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jcrm
09-06-2007, 09:02 PM
Hi guys,
Congrats on the 20 years! Im new at this and I have a question. I need to connect the propeller with the Aerocomm ConnexLink (RS232). Can I use the circuit shown in the figure in the attachment or do I have to make some type of modification?

Thanks,
Juan Ramirez

deSilva
09-07-2007, 12:14 AM
Whatever that device you are talking about ever be, this is not the best possible interface to it.

(1) By all means leave out the reset-connection!

(2) The 4,7k resistor would function as a "pull-down" to something as -12V so far as it is available on the DTR pin. This is usual but not mandatory. Your voltage swing for sending from the prop wil be -12 <-> +3 V

(3) Either your device will accept 0 <-> 5V, then you do not need -12 V or it will have a standard -12 <-> +12 V voltage, in that case you should protect the transistor basis against the incoming -12 V using a diode e.g..


I know a MAX 233 chip costs around $5 but it will relieve you from any further considerations without any additional part at all.

Leon
09-07-2007, 12:16 AM
You might need true RS-232 levels, especially if you don't have the DTR signal available on a PC serial port to give you a negative supply.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Post Edited (Leon) : 9/6/2007 5:21:49 PM GMT

Paul Baker
09-07-2007, 12:23 AM
Juan what is your intent with the Aerocomm, to provide a wireless serial link, or to program the Propeller?

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Paul Baker (mailto:pbaker@parallax.com)
Propeller Applications Engineer
[/url][url=http://www.parallax.com] (http://www.parallax.com)
Parallax, Inc. (http://www.parallax.com)

jcrm
09-07-2007, 04:36 AM
Thanks DeSilva ,Leon and Paul
I need one wireless serial link propeller and AeroComm ConnexLink

Amateur radio callsign: YV3FHR

Paul Baker
09-07-2007, 04:47 AM
In that case DTR isn't needed.

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Paul Baker (mailto:pbaker@parallax.com)
Propeller Applications Engineer
[/url][url=http://www.parallax.com] (http://www.parallax.com)
Parallax, Inc. (http://www.parallax.com)

jcrm
09-07-2007, 05:41 AM
Thanks again Paul

Juan Ramirez
Amateur radio callsign: YV3FHR

ALIBE
09-07-2007, 07:45 PM
i have been interfacing Propeller w/ Aerocomm AC4790 R/Tx for my robot project. Purely for communication btwn the robot and the homebase.

http://aliben.wordpress.com/2006/10/24/interfacing-aerocomm-ac4790-with-propeller-chip/
http://aliben.wordpress.com/2006/10/26/testing-the-ac4790-and-propeller-interface-w-alibe-homebase-command-center/
http://aliben.wordpress.com/2006/10/24/aerocomm-ac4790-a-short-introduction/



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"any small object, accidentally dropped, goes and hides behind a larger object."


ALIBE - Artificial LIfe BEing (http://aliben.wordpress.com/). In search of building autonoumous land robot