TX stuck ON, serial port greyed out

I am a newby, and I have an Uno, running Arduino 0021 on Ubuntu 10.10.

It worked fine running the example "Blink" and some simple variations (I could change the blink times, so I know code was uploading), but after I uploaded the example "DigitalReadSerial" the TX LED always on. Pushing the reset button causes the "L" LED to briefly flash, but the TX light stays on any time power is applied. The RX LED does not come on.

When I try to open the serial connection or upload I get a message "Serial port '/dev/ttyACM0' not found. Did you select the right one from Tools > Serial Port menu?" When I look in the Tools menu, the Serial Port selection is greyed out.

I rebooted my PC, but that didn't fix things. I also tried a different USB port, but no difference.

Any ideas on what is wrong, or how to fix it?

Here are a few port diagnostics (I have no idea what they mean):

[ 9207.864066] usb 3-1: new full speed USB device using ohci_hcd and address 11 [ 9208.035283] cdc_acm 3-1:1.0: ttyACM0: USB ACM device [ 9531.385921] usb 3-1: USB disconnect, address 11 [ 9534.844066] usb 3-1: new full speed USB device using ohci_hcd and address 12 [ 9535.015263] cdc_acm 3-1:1.0: ttyACM0: USB ACM device [ 9538.672232] usb 3-1: USB disconnect, address 12 [ 9543.076082] usb 3-1: new full speed USB device using ohci_hcd and address 13 [ 9543.255274] cdc_acm 3-1:1.0: ttyACM0: USB ACM device [10565.508798] usb 3-1: USB disconnect, address 13 [10569.244073] usb 3-1: new full speed USB device using ohci_hcd and address 14 [10569.415289] cdc_acm 3-1:1.0: ttyACM0: USB ACM device don@Ubuntu:~$ ls -l /dev/ttyACM0 crw-rw---- 1 root dialout 166, 0 2010-11-15 19:16 /dev/ttyACM0

Two possible causes:- 1) The USB chip on the arduino is broken - get another arduino. 2) Something has gone wrong with the drivers - uninstall them and install them again.

Hi,

The same problem over here, I have an uno on ubuntu 10.10 and if i want to use serialcommunication in a sketch, the Tx-led turns on after upload and i can't upload code anymore.(the line is busy)

You can solve this with unplugging the board, press the resetbutton and hold it pressed, plug the board in again and when you press upload on your computer release the resetbutton, (using a program without serialcomm.)

greetings, Chris

I was going to suggestion the same procedure as Chris4. Unpower the board, hold reset, and then attach to PC. (This is not the same as just pressing the reset button. You must hold the board in reset through power-up.)

The RESET button holds the ATmega328 (Microcontroller) in Reset but has no effect on the ATMega8U2 (USB-to-serial interface). Based on the original description, it sounds like the ATmega328 starts communicating with the ATMega8U2 and puts the ATMega8U2 into an unknown state. By holding the ATmega328 in RESET, it gives the ATMega8U2 a chance to initialize.

I 'm really frustrated about this, I want to Use the serial comm. to follow the program on the computer screen but it doesn't work on ubuntu 10.10

Is this a hardware problem, I thought that there are no drivers needed with the uno.

Chris

I reloaded Arduino 0021, didn’t change anything.

Thanks for the ideas, but no luck so far.

I tried the suggestion to hold down the RESET button during power up. The TX LED is now off, and the L LED is flashing in a quick pattern. However, the Tools > Serial Port selection is still greyed out, and I can’t upload anything.

I will try installing Arduino 0021 on a different, Windows machine and try again (to see is a different USB port and OS make any difference), but that may take a while…

My typical error message:

Binary sketch size: 962 bytes (of a 32256 byte maximum)
processing.app.SerialException: Serial port ‘/dev/ttyACM0’ not found. Did you select the right one from the Tools > Serial Port menu?
at processing.app.Serial.(Unknown Source)
at processing.app.Serial.(Unknown Source)
at processing.app.debug.Uploader.flushSerialBuffer(Unknown Source)
at processing.app.debug.AvrdudeUploader.uploadViaBootloader(Unknown Source)
at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(Unknown Source)
at processing.app.Sketch.upload(Unknown Source)
at processing.app.Sketch.exportApplet(Unknown Source)
at processing.app.Sketch.exportApplet(Unknown Source)
at processing.app.Editor$DefaultExportHandler.run(Unknown Source)
at java.lang.Thread.run(Thread.java:636)
processing.app.debug.RunnerException: Serial port ‘/dev/ttyACM0’ not found. Did you select the right one from the Tools > Serial Port menu?
at processing.app.debug.Uploader.flushSerialBuffer(Unknown Source)
at processing.app.debug.AvrdudeUploader.uploadViaBootloader(Unknown Source)
at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(Unknown Source)
at processing.app.Sketch.upload(Unknown Source)
at processing.app.Sketch.exportApplet(Unknown Source)
at processing.app.Sketch.exportApplet(Unknown Source)
at processing.app.Editor$DefaultExportHandler.run(Unknown Source)
at java.lang.Thread.run(Thread.java:636)

OK, the UNO now works with Arduino 0021 on a Windows 7 machine. It does not work on the Ubuntu 10.10 machine. Why it worked for a while on the Ubuntu but then stopped is a mystery to me. I will try re-installing Arduino 0021 once more.

