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Topic: Stupid question from a old time programmer....new arduino user (Read 471 times) previous topic - next topic


I have searched around but don't seem to be able to find an answer.  This is such a beginner's question I hate to ask.

I just hooked up a UNO and got the blink code loaded and running.  I was able to modify it and upload it multiple times, no problem. 

I loaded the demo code for a servo and ran it with no problems.  The problem now is that I want to go back to a "blink" program and it will not upload the code.  It gives me a banner that the com5 port is not available.  Manager shows the port is fine.  It looks like the code that is running is keeping the upload from happening.  Port 5 is the correct port. 

Being a programmer, but being new to the development system, I have tried all the normal things.  I hit the reset button, but the processor seems to simply start running the same code.  I tried holding down the reset while trying an upload.  No luck.

Can someone tell me the magic incantation to get different code uploaded.  I must be missing something.

Window 7 64bit.  UNO R3 reference board design with a Atmega328p-pu  1.0.1

Nick Gammon

Try unplugging it (from the USB). Also disconnect anything else connected. Hold down reset and plug the USB back in (keeping Reset held down). Start uploading the sketch. When it says "uploading" release Reset.

However if it says COM5 is not available you have other issues. I suggest the Loopback test stickied at the start of the Installation and Troubleshooting section.


Tried that.  No luck.  The message is
Serial port 'COM5' not found.  Did you select the right one from the
Tools>Serial Port menu?

When I go to the Tools pull down menu, the Serial Port selection
is grey'd out.
I will keep looking.  Thanks for the reply.


I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.


Just finished.  With the board in reset and a loopback installed, I was able to do a com session on port 5 and got an echo of the data sent.

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