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Serial Cable » History » Version 5

vogelchr, 02/19/2016 10:48 PM
Added hints and warnings.

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The Calypso phones typically all have a serial port @ 3.3V levels on the 2.5mm earphone jack.
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Those cables are sometimes called ''T191 unlock cable''.
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You can either buy ready-made cables, e.g. at:
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 * [https://www.akku-king.net/_py_Handyzubehoer-Datenkabel-USB-Motorola-USB-Datenkabel-fuer-Motorola-T191-C113-C113a-C114-C115-C115i-C116-C117-C118-C119-C121-C122-C123-C136-C139-C140-C155-C156/a-20104991/ akku-king.net]
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 * [http://www.dealextreme.com/details.dx/sku.14664 dealextreme.com] RS232, not USB variant
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Or you can build it yourself (detailed instructions can be found on the net, search for "t191 unlock cable" or the like).
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 * TxD is at the tip of the plug (PC to Device)
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 * RxD is at the middle contact (Device to PC)
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 * GND is the outer contact
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== Hints and Warnings ==
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 * If you don't use a 3.3V (low voltage TTL, LVCMOS) serial port you can fry your phone! (internally, it connects to the IO-pins of the baseband processor which run at 2.8V). '''Don't connect directly to your PCs serial port (running at +/- 12V!).'''
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 * If your development system is virtualized (runs inside VMware, Virtualbox, Parallels...) the connections can be unreliable (the loader protocol is timing critical).
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 * Your safest bet is a USB cable with a FTDI- or Prolific chip (FTx232, PL2303) configured for operation at 3.3V connected to a machine running Linux natively.
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