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Topic: IDE 1.0.4: Serial Port Problem (Read 1 time) previous topic - next topic


I have been building applications on a Mega2560 for a couple of years, and I have never seen the USB com port thing work smoothly for long. If I use the serial monitor feature, it hangs about 25% of the time, after about a page of output. Then I cannot reload a sketch ( " Serial port COMx not found") even though the XP Device Manager shows the Mega on the correct COM port. Usually I disconnect the USB cable a couple of times and the COM port reappears in the IDE Tools menu, and I am good to go. This has become a habit and the inconvenience is only intermittent, so I have lived with it. Changing USB cables, re-installing drivers, restarting the IDE does not help.

I have just installed version 1.0.4 of the IDE and the problem has become worse. Now any use of the Serial Monitor causes the COM port to disappear from the IDE Tools menu, and it stays gone until I cycle the power on the PC. Very inconvenient.

There must be hundreds of posts on forums about the IDE and missing COM ports, but they don't get me closer to understanding the problem. Now that it has become worse with the new version of the IDE, I am beginning to suspect it may be, at least in part, an Arduino IDE problem.

Anybody have any insight into this? Is there a simple way to recover the COM port? A patch or workaround for the IDE?

I have no other applications that I know of that access the COM port. Re-assigning or disabling/enabling the COM port does not recover it. Always, the Device Manager shows the correct COM port assigned to the Mega.


Right after I posted, I just had a thought. It may be that the use of the serial monitor feature is sensitive to voltage levels on the Arduino. If I am playing with an application that drawing some 5v current ( say an expansion board or shield), could this be causing the IDE to drop the COM port? I don't see any other signs of low power in my apps, but maybe the port dropping is the first indication.

It would explain why the problem is intermittent. I'd like to do a test to see if the power consumption goes up or the voltage drops when the serial monitor is invoked. I think I have only seen the problem when I am powering everything from the USB cable. More experimenting is in order, to see running on an external 9V source cures the problem.


I had some issues with my mega 2560, in fact I added a "fix" in http://arduino.cc/forum/index.php/topic,118440.0.html when the serial port stop responding because I was tired of doing that manually. After all, it was something with the avrdude/winavr original IDE has. Maybe my modded version solves your problems too
My website: http://ried.cl

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