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USB-MODEVM protocol

Garry Allen
Prodigy 20 points
Other Parts Discussed in Thread: TLV320AIC3254

I have a query about the USB-MODEVM protocol. We are looking at developing an application around the TLV320AIC3254 as a USB audio device. We have some TLV320AIC3254EVM-Ks. Looking at the user manual for these boards, Appendix G appears to define the USB-MODEVM protoocol. Table G.1 and G.2 in slau264.pdf describes the USB-MODEVM protocol. It appears to expect a 64 byte data packet where the first byte defines the interface, the second defines the address of the device, the 3rd the length of data to read or write, the 4th the register address and the remainder the data to be written.

However, when we look at the actual contents of the packets, they appear to be different.Looking at the packets in usbtrace, there actually appear to be 2 packets sent, the first containing the device address and the second containing the register address and the data to be written.

1. Is the description in rev G of slau264.pdf correct?

2.  If not, is there a document where this protocol is defined?

3. Or should we use the source posted in the forum earlier this year

thanks

Garry

  • 0
    TI__Mastermind 46195 points

    Hello Garry,

    When the AIC3254EVM-Ks were first manufactured, the firmware image loaded into the daughtercard EEPROM used the protocol mentioned in Appendix G. This protocol was used along with LabView's NI-VISA driver to communicate with the host PC.  With the release of PurePath studio, we had to change the protocol to be compatible with a more generic type (USB HID class) so we could download code within PurePath. The newest versions of the EVM-K have this new firmware image. However, the USB-MODEVM motherboard still has this old firmware loaded in (V0105), which can be accessed by removing the EEPROM jumper in the daughtercard and setting SW2.1-3 to the left in the motherboard.

    This protocol is meant for modular use (i.e. for various devices) and not for an end-user USB Audio Device. It does not implement any volume control, sample rate, enhancement operations which are common in such environment.

    If using the TAS1020B USB controller for the end product, my recommendation is to start with the FDK (http://focus.ti.com/docs/toolsw/folders/print/tas1020fdk.html) or contact Indesign for support or firmware design: http://www.indesign-llc.com/technical_support/index_web.asp.

    Regards,

    J-

  • 0 in reply to J-
    Prodigy 20 points

    Thanks for that J-