DM368 USB connection to a device

Michele Mondini

Dear all,

I have a 4k camera that uses a DM368 processor to acquire and encode an h.264 video stream. I haven't full access to the processor but after various tests I'm sure that the video is transmitted only over 2 pins (USB D+ and D-).
I have built a custom USB OTG cable with this 2 pins + GND to connect it to a Linux Embedded System but it seems that it cannot recognize any new device plugged in or any USB-related event (check it with dmesg).

Do I need to set up a proper gadget on my Linux Embedded System before connecting the cable or the problem is related only to the wiring?

Thanks in advance.

over 8 years ago

0 Dwarakesh Radhakrishnan over 8 years ago

Guru 13660 points

Hi,

Have you made sure VBus is coming out of the DM368 ?

Yes, you need to configure a gadget device for the device to get enumerated and show something in dmesg

0 Michele Mondini over 8 years ago in reply to Dwarakesh Radhakrishnan

Prodigy 20 points

Thank you very much for the hint.

No, is it necessary for a correct video stream transmission over USB?
I thought that GND D- D+ were the only pins responsible of the data transmission as it happens in unpowered devices.

Regards

MM

0 Dwarakesh Radhakrishnan over 8 years ago in reply to Michele Mondini

Guru 13660 points

Hi,

Correct video stream is not required for detection. But atleast UVC gadget should be enabled. If it is having some issue, check the dmesg of DM36x for failuer log.

DM36x when configured as device expects voltage in VBUS. If it is given internally, then no need for external VBUS coming from the other board.

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DM368 USB connection to a device