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C55x Connected Audio Framework: USB IN Channel Count

Andrew Foster
Intellectual 450 points
Other Parts Discussed in Thread: TMS320C5535

Hello,

We are looking for a replacement to the TUSB3200CPAH and are investigating the suggested TMS320C5535.  Our existing design has the TUSB3200CPAH configured as a single 7.1 interface.  We are flexible on this so long that we keep the same number of channels.  I've been digging through the Connected Audio Framework documentation and have not found anything indicating the configuration options of USB Audio Class. 

Does anyone know first hand if the TMS3200C5535 along with the USB Audio Class Framework can support 8 channels USB in to 4 I2S Out?  The processor comparison page:

http://processors.wiki.ti.com/index.php/TUSB3200A_vs_TMS320C5533_Comparison#TMS320C5533_USB_Source_Code

Shows under USB Features -

TUSB3200A

Control Endpoint + 7 IN endpoints and 7 OUT endpoints

TNS320C5533

Control Endpoint + 4 IN endpoints and 4 OUT endpoints. 

But I'm not sure how to interpret this.  

What does 4 IN endpoints actually mean?

4 USB streams, or 4 channels in?

Our design needs to be able to receive a total of 8 channels over USB and output 8 digital channels (I2S).  The hardware looks like it supports this but I want to be sure there isn't anything in the framework that would preclude me from doing that?


Thanks,


Andrew

  • 0
    TI__Mastermind 30120 points

    Hi Andrew,

    "Control Endpoint + 4 IN endpoints and 4 OUT endpoints" is referring to USB endpoints and not audio channels. A single USB endpoint is used for multiple audio channels.

    What sampling frequency and bit depth do you require? 8 playback audio channels only? No record audio channels?

    The C55x USB Audio Class Framework currently operates in USB Full speed, which likely does not have the bandwidth to support 8 audio channels (maybe at a low bit depth and sampling rate).

    However, the C5535 USB peripheral supports USB2.0 High Speed, which allows scalability to 8 audio channels.

    The USB Audio Class 2.0 Framework supports 8 audio channels but is under development. You can contact your local TI representative for early releases.

    Regards,
    Mark

  • 0 in reply to Mark M
    Intellectual 450 points

    Hi Mark,

    Thanks for your reply. We currently use the TUSB3200CPAH which is a USB Audio 1.0 device (48KHz/16-Bit).  We do not need any record capabilities.  The current TUSB firmware presents itself as a single end-point supporting 8 channels.  We believe the issues we are having currently with the TUSB3200CPAH are actually architecture issues with Windows 7 and the changes that have been made to USB and USB Audio Devices.  We've tuned the operating system and bios to no avail.   It sounds like we may be better off waiting for the Audio Class 2.0 framework or looking for a different solution.

    Thanks again for your support,

    Andrew