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USB Device Requests (specifically Vendor for the RequestType)

Timothy Eastham
Intellectual 360 points

Other Parts Discussed in Thread: AM1808

I am looking for some StarterWare examples for doing USB vendor specific device requests on endpoint 0. (USB 2.0 specification section 9.3).  I need to communicate with the AM1808 from the host with vendor commands.  Preferably, commands device-to-host and host-to-device with and without a data stage would be nice...

Thanks,

Tim

  • 0
    TI__Prodigy 515 points

    Hi Timothy,

    I am sorry to inform you that StarterWare donot have  examples for vendor specific device requests.

    Vendor-ID is available in the device descriptor details. As part of the enumeration process, device descriptor would be acquired on endpoint 0 for request type 'GET_DESCRIPTOR'.

    You can try customizing the exiting examples to suit your requirement.

    Regards

    Sirish

  • 0 in reply to Naga Sirish Kumar Sannala
    Intellectual 360 points

    Vendor-ID is different than vendor requests.  Vendor requests are control transfers on endpoint 0.  Since posting I have found a mention of control transfers in general in the usbdenum.c file.  The array of importance is g_psUSBDStdRequests[].  This array is a jump table to call functions for getting the status and getting descriptors on Endpoint 0.  Would I be ok to edit this array to add the vendor type to the bmRequestType and create my own function to process vendor control transfers?

  • 0 in reply to Timothy Eastham
    TI__Prodigy 515 points

    Hi Timothy,

    "g_psUSBDStdRequests" is used for standard requests. I would suggest not to edit this array.

    You may define custom handlers and link them using the "tCustomHandlers" field of "tDeviceInfo" structure. Additionally, you will have to update "usbdenum.c: USBDReadAndDispatchRequest" to check for request type and call your vendor request handler.

    Alternatively, you may update the existing implementation, having all the non standard requests handled using "HandleRequests" function of corresponding class implementation.
    Example: MSC class
    In the definition of "usbdmsc.c: g_sMSCDeviceInfo.sCallbacks", "pfnRequestHandler" field is initialized with "HandleRequests". So, any non standard requests coming to "usbdenum.c: USBDReadAndDispatchRequest" will be handled using "usbdmsc.c: HandleRequests".
     
    Regard
    Sirish