Regarding the cable from Dealextreme

Dieter Spaar spaar at
Thu Mar 18 07:52:15 UTC 2010

Hello Lubomir,

On Thu, 18 Mar 2010 01:00:44 +0100, "Lubomir Schmidt" <gentoo.lubomir at> wrote:
> How can i change the cable to get it working? What is a
> level-converter and where can i get such?

The level of the RS-232 interface is specified to be -3V..-15V for a
logic one and +3V..+15V for a logic zero, typically -12V and +12V is
used. The phone uses 0V and 3.2V. So you need a level-converter between
the RS-232 port of a PC and the phone.

The simple solution is to use a ready-made data cable with a built-in
level-converter, they cost around 9.00 EUR on ebay Germany including
shipping, either as USB or RS-232 variant. If you really want to build
your own level-converter, you can for example use the MAX232 IC. The
MAX232 is for TTL level (0V and 5V), I think there is a variant for
3.2V available, however I am not 100% sure.

Best regards,
Dieter Spaar, Germany                           spaar at

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