Adapting hidusbfx2 sample to use isoc transfers
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From: sinosoidal on 2 Sep 2009 07:22 Hi, I'm adapting hidusbfx2 sample to use isoc transfer. To do that i'm basing myself on the usbsamp sample. While in the first, a continuous reader is being used to get the data from the device and we just need to configure the reader and start it, the second, has a lot more configuration and it prepares a scenario for handling explict IO control codes. My questions resides if the isoc transfers are always happening but the data is only transfered to the user mode on request or if, the user mode request triggers the data request from the device at that point. I wanted a similar schema in order to start the reading and have something similar like a callback on data request completion. Otherwise, the only thing that occurs to me at this point is that I'll need some kind of timer to invoke the ReadIsocPipe function from time to time. As I don't know very well the possibilities provided by the WDK I would love to hear the opinion of more experienced users and developers. With my best regards, Nuno
From: Tim Roberts on 4 Sep 2009 00:32 sinosoidal <sinosoidal(a)discussions.microsoft.com> wrote: > >I'm adapting hidusbfx2 sample to use isoc transfer. To do that i'm basing >myself on the usbsamp sample. HID devices cannot use isochronous pipes. They are required to use interrupt. That's part of the HID class spec. >My questions resides if the isoc transfers are always happening but the data >is only transfered to the user mode on request or if, the user mode request >triggers the data request from the device at that point. It depends on what you need. Both schemes are done. Sometimes, the driver creates its own set of URBs, copying into its own circular buffer, and returns data to the user mode app when needed. Sometimes, the driver waits for a request from above. >I wanted a similar schema in order to start the reading and have something >similar like a callback on data request completion. Fine. That's commonly done. >As I don't know very well the possibilities provided by the WDK I would love >to hear the opinion of more experienced users and developers. Opinion on what? -- Tim Roberts, timr(a)probo.com Providenza & Boekelheide, Inc.
From: sinosoidal on 4 Sep 2009 04:54 Hi Tim, Maybe you don't know hidusbfxz2 sample. What it does is to map a non hid device, which in this case is a usb device based on bulk transfers to a hid device, using a miniport driver. Of course I know that HID don't support iso transfer! :) As I have told you the other response you gave me is that I don't know how to prepare the invocation of isoc transfers without being based on user requests because the only reference code I have is the usbsamp for isoc transfers. If you could point me out an example in which this is done in other way or something else that helps me to understand what has to be done in order to accomplish that. I have a very reduced knowledge about WDK and its foundations because i'm only working with this for the last 2 months. With my best regards, Nuno "Tim Roberts" wrote: > sinosoidal <sinosoidal(a)discussions.microsoft.com> wrote: > > > >I'm adapting hidusbfx2 sample to use isoc transfer. To do that i'm basing > >myself on the usbsamp sample. > > HID devices cannot use isochronous pipes. They are required to use > interrupt. That's part of the HID class spec. > > >My questions resides if the isoc transfers are always happening but the data > >is only transfered to the user mode on request or if, the user mode request > >triggers the data request from the device at that point. > > It depends on what you need. Both schemes are done. Sometimes, the driver > creates its own set of URBs, copying into its own circular buffer, and > returns data to the user mode app when needed. Sometimes, the driver waits > for a request from above. > > >I wanted a similar schema in order to start the reading and have something > >similar like a callback on data request completion. > > Fine. That's commonly done. > > >As I don't know very well the possibilities provided by the WDK I would love > >to hear the opinion of more experienced users and developers. > > Opinion on what? > -- > Tim Roberts, timr(a)probo.com > Providenza & Boekelheide, Inc. >
From: Egidio [MSFT] on 4 Sep 2009 12:23 Doesn't look like there are other samples on this (do a search for 'isoc' in the sample directory). Isoc input is not very common and how it is done depends a lot on the type of technology that sits behind the USB bus: Bluetooth, audio/video, proprietary device, other. I.e., each environment has it own standards and constraints on how the isoc transfer needs to be accomplished. Like Tim suggested, one possible solutions is: (a) app sends down an irp to let the driver know when to start reading. (b) driver reads input with a isoc continuous reader, puts data in its internal buffer. (c) app sends down other irps to read this data Egi. "sinosoidal" <sinosoidal(a)discussions.microsoft.com> wrote in message news:920CB12C-8C9E-46D2-A632-FD5C39399771(a)microsoft.com... > Hi Tim, > > Maybe you don't know hidusbfxz2 sample. What it does is to map a non hid > device, which in this case is a usb device based on bulk transfers