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−
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−* A ringtone player chip is used instead of the Calypso-driven buzzer;
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−
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−* There are a few differences in GPIO setup, in TSPACT signal usage for RF Tx
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−  and in some RF Tx parameters (APC offset and Tx ramp templates) stemming from
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−  the use of a slightly newer RF PA, such that a firmware image built for Mot
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−  C139 or C11x should not be run on the J100, even if the LCD and the buzzer
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−  are don't-cares.
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−
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−If you have one of these phones and wish to run FreeCalypso on it, follow the
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−procedure for Mot C139 in C1xx-Howto, with the following differences:
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−
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−* You need to build a firmware image specifically for the j100 target
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−  (./configure.sh j100 hybrid-vpm), don't flash a c139 or c11x build.
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−
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−* Only the VPM configuration is available, not the proof-of-concept UI - the
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−  LCD driver for the latter configuration exists only for the Mot C139 LCD,
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−  not for SE J100 or any other C1xx.
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−
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−* It is not certain at all whether the battery charging configuration we have
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−  for Mot C1xx is correct or not for SE J100 - see further below.
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−
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−Serial connection difficulty
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−============================
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−
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−Connecting the serial interface (the obvious prerequisite before one can do any
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−kind of firmware hacking) is a lot more difficult on the SE J100 compared to
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−Mot C1xx.  Following Sony Ericsson's product line, this J100 phone does not have
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−round-jack headset or charger connectors, instead all accessories (charger,
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−headsets, Calypso UART access) are connected through a multi-pin connector (12
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−pins to be exact) that was used by SE across their product line.  While there
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−exist a number of "cottage industry" vendors who make ready-to-use serial cables
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−for the kind of headset jack found in Mot C1xx phones, there does not appear to
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−be anyone making comparable cables for SE J100, thus the only way to play with
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−one of these phones is to construct the necessary serial cable yourself.
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−
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−The pins on SE's proprietary accessory connector which carry Calypso UART RxD
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−and TxD on the J100 are the same pins which carry USB data lines on some other
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−SE phones which (unlike J100) have an official data services / computer
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−connection function, thus there are two ways to hack together Calypso UART
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−access on the J100:
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−
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−Option 1: you can take a Sony Ericsson (or clone) USB-to-phone data cable and
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−mutilate it: cut off the USB end, split out the little wires and solder them to
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−your choice of 3.3 V USB-serial adapter.  This is the route that was taken by
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−this author (Mother Mychaela), and when I did it, I ran into a nasty little
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−problem: the wires inside the cut-apart SE-clone USB-to-phone cable are
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−extremely thin (can't be any thicker than 28 AWG, and seemed to be even thinner
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−than that), and the solder contraption feels like it is barely holding, like it
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−is going to fall apart at any moment.
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−
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−Option 2: you can take the same SE (or clone) USB-to-phone data cable, but
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−instead of mutilating it, connect it to another custom contraption: if you can
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−find a USB female-A connector part to which you can solder your own wires (or
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−cut apart some other cable that terminates in a USB female-A socket), make a
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−cable contraption consisting of this USB female-A on one side (into which you
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−insert the unmodified SE cable) and your choice of 3.3 V USB-serial adapter on
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−the other end.  I still have one more SE-clone data cable which I haven't cut,
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−so I might try this approach.
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−
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−For your choice of 3.3 V USB-serial adapter, you should definitely pick either
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−FT232R or CP2102, so you can use GSM-specific high baud rates (GSM-specific
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−because they derive from the 13 MHz clock) to transfer flash dumps and firmware
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−images.
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−
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−Battery charging problem
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−========================
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−
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−Another problem stemming directly from SE's accessory connector arrangement is
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−that it is very difficult to connect both a charging power source and Calypso
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−UART access at the same time.  At first I thought it was completely impossible
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−(there is only one accessory connector on the bottom of the phone), but then by
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−pure luck I acquired an unusual kind of SE charging adapter: this rare adapter
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−has a pass-through mechanical design, such that one can plug this charging
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−adapter into the phone and then piggy-back another accessory into it!  However,
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−this kind of SE charging adapter is super-rare, and I haven't played with mine
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−yet because it has Europlug pins (not USA plug) on the AC power end, and I
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−haven't got around yet to acquiring the requisite AC plug adapter.
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−
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−Connecting both the charging power source and the Calypso UART at the same time
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−is important for two reasons:
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−
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−1) For me as the FreeCalypso developer, that is the only way I can develop and
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−test the charging configuration for this phone model.
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−
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−2) For "end users" of the voice pseudo-modem FreeCalypso fw configuration on
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−this target, if you have no serial connection, you have no way of seeing how
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−your charging progresses, as there is no LCD driver and the display stays dark
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−and non-functional.
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−
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−Because we don't have working battery charging on this SE J100 target yet, the
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−only safe way to play with this target at the present moment is to have two of
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−these phones (or another phone of a different model that takes the same
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−batteries), and keep one phone fully intact with its original fw so it can be
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−used to charge batteries when the FC-converted phone runs its battery down.