Lost /dev/ttyACM0

Development Tools IDE 1.x
1

Hi all,
I recently got myself an arduino uno (in an ardx-kit). And still in the process of building the first circuits. I am now only at the third one is, which uses a motor and a transistor. I successfully uploaded this example sketch and it worked.

So I wanted to make some changes, but I couldn't upload my changes, because somehow the /dev/ttyACM0 is no longer listed under Tools >Serial Port
there's only one entry: /dev/ttySO

I'm not sure why it disappeared, I don't think I installed anything on my system while trying out the uno.

I have installed the IDE on a system running Ubuntu 9.10
that's a bit dated, but shouldn't be an issue I think.
The IDE is version 0022, which, I believe, is the latest version. It lists my uno (and until yesterday, everything worked fine).

When I run dmesg I see the repeated message:
[ 6948.356061] usb 2-3: new full speed USB device using ohci_hcd and address 11
[ 6948.572215] usb 2-3: configuration #1 chosen from 1 choice
[ 6948.575705] cdc_acm 2-3:1.0: no more free acm devices
[ 7004.866986] hub 2-0:1.0: port 3 disabled by hub (EMI?), re-enabling...
[ 7004.867001] usb 2-3: USB disconnect, address 11
[ 7005.168055] usb 2-3: new full speed USB device using ohci_hcd and address 12
[ 7005.384179] usb 2-3: configuration #1 chosen from 1 choice
[ 7005.387636] cdc_acm 2-3:1.0: no more free acm devices
[ 7057.105080] hub 2-0:1.0: port 3 disabled by hub (EMI?), re-enabling...
[ 7057.105094] usb 2-3: USB disconnect, address 12
[ 7057.408290] usb 2-3: new full speed USB device using ohci_hcd and address 13
[ 7057.624241] usb 2-3: configuration #1 chosen from 1 choice
[ 7057.627760] cdc_acm 2-3:1.0: no more free acm devices
[ 7074.529459] hub 2-0:1.0: port 3 disabled by hub (EMI?), re-enabling...
[ 7074.529473] usb 2-3: USB disconnect, address 13
[ 7074.832030] usb 2-3: new full speed USB device using ohci_hcd and address 14
[ 7075.047608] usb 2-3: configuration #1 chosen from 1 choice
[ 7075.051108] cdc_acm 2-3:1.0: no more free acm devices
[ 7201.100134] usb 2-3: USB disconnect, address 14

it seems like this might be related…

If anyone has any ideas, I would be very grateful. I have seen threads that looked a bit similar, but nothing that really helped me.

2

Try to create a link:
sudo ln -sf /dev/ttyACM0 /dev/ttyS0

I'm running 11.04, if I start arduino IDE as regular user, can't get serial.
Only under root privileges.

3

Thanks, I don't really understand why I could access my uno for a couple of days and then all of a sudden I need root privileges, but anyway, I gave it a try. It doesn't work, I still only see/dev/ttySO and I get the error messages (in the IDE):
avrdude: stk500_recv (): programmer is not responding
avrdude: stk500_recv (): programmer is not responding

Though I was already getting those messages. I should have mentioned them before.

PS I will go to bed soon, but will eventually read any replies of course

4

Is the arduino plugged directly into the PC ?, if it isn't its the first thing I'd try.

5

yes, I cannot see /dev/ttyACM0 regardless of whether the board is connected or not. I have also tried different orders such as first plug in the board and then start up the IDE or the other way around. it is good advice though, because I had already noticed that the port was only available in the IDE when it was actually connected (when it still worked). I agree it is the first thing to check, but unfortunately it is not my problem.

6

Something is wrong. Have you rebooted recently, or do you just suspend/sleep a lot?

no more free acm devices

How many other ttyACM* do you have?

ls -al /dev/ttyACM*

Have you tried removing cdc_acm and usbserial modules and re inserting them?

sudo rmmod cdc_acm
sudo rmmod usbserial
sudo modprobe usbserial
sudo modprobe cdc_acm

7

I see this problem once in a while, too. So far, unplugging the USB cable, waiting a couple of seconds, and then plugging it back in has allowed Ubuntu to find the ACM port again.

Jim

8

I tried unplugging (many times) and rebooting (once or twice) when this occured. It didn't help then. Also I power down completely each day.

Today everything is back to normal it seems. The port is available from the IDE again and

ls -al /dev/ttyACM*

only returns one result:

crw-rw---- 1 root dialout 166, 0 2011-06-09 00:18 /dev/ttyACM0

Uploading a sketch went fine... I'd like to know what happened, but I'm happy it was only temporary... wel let's hope so!

Thanks for replying everyone!