usb compatibility : about notebook and pc

[freeliver]

I'm design a usb device, the max current is 500mA, normal is 300mA. Now I face a proble : my device can work on pc and many notebook, but on some notebook it does't work.

What's special on notebook's USB port ? I see the configration of notebook that the port is 500mA.

 

[ASIC]

The 500 mA is shared between the devices. Does the notebook have any internal devices that are USB? Do you report a 500 mA device in your descriptor? Try to report 100 mA to verify this is the problem


ASIC

 

[freeliver]

no other device. The notebook which I tried is IBM's. It has a DVD which is plug-in device, but it's not a USB device. I tried the 100mA , my usb device doesn't work. But it can work on the hub which connect to this notebook USB port.

 

[freeliver]

I tried again.Now, my device can work on the hub even which is bus-powed hub and conneted to the notebook USB port!

So I think it's not the power problem.

 

[ASIC]

Does it go wrong during enumeration?

Does your device pass enumeration on both the notebook, external hub and other PCs?

Maybe your device is not compliant. There is some slight difference between UHCI and OHCI hubs that you must work around in your device firmware

I suspect your notebook is OHCI and the rest is UHCI.

Let me know if that made sense?

ASIC

 

[freeliver]

Those PCs' usb host which I tried are two kinds:
1 pci to usb open host controller
2 usb universal host contrller

the notebook's USB host is pci to usb universal host cntroller.

 

[freeliver]

I think my device pass enumeration on both the notebook, external hub and other PCs ,because it's been seen the current of the device is 500mA,which is the device configed.

 

[ASIC]

Ummmm.... Sounds like a chipset/driver problem with your notebook. Any support info on IBM's web-site?

OR, could it be a power management problem?


ASIC

 

[freeliver]

I tried another notebook now : NEC notebook.Its host controller is Intel 82440MX USB Universal host controller. My device work OK!

 

[freeliver]

who used mic2550/2550a ?

Now I think it's proble of mic2550/mic2550a which I used .

Who once used it?