I just got my Arduino Uno two days ago and I wanted to be familiar with it. I ran the blink sketch and it worked fine. Then I burnt the Digital serial read program and it didn’t work as expected. So I tried to burn another program. But, the problem is that I am not able to do that now. The Tx LED is always ON. When I plug the board my USB port is shown in the list ( /dev/ttyACM0), but when I start uploading the sketch a message is shown ```
Serial port /dev/ttyACM0 not found
Although I removed my bluetooth dongle(suggested on Arduino site) and a package called “BRLTTY”(suggested on ladyada.net) to get it working again and that also after many tries. After I uploaded blink sketch everything is working fine. I suspect the problem was with the Serial communication because now I am using bluetooth again and still am able to upload sketches.
This is a bug in the Arduino firmware. I found a forum thread which gives a link to a patch for this problem. People who run into the same problem as mine can have a look at post #34
I just bought my first real Uno, MicroCenter Sparkfun product, and have the same problem. Unplug USB and replug USB, the port will reappear though one number higher. Any upload attempt fails with “processing.app.SerialException: Error opening serial port ‘/dev/ttyACM3’”. I notice that uploads succeed normally though if run as root. ttyACMx has the same permissions as ttyUSBx on an Adafruit FTDI Friend