I have a brand new UNO; upload a few sketches and all works fine.
Then I uploaded the DataLogger example from the Arduino0022 collection without editing. This was a big mistake. This example keeps the serial port so busy on my system that it prevents the uploader from working. I had run into this sort of thing before, and at that time following the advice to press the reset button during the upload resolved the issue.
However this time I tried many times (~50) to upload using this technique and it failed. My ttyACM0 (specified in arduino defaults file) would often disappear and not reappear on reset. Arduino software was sluggish and would not respond until after an unusual delay.
The procedure I followed this time was:
- unplug UNO from USB
- shut down all instances of Arduino GUI
- start arduino GUI
- load intended sketch
- verify sketch compiles
- press upload
- wait 5 seconds
- plug in Arduino USB
- upload succeeded.
This may be of interest to others, including me when I fall into the same trap again. Any point in changing the otherwise excellent example to be more upload friendly, or is this problem unique to my situation?