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Mychaela Falconia <falcon@freecalypso.org>
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1 TI's TCS211 firmware and its predecessors contain a flash-resident bootloader
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Mychaela Falconia <falcon@freecalypso.org>
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2 stage which we call FRBL. This FRBL implements not one but two different
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Mychaela Falconia <falcon@freecalypso.org>
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3 protocols for interrupting the normal fw boot process, downloading a code image
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Mychaela Falconia <falcon@freecalypso.org>
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4 into RAM and jumping to it; we call these two protocols FRBL1 and FRBL2. The
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Mychaela Falconia <falcon@freecalypso.org>
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5 reasons for this oddity are historical: the original FRBL (TI GSM bootloader or
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Mychaela Falconia <falcon@freecalypso.org>
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6 TI GSM monitor or whatever it was called officially) consisted of cmdboot.c,
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Mychaela Falconia <falcon@freecalypso.org>
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7 command.c, convert.c, optboot.c, serial.c and start.c source modules and
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Mychaela Falconia <falcon@freecalypso.org>
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8 implemented the protocol we call FRBL1, then came MMJ and other TIDK people
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Mychaela Falconia <falcon@freecalypso.org>
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9 with their new FLUID idea, they decided on a different protocol which we call
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Mychaela Falconia <falcon@freecalypso.org>
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10 FRBL2, and they jerry-rigged their new FLUID bootloader into the firmware's
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Mychaela Falconia <falcon@freecalypso.org>
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11 FRBL code.
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Mychaela Falconia <falcon@freecalypso.org>
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12
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Mychaela Falconia <falcon@freecalypso.org>
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13 The original source for FRBL1 C modules appears to have been lost (it is not
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Mychaela Falconia <falcon@freecalypso.org>
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14 present in what we presume to be the world's last surviving copy of TCS211 from
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Mychaela Falconia <falcon@freecalypso.org>
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15 OM), all we have are COFF objects from TI-OM's 20070608 build. The reconst
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Mychaela Falconia <falcon@freecalypso.org>
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16 subdirectory contains our reconstruction attempt; this reconstruction is of
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Mychaela Falconia <falcon@freecalypso.org>
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17 poor quality because these particular COFF objects have only minimal symbolic
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Mychaela Falconia <falcon@freecalypso.org>
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18 information required for linking, as opposed to the much richer -g kind we got
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Mychaela Falconia <falcon@freecalypso.org>
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19 for L1 and GPF.
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Mychaela Falconia <falcon@freecalypso.org>
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20
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Mychaela Falconia <falcon@freecalypso.org>
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21 The test subdirectory is intended to contain our frbl1test and frbl2test
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Mychaela Falconia <falcon@freecalypso.org>
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22 programs; only frbl2test has been written so far.
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Mychaela Falconia <falcon@freecalypso.org>
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23
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Mychaela Falconia <falcon@freecalypso.org>
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24 Aside from implementing two different serial protocols, TI's FRBL as featured
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Mychaela Falconia <falcon@freecalypso.org>
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25 in their Calypso firmwares has one other major quirk: both FRBL1 and FRBL2 were
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Mychaela Falconia <falcon@freecalypso.org>
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26 implemented on 13 MHz platforms (the original purpose was to facilitate fw
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Mychaela Falconia <falcon@freecalypso.org>
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27 loading on TI's earlier DBB chips before Calypso that didn't have the boot ROM
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Mychaela Falconia <falcon@freecalypso.org>
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28 which we are so used to), on TI's D-Sample board (Calypso chip, 13 MHz CLKTCXO
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Mychaela Falconia <falcon@freecalypso.org>
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29 input) both the old way (fluid -oO via FRBL or via JTAG) and the new way
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Mychaela Falconia <falcon@freecalypso.org>
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30 (fluid -oo via the boot ROM) work well, but FRBL was never updated for 26 MHz
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Mychaela Falconia <falcon@freecalypso.org>
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31 platforms, thus on all practical Calypso platforms (Leonardo derivatives) one
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Mychaela Falconia <falcon@freecalypso.org>
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32 must use the boot ROM, not FRBL.
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Mychaela Falconia <falcon@freecalypso.org>
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33
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Mychaela Falconia <falcon@freecalypso.org>
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34 TI's TCS211 builds for Leonardo and all vendor firmwares (Openmoko etc) derived
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Mychaela Falconia <falcon@freecalypso.org>
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35 from this reference do include FRBL which was never updated for 26 MHz CLKTCXO
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Mychaela Falconia <falcon@freecalypso.org>
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36 input on these platforms. The result is that FRBL will only work if you talk
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Mychaela Falconia <falcon@freecalypso.org>
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37 to it at 230400 baud instead of TI's intended 115200 baud. TI's official
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Mychaela Falconia <falcon@freecalypso.org>
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38 version of FLUID does not support FRBL entry at 230400 baud and such operation
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Mychaela Falconia <falcon@freecalypso.org>
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39 was clearly never intended or officially supported - instead the officially
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Mychaela Falconia <falcon@freecalypso.org>
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40 supported way for Leonardo and Leonardo-based customer designs was to use
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Mychaela Falconia <falcon@freecalypso.org>
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41 fluid -oo mode, which works through the boot ROM just like fc-loadtool.
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Mychaela Falconia <falcon@freecalypso.org>
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42 However, there is a possibility that Openmoko may have tried to turn this FRBL
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Mychaela Falconia <falcon@freecalypso.org>
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43 bug into a feature - we are still investigating.
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