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Author Topic: Arduino Standalone RS232 Communication  (Read 344 times)
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 Bigger Bigger  Smaller Smaller  Reset Reset

Hi,
I have soldered a standalone arduino on a custom pcb and  Ihave some problems with programming the Arduino by the IDE over a RS232 connection. I soldered the microcontroller to the dsub connector as shown as in this picture :
 http://www.hobbytronics.co.uk/image/data/tutorial/arduino-hardcore/arduino-hardcore-schematic_2.jpg
[note : I had nothig connected to the reset pin of the microcontroller]
When I tried to load a sketch on the microcontroller, it did not work. I found out later that I have to reset the microcontroller right before the IDE starts to send data to the microcontroller. I tried to do this with a BC548 transistor hooked up to the DTR signal from the RS232 which switches the reset pin to ground when DTR is high, but it didn't work too smiley-roll-blue
Schematic of my failed DTR reset circuit :

I hope someone can help me with this reset-problem  smiley
« Last Edit: October 10, 2013, 01:53:03 pm by Me262 » Logged

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 Bigger Bigger  Smaller Smaller  Reset Reset

DTR is created as a level. You need to turn it into a pulse.
Run it thru a 0.1uF (100nF) cap to the reset pin, reset pin needs a 10K pullup resistor.
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Thanks! Going to try it tomorrow.
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 Bigger Bigger  Smaller Smaller  Reset Reset

Put the capacitor in series with the 4k7 R1 in the present circuit.  Done!
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The caps were delivered today. Connected them in series to R1 an it worked perfectly , Thanks!  smiley-cool
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