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The USB device mode right definition

Radosvet B.
Intellectual 490 points
Other Parts Discussed in Thread: TUSB2036

Hello!

 

 

Please see the small self-powered multimedia system application schematic attached.

 

 

The iDevice (iPhone, iPod) audiodata source sends the audiodata by the USB-interface to the AudioDAC (or to other multimedia processing device) thru the hub IC.

 

The Microcontroller (MCU) with the Control Panel is intended to control the iDevice thru USB interface too.

 

The MCU can send control commands (as the standard USB HID codes) to the iDevice.

 

The MCU, hub IC and the multimedia processing device are connected between each other permanently.

 

The iDevice is connected to the upstream port of the TUSB2036 hub IC thru the Apple Lightning to USB Camera Adapter Cable:

http://www.apple.com/shop/product/MD821AM/A/lightning-to-usb-camera-adapter

 

This multimedia system is not supplying power to the hub upstream port and to the iDevice.

 

 

The questions:

 

1.   What type of the MCU USB-class device should be (USB-Host, USB-Device, USB-OTG)?

 

2.   What the TI MCU type can you recommend for this application?

 

 

Regards,

R. B.

  • 0
    TI__Guru* 76130 points
    Hello,
    The USB interface is a Host driven interface, it is not possible that the MCU and the iDevice control each other through a USB hub, one of them must be always the Host and the other one the Device.
    It is possible for USB-OTG devices to act as a host or as a device but the USB Hubs does not support OTG, this is inherent to the USB Specification.

    The TUSB2036 will work with any USB compliant Host no matter what operating system it is in.
    Regards
  • 0 in reply to Elias Villegas M.
    Intellectual 490 points

    Thank you Elias,

     

    I understand the situation with OTG + the hub.

     

    But it is still not clear, what USB class should have the MCU in this application.

     

    Host or Device?

     

    The MCU should send (to the iDevice) the USB-HID code commands like similar PC keyboard.

     

    The iDevice receive commands and sends USB audiodata stream to the DAC.

     

    The iDevice use conventional software player programs.

     

     

    Can you clarify it?

     

     

    Regards,

    R. B.

  • 0 in reply to Radosvet B.
    TI__Guru* 76130 points
    Hello,
    In your block diagram, the iDevice should be the USB Host, the MCU should be able to enumerate as a USB Audio Device so you will need the Audio class on the MCU.
    I am not familiar with the MCUs but you can post a question at the link below.
    Regards

    e2e.ti.com/.../
  • 0 in reply to Elias Villegas M.
    Intellectual 490 points

    OK.

    It is possible for the USB HID device to send its interrupt requests to the USB-Host (and thru the Hub too)?

    Regards,

    R. B.