There are plenty of ICs that implement USB audio devices, TI PCM2902 (already used this and works fine ), Cmedia CM-108, etc. It's my understanding that usb audio devices need to implement isochronous transfers and it will not work over a bulk transfer without some major driver rewriting. Bulk transfers use unallocated bandwidth and you cannot assure timely delivery of the audio packets. I don't think its worth the trouble. There are USB controllers that implement isochronous transfers or you could use a usb codec like the ones already mentioned. Dimitri > Why don't you try UAC3554B from Micronas. It is a complete USB > headset, with ADC and DAC and the USB controller, that acts like a > standard USB Audio device. I use the codec configuration (UAC3556B), > and it works really fine! > > Bests > Tom > > Aaron Phoenix <aaronphenix@xxxxxxxxx> írta: > > > Hi all, > > > > We are going to build a USB microphone device with a > > USB device controller, which has four endpoints: > > ------- > > Endpoint 0: 8-byte FIFO support for Control transfer; > > Endpoint 1: 64-byte FIFO support for Bulk-In/Bulk-Out > > transfer; > > Endpoint 2: 8-byte FIFO support for > > Bulk-Out/Interrupt-Out transfer; > > Endpoint 3: 64-byte FIFO support for > > Interrupt-In/Bulk-In Transfer. > > ------- > > > > Now there is a USBD_STATUS_STALL_PID error when the > > call URB_FUNCTION_SELECT_CONFIGURATION returns. Here > > are the debug messages from firmware: > > ------- > > reset > > reset > > [80 06 00 01 00 00 40 00] USB_DT_DEVICE, ok > > reset > > [80 06 00 01 00 00 12 00] USB_DT_DEVICE, ok > > [80 06 00 02 00 00 09 00] USB_DT_CONFIG, ok > > [80 06 00 02 00 00 FF 00] USB_DT_CONFIG, ok > > [80 06 00 03 00 00 FF 00] USB_DT_STRING, ok > > [80 06 02 03 09 04 FF 00] USB_DT_STRING, ok > > [80 06 00 03 00 00 FF 00] USB_DT_STRING, ok > > [80 06 02 03 09 04 FF 00] USB_DT_STRING, ok > > [80 06 00 01 00 00 12 00] USB_DT_DEVICE, ok > > [80 06 00 02 00 00 09 00] USB_DT_CONFIG, ok > > [80 06 00 02 00 00 64 00] USB_DT_CONFIG, ok > > -->error, firmware dectects the STALL status. > > ------- > > > > This USB device controller automatically responds to > > > SET_CONFIGURATION/GET_CONFIGURATION/SET_FEATURE/CLEAR_FEAT > URE/SET_INTERFACE/GET_INTERFACE/SET_ADDRESS/GET_STATUS. > > And we have made USB Mass Storage and USB HID > > mouse&keyboard devices with this chip, all they work > > well. > > > > Is it possible to build a USB audio device needs > > Isochronous pipes with a Bulk-only USB device > > controller? How do the values of bmAttributes field of > > Endpoint Descriptor affect the host&device > > controllers? We need the expert opinions to decide to > > give up or go on with the project. Thank you! > > > > Regards, > > Aaron M. Phoenix > > > > > > > > > > __________________________________ > > Do you Yahoo!? > > Meet the all-new My Yahoo! - Try it today! > > http://my.yahoo.com > > > > > > ****************** > > > > WDMAUDIODEV addresses: > > Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx > > Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx? > subject=subscribe > > Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx? > subject=unsubscribe > > Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx > > > > URL to WDMAUDIODEV page: > > http://www.wdmaudiodev.de/ > > > > > > > ****************** > > WDMAUDIODEV addresses: > Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx > Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe > Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe > Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx > > URL to WDMAUDIODEV page: > http://www.wdmaudiodev.de/ > > > ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.de/