hmm, sorry, data cable question

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hmm, sorry, data cable question

labad jala
Hello techies!
I am new to the list and I acquired a c139. I'd like to buy a rs232/jack 2,5mm named t191 flash (and not unlock) cable. They look 100% the same (even stickers). Is this important? I understand that I have also to use a rs232/usb adapter. The one I have (U232P9 with link/tx/rx leds) gives +/-9,4 v. So my concern is to not fry the Moto..Any advise welcome.

Cheers.
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Re: hmm, sorry, data cable question

tsaitgaist
hi,

please read the wiki : http://bb.osmocom.org/trac/wiki/CalypsoSerialCable
-> only use 3.3V

kevin

On 04.02.2011 00:47, labad jala wrote:
> Hello techies!
> I am new to the list and I acquired a c139. I'd like to buy a rs232/jack
> 2,5mm named t191 flash (and not unlock) cable. They look 100% the same
> (even stickers). Is this important? I understand that I have also to use
> a rs232/usb adapter. The one I have (U232P9 with link/tx/rx leds) gives
> +/-9,4 v. So my concern is to not fry the Moto..Any advise welcome.
>
> Cheers.

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Re: hmm, sorry, data cable question

Harald Welte-3
In reply to this post by labad jala
On Fri, Feb 04, 2011 at 12:47:50AM +0100, labad jala wrote:

> I am new to the list and I acquired a c139. I'd like to buy a rs232/jack
> 2,5mm named t191 flash (and not unlock) cable. They look 100% the same (even
> stickers). Is this important? I understand that I have also to use a
> rs232/usb adapter. The one I have (U232P9 with link/tx/rx leds) gives +/-9,4
> v. So my concern is to not fry the Moto..Any advise welcome.

if you put a usb/rs232 converter and then a rs232/2.5mm cable behind each
other, there should be no problem, at least not voltage-wise.  The usb/rs232
converter cable with DB-9 will up-convert to +/- 9V, and the T191 cable
with DB-9 will then down-convert again to 3.3V

In case of any doubt, simply use a multimeter to verify.  RS323 is low-active,
i.e. in idle state the lines are at their highest voltage.

Regards,
        Harald
--
- Harald Welte <[hidden email]>           http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)

Roy
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Re: hmm, sorry, data cable question

Roy
This post was updated on .
I made this interface and it is 100% working!

[Removed]

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Re: hmm, sorry, data cable question

wpatan
Please double check if your cable's output is 3.3v... this circuit could fry your phone.
The output of MAX232 should not exceed 3.3v
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Re: hmm, sorry, data cable question

Lokkju Brennr
With a 7805 and max232, it looks like it is probably 5v (the circuit
is using the R2OUT/T2IN pins, which are Vcc, so 5v).  A MAX3232 with
something like a LM2940-3.3 would probably be a *much* better option,
and give you real 3.3v.

Loki

On Fri, May 20, 2011 at 7:43 AM, wpatan <[hidden email]> wrote:

> Please double check if your cable's output is 3.3v... this circuit could fry
> your phone.
> The output of MAX232 should not exceed 3.3v
>
>
> --
> View this message in context: http://baseband-devel.722152.n3.nabble.com/hmm-sorry-data-cable-question-tp2419703p2965845.html
> Sent from the baseband-devel mailing list archive at Nabble.com.
>
>

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Re: hmm, sorry, data cable question

labad jala
In reply to this post by labad jala
Hi again techies.

Thanks for your advises and schemas. I already bought what was announced and illustrated as a mot t191 cable at a french company but it turned to be a "flash cable" with possibly wrong pinout and voltage. If you look at http://www.cellcorner.com/xshp/unlock-phone-codes/motorola-t190-t191-t193-unlock-data-cable.html, it's looks exactly the same one as I have. Did someone buy this one and used it successfully? I measured 4 volts when putting positive pin of my voltmeter to rx and negative pin on ground of the 2.5mm jack.. As said before, don't want to fry my moto. No cable, no project:( Sorry for my noobie question on this high level mailing list...
Roy
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Re: hmm, sorry, data cable question

Roy
In reply to this post by Lokkju Brennr
these are my voltage measurements

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Re: hmm, sorry, data cable question

n0p [Luis Bernal]
what serial port are you using?
usb-serial? a laptop one?

you are not frying your mobile only because you are lucky: your com port fails to deliver the 12~15v standard to the rs232 and delivers 5v instead

so the 7805 regulator fails to deliver 5v because it's a linear regulator with a high drop out (internal voltage loss- it is designed to work at at least 6 or 7v ) plus the diodes voltage drop and it's delivering 3.4v

if your connect that cable to a good com port, it will drive the calypso at 5v and it will fry it. right now is delivering 2.5v on tx, and it seems that's just enough to drive the calypso serial

TL;DR: get a usb->ttl3.3v cable and forget this one

also, did anyone tried attaching a phone to a 5v cable to see if it really dies?


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Re: hmm, sorry, data cable question

Sylvain Munaut
Hi,

> you are not frying your mobile only because you are lucky: your com port
> fails to deliver the 12~15v standard to the rs232 and delivers 5v instead
>
> so the 7805 regulator fails to deliver 5v because it's a linear regulator
> with a high drop out (internal voltage loss- it is designed to work at at
> least 6 or 7v ) plus the diodes voltage drop and it's delivering 3.4v

Yup exactly.


> if your connect that cable to a good com port, it will drive the calypso at
> 5v and it will fry it. right now is delivering 2.5v on tx, and it seems
> that's just enough to drive the calypso serial

Actually his cable is delivery the 3.4 V.

The 2.5V comes from the calypso because its serial port _is_ 2.5V and
not 3.3V. We use 3.3V converters because they are more common and work
fine, but it's still overdriving the calypso.

> also, did anyone tried attaching a phone to a 5v cable to see if it really
> dies?

It might not die right away, the ESD diodes will take some of it at
first ... but for how long is the question.
It also depends on the impedance of the driver, if you have a 1k
resistor on the path, it would help I guess.
But there is also the issue of the 2.5V from the calypso needs to be
detected as 1 by a 5V cable.


Cheers,

    Sylvain

Roy
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Re: hmm, sorry, data cable question

Roy
Ok thank you for your comments
I've inserted a zener diode between the ground and  Rx pin to reduce the tension.



Roy
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Re: hmm, sorry, data cable question

Roy
Just now I tested this interface with a Prolific USB cable and works well