USB Serial Com port mystery.. I have been playing with an arduino uno for awhile with no problems uploading sketches. Recently, I have been having problems with "losing" the assigned serial port. To correct it I have to usually shut down everything and/or plug the usb into a different physical jack and/or make changes in device manger, or all of the above on my laptop. HOWEVER, it does not happen at all when I use a mega board, and just occasionally when I use a nano.
Any ideas what's going on?
With that mass of a description it's hard to make analysis. As my UNO and my Mega don't show the same behavior, my guess is that you either have a bad solder point somewhere on your UNO or you messed up your Windows driver somehow.
waynek:
I have been having problems with "losing" the assigned serial port.
What do you mean by "losing" and "assigned"?
The uno and the mega have different serial port hardware, they may normally be assigned different com ports. Is windows xp your pc os?
zoomkat:
The uno and the mega have different serial port hardware, they may normally be assigned different com ports. Is windows xp your pc os?
What? The current Uno and mega board use the same USB serial converter chip. The assignment of a com port number is a function of the PC it was attached to for the very first time. You may have a Uno board that is assigned say com5 on your PC, but if you brought it over to my house and we plugged it into my PC for the first time it might assign it as com12.
At least that is how it all works on my Windows XP system.
Lefty
At one time xp had an issue where a USB serial adapter would be assigned an ever increasing com port number (the same USB adapter was not recognized as the same). A fix was to go into the advanced comport settings and assign the adapter to a known unused comport number. That fixed the changing com port number for that adapter.
What? The current Uno and mega board use the same USB serial converter chip.
This is only true if mega means Mega2560, the Arduino Mega (http://arduino.cc/en/Main/arduinoBoardMega) uses an FTDI chip for the USB2Serial conversion and so uses a different driver than the UNO.
The OP wasn't clear about which one he uses, so if we take him literally zoomkat was right with his finding.
pylon:
What? The current Uno and mega board use the same USB serial converter chip.
This is only true if mega means Mega2560, the Arduino Mega (http://arduino.cc/en/Main/arduinoBoardMega) uses an FTDI chip for the USB2Serial conversion and so uses a different driver than the UNO.
The OP wasn't clear about which one he uses, so if we take him literally zoomkat was right with his finding.
That is why I used the word 'current' in my statement. If you want to compare older boards then at one time the standard 328P based Duemilanove board and the then 1280P based mega board also used the same FTDI based USB serial chip. So trying to parse the statement:
The uno and the mega have different serial port hardware
To be other then a generally incorrect statement, and also with no bearing on what may or may not be the OP's problem is just an exercise in parsing for parsing sake.
Lefty
This has happened to me quite a few times and it seemed to be related to moments when I forget to connect my Arduino ground to my target ground, or when I power my target before connecting my arduino. I lose connection to the Arduino and have to unplug it for a short bit and plug it back in.
Probably tripping some current protection mechanism.
Not sure if this is your problem, but that is my similar experience.