-----Original Message----- From: usb-bounces@opencores.org [mailto:usb-bounces@opencores.org]On Behalf Of Lifeng Chen Sent: Thursday, February 05, 2004 7:45 PM To: Discussion list about free,open source USB IP core Subject: [usb] Help about Hi all, Can anyone help me out with these questions: 1. It's said in the USB2.0 spec section 9.6.5 (P267) that,"Interface descriptors cannot be directly accessed with a GetDescriptor() or SetDescriptor() request." So my question is: can I access them indirectly? and how? e.g. if I wanna modify an Interface descriptor, call the GetDescriptor() ? give me some details pls. 2.I'm developing an OTG device. which will interface USB bus via philips ISP1301. However I can't find the datasheet at philips website or anywhere else. Anyone has idea about the I2C transceiver interface? and send me a copy of the datasheet? many thx Joe Feb 6th. _______________________________________________ http://www.opencores.org/mailman/listinfo/usb

Interface descriptors are transferred as part of the configuration descriptor. GetDescriptor(configuration) is the way. What do you mean "modify" the interface descriptor? Set_Interface allows the host to select from alternate interfaces, if they exist, for a given configuration. It is an optional command. http://www.semiconductors.philips.com/acrobat/usermanuals/UM10028_1.pdf might help for how to connect it. Marc Reinig System Solutions Windows Driver and Embedded Product Consulting _______________________________________________ http://www.opencores.org/mailman/listinfo/usb

Hi, Marc

Thx for your kindly help :-)

My question should be : Is it possible to use SetDescriptor Request (but not GetDescriptor) to modify the Interface Descriptor. ? or is it recommended to do so ?

Here "modify" means to modify the content of an interface descriptor, e.g., bNumEndpoints field .


Another problem: According to the USB2.0 spec, only 1 device is in presence. But what's the factual situation? What's the general solution? Do we need multiple device descriptors in case of OTG development, where CBI/Bulk Only/Still Image/etc. Class are all potential devices? Alllowing the Application Software to implement multiple Device Descriptors and select an approximate one to respond to the host ? or 1 single Device Descriptor with multiple Configuration/Interface Descriptors ?

On Mon, 2004-02-09 at 15:27, Lifeng Chen wrote:


Why not ?

You can also use the vendor IO to modify your descriptors.

However I do not see WHY you would want to do that.

One device ? Hmmm, not sure what you are referring. USB bus support up to 128 devices if I remember correctly. OTG on the other hand is a pure point to point connection and supports only one device AT A TIME. There are descriptors for the entire interface and for each endpoint in every device. I don't understand what the confusion is ... OTG is only required to support specific devices. Thats more of a "deriver" issue ... Regards, rudi ======================================================== ASICS.ws ::: Solutions for your ASIC/FPGA needs ::: ..............::: FPGAs * Full Custom ICs * IP Cores ::: FREE IP Cores -> http://www.asics.ws/ http://www.opencores.org/mailman/listinfo/usb

-----Original Message----- From: usb-bounces@opencores.org [mailto:usb-bounces@opencores.org]On Behalf Of Rudolf Usselmann Sent: Monday, February 09, 2004 12:47 AM To: Discussion list about free, open source USB IP core Subject: Re: [usb] Help about On Mon, 2004-02-09 at 15:27, Lifeng Chen wrote:
Request (but not GetDescriptor) to modify the Interface
Descriptor. ? or is it recommended to do so ?

Why not ?

You can also use the vendor IO to modify your descriptors.

However I do not see WHY you would want to do that.


descriptor, e.g., bNumEndpoints field .

in presence. But what's the factual situation? What's the
general solution? Do we need multiple device descriptors in case
of OTG development, where CBI/Bulk Only/Still Image/etc. Class
are all potential devices? Alllowing the Application Software to
implement multiple Device Descriptors and select an approximate
one to respond to the host ? or 1 single Device Descriptor with
multiple Configuration/Interface Descriptors ?

One device ? Hmmm, not sure what you are referring. USB
bus support up to 128 devices if I remember correctly.
OTG on the other hand is a pure point to point connection
and supports only one device AT A TIME.

There are descriptors for the entire interface and for each endpoint in every device. I don't understand what the confusion is ... OTG is only required to support specific devices. Thats more of a "deriver" issue ... Regards, rudi ======================================================== ASICS.ws ::: Solutions for your ASIC/FPGA needs ::: ..............::: FPGAs * Full Custom ICs * IP Cores ::: FREE IP Cores -> http://www.asics.ws/ _______________________________________________ http://www.opencores.org/mailman/listinfo/usb

-----Original Message----- From: usb-bounces@opencores.org [mailto:usb-bounces@opencores.org]On Behalf Of Lifeng Chen Sent: Monday, February 09, 2004 1:06 AM To: rudi@asics.ws; Discussion list about free,open source USB IP core Subject: Re: [usb] Help about Dear Rudi, Excuse me for my carelessness. //blush. What I meant should be a single "device descriptor" rather than "device" for my OTG controller. Now I'd like to repeat my question here: According to the USB2.0 spec, only 1 device DESCRIPTOR is in presence. But what's the factual situation? What's the general solution? Do we need multiple device descriptors in case of OTG DEVICE development, where CBI/Bulk Only/Still Image/etc. Class are all potential devices? Alllowing the Application Software to implement multiple Device Descriptors and select an approximate one to respond to the host ? or 1 single Device Descriptor with multiple Configuration/Interface Descriptors ? Best Rgds, ------------------------------- Joe ----- Original Message ----- From: "Rudolf Usselmann" To: "Discussion list about free, open source USB IP core" Sent: Monday, February 09, 2004 4:47 PM Subject: Re: [usb] Help about