Connecting USB serial device


#1

Hello,
I’m trying to connect some USB device.
The device is detected on my Ubuntu desktop as ttyACM0 - generic serial device, and then i’m able to open communication with is by means of screen command.
On my 820c board i do not see any new tty device when it’s connected.
The Linux version is out-of-the-box 4.11.0.
lsusb detects the device ID.
dmesg : usb 1-1.1: new full-speed USB device number 16 using xhci-hcd

How can i communicate with the device ?
Does the kernel is missing some driver or configuration?

Thanks in advance.


#2

How can i communicate with the device ?
Does the kernel is missing some driver or configuration?

This works find for me on the latest snapshots (v4.14 kernel).

It is possible that the cdc_acm driver was not enabled in the
(now obsolete) v4.11 images but I think it is more likely that
you have done an apt upgrade and triggered a bug in the way
kernel updates are delivered (which cuts you off from all kernel
modules).

It’s easy to tell if you suffer from this problem because
/proc/modules will be empty! If you are suffering from this then
the problem and various workarounds are discussed here:

If that’s not the cause, then upgrading to the latest snapshot
will probably resolve the problem.


#3

Danielt,
I still didn’t connected the board to the internet, and the /proc/modules is not empty.
So i’m going to update the system.
Can you please point me to the recommended version ?

Thank you.


#4

I still didn’t connected the board to the internet, and the /proc/modules is not empty.
So i’m going to update the system.
Can you please point me to the recommended version ?

See:

The “SD image” is for bootloaders only (and this probably doesn’t need
updating unless you have a pre-production board), the files for the
fastboot method of install are what you need to update the OS on the
board.


#5

I successfully entered into the fastboot mode.
Then i burned the boot image and the rootfs image of 217 (latest) version.
Both are finished successfully.
Now the Linux doesn’t come up. The display stays blank from the power up.
What i did wrong ?
Do i have to burn some more image ?
The BT LED is On, and the user LED 0 is blinking.
Update:
I think the system is running, the problem is with display connectivity.
I tried to burn another version, the display is still blank, but sometimes with lines.


#6

Can you get in via ethernet? I think if you boot the board it will join the network automatically and be running an SSH server (default username and password are “linaro”; naturally the password should be changed ASAP).

If you are lucky you can access the board by name “linaro-alip” but if your router don’t support local lookups via DNS then you might have to use nmap or the router UI to figure out the IP address.