JeNeVoisPas, no image from the camera

Question

Hi,

Try as I might, I cannot get an image from JeVois. I have used guvcview, vlc and ffplay on Kubuntu 16.10 and 17.04.

I know the software is running because I can connect to the serial console and type commands like "info","help" and get an answer.

JeVois is connected to a USB 3.0 port and all the LED look OK.

When using  guvcview, I get a message tto the effect that it can not set 30 fps, followed by lots of

    V4L2_CORE: (get_v4l2_frame) video stream must be started first

After quitting the software, the device (both video1 and ttyACM0) dissapear.

I use the command

    guvcview -ao none -f YUYV -x 640x360 -d /dev/video1

When using the other USB camera connected to my computer (video0) I have no problem at all.

I have 2 JeVois camera and this problems happens with both. I used both the old and the new MicroSD images.

What am I doing wrong?

Answer 1

Try using a USB 2.0 port on your computer if there.  Many times this is a dedicated keyboard & mouse port.  If you do not have a USB 2.0 Port, try using a USB 2.0 Hub.  There are problems with inexpensive USB 2.0 chips from china that cause timing and other problems with USB 3.0.

I had this problem on my computer and solved it by switching ports.

Comments

Thanks for answering... tried different ports, different computer (Dell laptop) same problem. I will try with a RPi3 when I get the time.

Answer 2

Althouvgh highly unlikely, you might have received two of the few bad units that have slipped through the quality control before we started doing double burn-testing on all units.

Are you using the USB cables provided by JeVois? If not, maybe try to use some USB cables rated for charging and/or mentioning 24AWG wire size (this means the cable can carry enough power needed by JeVois).

If you see JeVois being detected when you type dmesg but guvcview fails, then it could indeed be a bad cable (rated for data sync only). We have been able to reproduce this behavior with data-sync-only USB cables. The fact that you can type info, help, etc also points towards a weak USB cable. Do you lose the serial console after you start guvcview and it cannot grab (i.e., is JeVois crashing)?

With a RPI3 make sure you use a Y-type cable and connect the short end (power only) to an external source (e.g., USB charger).

Please contact us through Kickstarter (send message to creator) and maybe we just send you new units and cables to test.