to a > hid > device, using a miniport driver. Of course I know that HID don't support > iso > transfer! :) > > As I have told you the other response you gave me is that I don't know how > to prepare the invocation of isoc transfers without being based on user > requests because the only reference code I have is the usbsamp for isoc > transfers. > > If you could point me out an example in which this is done in other way or > something else that helps me to understand what has to be done in order to > accomplish that. > > I have a very reduced knowledge about WDK and its foundations because i'm > only working with this for the last 2 months. > > With my best regards, > > Nuno > > "Tim Roberts" wrote: > >> sinosoidal <sinosoidal(a)discussions.microsoft.com> wrote: >> > >> >I'm adapting hidusbfx2 sample to use isoc transfer. To do that i'm >> >basing >> >myself on the usbsamp sample. >> >> HID devices cannot use isochronous pipes. They are required to use >> interrupt. That's part of the HID class spec. >> >> >My questions resides if the isoc transfers are always happening but the >> >data >> >is only transfered to the user mode on request or if, the user mode >> >request >> >triggers the data request from the device at that point. >> >> It depends on what you need. Both schemes are done. Sometimes, the >> driver >> creates its own set of URBs, copying into its own circular buffer, and >> returns data to the user mode app when needed. Sometimes, the driver >> waits >> for a request from above. >> >> >I wanted a similar schema in order to start the reading and have >> >something >> >similar like a callback on data request completion. >> >> Fine. That's commonly done. >> >> >As I don't know very well the possibilities provided by the WDK I would >> >love >> >to hear the opinion of more experienced users and developers. >> >> Opinion on what? >> -- >> Tim Roberts, timr(a)probo.com >> Providenza & Boekelheide, Inc. >>
From: sinosoidal on 4 Sep 2009 12:33
Hi Egidio, I would for the b option, however, as I know there is no continuous reader for isoc endpoints... right? At least, I have tried already and they don't work... am I right? That would be the most easy option. Please tell me that i'm wrong! :P Nuno "Egidio [MSFT]" wrote: > Doesn't look like there are other samples on this (do a search for 'isoc' in > the sample directory). > Isoc input is not very common and how it is done depends a lot on the type > of technology that sits behind the USB bus: Bluetooth, audio/video, > proprietary device, other. I.e., each environment has it own standards and > constraints on how the isoc transfer needs to be accomplished. > Like Tim suggested, one possible solutions is: > (a) app sends down an irp to let the driver know when to start reading. > (b) driver reads input with a isoc continuous reader, puts data in its > internal buffer. > (c) app sends down other irps to read this data > > Egi. > > > "sinosoidal" <sinosoidal(a)discussions.microsoft.com> wrote in message > news:920CB12C-8C9E-46D2-A632-FD5C39399771(a)microsoft.com... > > Hi Tim, > > > > Maybe you don't know hidusbfxz2 sample. What it does is to map a non hid > > device, which in this case is a usb device based on bulk transfers to a > > hid > > device, using a miniport driver. Of course I know that HID don't support > > iso > > transfer! :) > > > > As I have told you the other response you gave me is that I don't know how > > to prepare the invocation of isoc transfers without being based on user > > requests because the only reference code I have is the usbsamp for isoc > > transfers. > > > > If you could point me out an example in which this is done in other way or > > something else that helps me to understand what has to be done in order to > > accomplish that. > > > > I have a very reduced knowledge about WDK and its foundations because i'm > > only working with this for the last 2 months. > > > > With my best regards, > > > > Nuno > > > > "Tim Roberts" wrote: > > > >> sinosoidal <sinosoidal(a)discussions.microsoft.com> wrote: > >> > > >> >I'm adapting hidusbfx2 sample to use isoc transfer. To do that i'm > >> >basing > >> >myself on the usbsamp sample. > >> > >> HID devices cannot use isochronous pipes. They are required to use > >> interrupt. That's part of the HID class spec. > >> > >> >My questions resides if the isoc transfers are always happening but the > >> >data > >> >is only transfered to the user mode on request or if, the user mode > >> >request > >> >triggers the data request from the device at that point. > >> > >> It depends on what you need. Both schemes are done. Sometimes, the > >> driver > >> creates its own set of URBs, copying into its own circular buffer, and > >> returns data to the user mode app when needed. Sometimes, the driver > >> waits > >> for a request from above. > >> > >> >I wanted a similar schema in order to start the reading and have > >> >something > >> >similar like a callback on data request completion. > >> > >> Fine. That's commonly done. > >> > >> >As I don't know very well the possibilities provided by the WDK I would > >> >love > >> >to hear the opinion of more experienced users and developers. > >> > >> Opinion on what? > >> -- > >> Tim Roberts, timr(a)probo.com > >> Providenza & Boekelheide, Inc. > >> > |