Atmega328 Rainbowduino Programming via Arduino Issue

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ant9000
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Re: Atmega328 Rainbowduino Programming via Arduino Issue

Post by ant9000 » Wed Jan 12, 2011 6:50 am

michu wrote:thanks for this answer ant9000, I just added it to the wiki. what do you think happens with an arduino UNO - as this device uses a different bootloader is there a chance the firmware upload will work fine?
Honestly, I don't know :| I've only had one Arduino 2009 and one Rainbowduino to work with, so everything I've managed to understand was really grabbed from the 'net and then digested.

From what I read at http://arduino.cc/en/Main/ArduinoBoardUno (look for the paragraph Automatic Software Reset), it should be possible to disable the autoreset feature, I'd say that yes, you have chances.

As a matter of fact, reading on from the thread linked there, I've found this piece of advice:
FYI, I just tried another little experiment (modified)
I took a 110 ohm resistor and connected the arduino 5v pin to the reset pin, jumper style. They are close together.
Guess what? No more com port resets
Remove the jumper resistor and com port resets resume.
The 110 ohm resistor is just enough to keep the reset pin high (2.38v) when the ftdi chip tries to pull it low, and limits the current through the ftdi pins to 24ma*.
If it really works on the Uno, I'd venture to say that you could use _any_ Atmega 368 based Arduino as a real USB to serial converted by simply connecting RESET and 5V with a suitable resistor. To let the Rainbowduino enter flash mode, though, you won't be able to use the RESET signal taken from the Arduino any more. Hence, you have to resort to the trick of pressing the Rainbowduino reset button a few seconds after starting the upload in the IDE.

Apologies to Miso for letting you into buying a converter befor attempting this one ;-(

Antonio

miso
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Re: Atmega328 Rainbowduino Programming via Arduino Issue

Post by miso » Wed Jan 12, 2011 7:41 am

Hi Antonio.

No need to apologise, contrary thanks to the new info. The UARTSB device is a much straight forward way of doing it anyway. No faffing with resistors and reset buttons. It is a very small device as well. Smaller than my thumb.
I came across the resistor trick in the past but I could not remember where I read it.

M

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