If that doesn't work, I will have to either re-install Windows on my machine, or negotiate with my kids for time on their Windows machine (and there are challenges to either choice...)

Reinstalled Arduino 0021 on Ubuntu 10.10. UNO does not upload.

I guess it is back to Windows, at least for Arduino

Hello,

I [mistakenly] believe I've solved this very frustrating problem, at least with ye olde Ubuntu 10.4: brltty must be uninstalled as follows:

sudo apt-get remove brltty

I performed a superstitious reboot afterwards

The requirement to uninstall brltty is mentioned in the quickstart guide, and perhaps like youse I neglected this step. I also ran the LEDs tutorial, changed the number of LEDs, etc, and then hit a brick wall when I ran the AnalogReadSerial example. After removing brltty I can now again upload programs to my Arduino.

~K

[ UPDATE... To my great disappointment, loading AnalogReadSerial again caused the USB connection to lock up again. Various combinations of rebooting, restarting Sketchbook, and resetting Arduino w/out power connected did not rectify. Guess I'll try it on MS Windows now. ]

I also tried removing brltty- I had no improvement

I was having similar problems, and this worked for me: from: hoos (dot) net /site/ubuntu/solved-problem-with-arduino-serial-communication-on-lucid-lynx-arduino-0021/

If you have Arduino Uno or other similar board and experiencing problem with serial communication on Ubuntu 10.04 and Arduino 0021, this is how you can fix it. Problem occurs when serial communication is started (streaming values). Board after that lock up and Arduino software becomes very unresponsive. Fix is this, add delay after initializing serial communication in setup part:

void setup() {
  Serial.begin(9600);
  delay(1000);  // 1sec is enough
  // other setup stuff
}

That's it! Arduino after that function properly and you can communicate with board.

If you have Arduino Uno or other similar board and experiencing problem with serial communication on Ubuntu 10.04 and Arduino 0021, this is how you can fix it. Problem occurs when serial communication is started (streaming values). Board after that lock up and Arduino software becomes very unresponsive. Fix is this, add delay after initializing serial communication in setup part: Code:

void setup() { Serial.begin(9600); delay(1000); // 1sec is enough // other setup stuff }

Setup is read only once, this does not work.

greetings Chris

...or sortof. I could listen to the first code I put on there, but now I can't upload new code to it.

Setup is read only once, this does not work.

Setup is executed every time the Arduino resets. If the issue with uploading code to the UNO is that a constant stream of serial output prevents the booloader from getting a word in edgewise, then this will help. In a typical application, a 1 second delay in setup() is not going to be a big deal.

There's a small problem with the 8U2 firmware acting as the usb-serial convertor on the Uno. We're in the process of releasing a fixed version, which you'll be able to upload to the Uno without any additional hardware.

Thanks mellis for pointing that there's something wrong with it. Could you point us to any discussion on this bug so that we can follow it? I could also be able to help testing it as I'm stuck with a nice fixed TX on on my today bought arduino uno.

having the same problem. ubuntu 10.10. I finally managed to get a non Serial sketch uploaded. I have no idea if the sequence matters, but here is what I did:

  1. Unplug arduino
  2. Change board type in arduino program to arduino FIO
  3. Quit arduino program on computer
  4. hold reset while plugging back in (L flashes continually)
  5. restart arduino
  6. Serial port is now an option, correct port selected, write non serial sketch, and change back to arduino uno
  7. upload

  8. never upload another serial sketch till there is a fix for this bug. Which is seriously limiting.

There is a new firmware available for the 8U2 which cured my serial problems. Instructions for upgrading using Ubuntu are here :

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1286088093/30

Start at stimmer's post #34

I had the same problem on a Mega 2560 using Arduino 0021 on Ubuntu 10.04. Other solutions to get it responding didn't work for me.

(Temporary) Fix for getting it out of the broken state: 1. Plug in Arduino. 2. Open Arduino software. 3. Pick an example sketch that doesn't use serial (like an LED blinker). 4. Make sure board type, etc, are correct. (Be patient when opening the Tools menu) 5. Open Serial Monitor. 6. Change baud rate (to anything). (Notice the TX light flickers) 7. Quickly hit upload. If the upload succedded, then enjoy. If it didn't, go back to step 6. (Try changing between a couple of baud rates, then hit upload.) I got it on the 2nd try.

I've been able to follow pluggy solution above and I'm now able to use my UNO on Archlinux without any problems.