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Yes, the signal is being inverted, but it requires external circuitry, as described above.  

I'm just saying that it would be nice if we could eliminate some of the circuitry, make converting from rs232 to ttl simpler.  

I mean, if we can eliminate the external not gate, then that would mean you could convert a 5v rs-232 signal to ttl using only a diode and a resistor.  Or, maybe even eliminate those as well, since the arduino already has something built in to eliminate negative voltages. 
« Last Edit: October 15, 2011, 04:57:18 pm by CompWiz17 » Logged

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I mean, if we can eliminate the external not gate, then that would mean you could convert a 5v rs-232 signal to ttl using only a diode and a resistor.

If you look at the below, I inverted 12v rs232 to 5v TTL just using two resistors and a transistor from Radio Shack. Some times it is easier to just do it and move on.

http://arduino.cc/forum/index.php/topic,74650.msg562845.html#msg562845
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Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   smiley-cool

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So,just for fun...what was the solution to the original question here??? smiley
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Well, as I described in the thread, an RS-232 signal can be converted to TTL serial(which the arduino can read) using a simple circuit.  That is, a diode and pull-down resistor to convert the -5V signal to 0v, then a not gate to invert the signal. 

We used this circuit successfully in the Space Balloon we launched, years ago. 

Was there something else you were wondering about? 
« Last Edit: June 09, 2014, 01:55:51 pm by CompWiz17 » Logged

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No,just seemed like a question that could have been answered long before talking about servos and card readers...lol.
Hard to find solutions on forums nowadays without going through endless non related topics.
Thanks for the reply.
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