screen /dev/ttyUSB0 115200 fails with [screen is terminating]

[brianthelion]

• Doc you were trying to follow: https://coral.withgoogle.com/tutorials/devboard/
• Your host OS: Ubuntu 18.04
• Your Python3 version: 3.6.7

What I ran

When running the Getting Started tutorial, I everything went smoothly up to:

$ dmesg | grep ttyUSB
[11567.500409] usb 1-2: cp210x converter now attached to ttyUSB0
[11567.503236] usb 1-2: cp210x converter now attached to ttyUSB1
[11569.062428] cp210x ttyUSB1: failed set req 0x1e size 4 status: -32
[11569.062443] cp210x ttyUSB1: failed to set baud rate to 300

and then

$ screen /dev/ttyUSB0 115200

What the docs said should happen

"Terminal should go blank."

What actually happened

$ screen /dev/ttyUSB0 115200
[screen is terminating]

[brianthelion]

Not sure what's up with the dmesg output but I think it's orthogonal to the screen issue. The screen issue I believe is due to udev permissions. It's quickly solved with:

$ sudo screen /dev/ttyUSB0 115200

[hughpyle]

Alternatively: the /dev/ttyUSB0 should be group-writeable by 'dialout', so add your user to the 'dialout' group:

sudo usermod -a -G dialout $USER

then you'll be able to run screen without sudo.

[taunusflieger]

Are you trying to connect from within a VM? Got the same when using a Parallel VM. I ended up using a Raspberry PI as the Linux box for installation

[brianthelion]

No, I was connecting from a Thinkpad running Ubuntu.

[asnare]

When getting started there are two USB devices that are used:

• The first is a UART bridge that you use get the serial console. This is normally /dev/ttyUSB0 after you plug it in.
• The second is the OTG/data port where the firmware gets uploaded. The udev rule in the documentation (covering device with vendor id 0525) ensures this gets the right permissions for fastboot to do its thing.

Unfortunately there's no udev rule for the first (terminal) device (vendor id 10c4) which means that screen probably can't open it.

I fixed this by adding an additional rule to cover the first device, after which my /etc/udev/65-edgetpu-board.rules file looked like this:

SUBSYSTEMS=="usb",ATTRS{idVendor}=="10c4",MODE="0664",GROUP="plugdev",TAG+="uaccess"
SUBSYSTEMS=="usb",ATTRS{idVendor}=="0525",MODE="0664",GROUP="plugdev",TAG+="uaccess"

Note that there's also a difference from the docs here in that these lines start with SUBSYSTEMS instead of SUBSYSTEM.

With this minor change the rest of the QuickStart worked for me.

Setup: Debian 9.8 (VM) on a macOS Host (Virtualised via VMWare Fusion with USB 3.0 passthrough)

[racky1]

So I had this problem when using an Ubuntu box so I used a Raspberry Pi 3 and was able to flash the unit with the instructions.

[BarryLYH]

Alternatively: the /dev/ttyUSB0 should be group-writeable by 'dialout', so add your user to the 'dialout' group:

sudo usermod -a -G dialout $USER

then you'll be able to run screen without sudo.

I tried it and now I can connect to ttyUSB0. However, when I went to step "fastboot devices", I cannot find the ttyUSB1. Do you have any idea of that?

[Namburger]

@BarryLYH you shouldn't need both /dev/ttyUSB0 and /dev/ttyUSB1, could you clarify?

[TruckDynasty]

For anyone winding up here from a search engine: you generally need to add your user to both 'dialout' and 'tty'

[phnjau]

My problem is that i get into the serial port and it gives me a bunch of question marks and I can't even type anything and what supposed to do is type "AT".Do you think any of you guys can give me some tips?

Thanks