UART use with a TTL signal

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1

Hi,

I'd like to monitor my electric meter with a beaglebone.
I live in France where the electric meter deliver a signal that need
to be transform.
I see some adapters (RS232 or USB) on the web : http://teleinfo.dauguet.net/articles.php?pg=44
for example.
One of these adapters tranform a TTL signal to RS232.
If i want to user this one, I need to re-Transform the signal from
RS232 to TTL 3,3V for the beaglebone.
I think this is possible but the "double transformation" seems
useless.

I found a schema that show how to transform the "teleinfo" signal to
TTL level : http://vesta.homelinux.free.fr/site/wiki/teleinfo_sch.png
This one give a 5V TTL level where the beaglebone seems to need 3,3 V.

My question is : Can I use these shema or not to create a custom
adapter ?

PS : I have no electronics knowledge and can't design such adapter.

Laurent

2

Sparkfun.com sells a RS232 Shifter SMD, PRT-00449, that converts from 2.8, 3.3 or 5v to rs232.

wjr

3

You need to use a level shifter. Try this one:

http://www.sparkfun.com/products/8745

4

Thanks for your responses.
The level shifter seems to be a solution ... for a very low price.

Laurent