USB hotplug

Hi All!

I have EBVBeagle C2 and use Koen’s demo images from http://www.angstrom-distribution.org/demo/beagleboard/ (kernel 2.6.29). USB mouse works perfect only when I connect it before the board powerup. If I intentionally disconnect it and then connect it again - the mouse will never work again.

Yes, I’ve read about this issue and the problem is suggested to be fixed by more stable power rail. I’ve looked into SMSC reference design for the USB transceiver and didn’t find there any huge capacitors or ferrite filters. Only 0.1u ceramics as usual.
Here is what is written in the usb3322 product brief:

Ability to tolerate “noisy” clocks and power supplies | Does not require costly filtering or clock generator circuits to preserve Hi-Speed eye diagram integrity.
<<
Please correct me if I’m wrong

Can it be a software issue? May be it is fixed in more recent kernels?
Please clarify.

regards,
Max

It could also be poorly designed pcb.

Ionut Cotoi
Senior Software Developer
Tel: 0721262666
http://icotoi.ro

The Rev C2 design has a noise issue on the USB host port. I think everyone should already know this by now. But, I don’t know of any relationship to unplugging and pluggging back in a USB cable related to this issue. Rev C4 is the board that has solved the noise issue. Expect to have Host issues on the Rev C2 design.

Gerald

Gerald,

Of course I know about the noise issue and I stated this in the first message. SMSC say that only 2.2uF is required for usb3322. Why was it necessary to use filter and huge ceramic capacitor? Can it be the poorly designed PCB?

Frankly speaking at my SODIMM module I used usb3320 without any complex filtering and the USB works exactly as at C2. I am pretty sure that two men can’t make the same mistake in trace routing of the PCB. How did you find the noise issue?

Max

2010/3/2 Gerald Coley <gerald@beagleboard.org>

It is not a poorly designed PCB. Othewise you would see the issue on the C$. It is the same base design as the Rev C4. The EBV C2 is the same as the Rev C2 Beagle. They tok the open source stuff, changed the color, and added the EBV name.

Gerald

Why USB devices can’t be changed during work without a lost of the functionality? My ancient system with sam9263 accept hot changes of any USB devices and everything works just perfect in the Buildroot or Angstrom environment…

regards,
Max

2010/3/2 Gerald Coley <gerald@beagleboard.org>

It works fine on my Rev C3 and Rev C4 Beagleboards. This is actually part of the test we do before the boards ship.

Gerald

What we use can be found here:

http://code.google.com/p/beagleboard/wiki/BeagleboardRevCValidation

Gerald

I’ve checked again the hotplug feature and found that dynamic change of USB devices is allowed at least for USB flash drives. You can’t remove and insert back the USB mouse, it simply stops to work. But USB flash can be removed and inserted back a few times with no loss of functionality.

Well I’m glad I could find that flash drives are hotplug capable. Mouse change can be a restriction :). But as I’ve written in the previous mail - USB mouses, keyboards or anything else can be changed any time at sam9263 system which is a great advance.

regards,
Max

2010/3/2 Gerald Coley <gerald@beagleboard.org>