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Setting PCM2706 for Android audio development

gchaconr
Intellectual 645 points
Other Parts Discussed in Thread: PCM2706, EK-TM4C123GXL, PCM3060

Hi, I have designed a board using the PCM2706 based on the schematic from page 29 of the datasheet.

The idea is to be able to connect an smartphone running Android in order to charge it and at the same time to play music using an Android app that plays music through USB.

So far I a able to charge the phone (nothing too exciting), but the app doesn't recognize anything connected to the USB. 

Is PCM2706 the right device for this application? If so, what should be the right setting for: HOST, FUNC0:3, HID0:2, FSEL, TEST, DT, PSEL and DOUT? I have try a lot of settings but nothing.

Also, what should be the right voltages for Vbus and Vdd?

Thanks in advance for any help you could provide.

  • 0
    TI__Guru* 95035 points
    Hi,

    The PCM2706 is an USB DAC that is automatically recognized in systems that support the standard USB Audio Class.
    Vbus is the voltage from the USB host, so it should be 5V.
    Regarding to Vdd it's voltage is nominally 3.3V, if the device is in USB-powered mode, Vdd voltage will be internally generated, but if it is in Self-powered mode Vdd voltage should be provided externally.
    The other settings like HOST, FSEL, etc depends on your application requirements.

    Best regards,
    -Ivan Salazar
    Texas Instruments
  • 0
    Genius 4680 points

    gchaconr said:
    The idea is to be able to connect an smartphone running Android in order to charge it and at the same time to play music using an Android app that plays music through USB.

    Is PCM2706 the right device for this application?

    You are making something like an audio dock with charger for Android phone. PCM2706, which provides a USB peripheral (device), is wrong choice for your purpose. Android phone should work as a USB host to connect to PCM2706. In this configuration, the Android phone supplies power over the USB line to PCM2706. It means, you cannot charge the phone.

    To charge the phone, your "dock" should work as a USB host, which drives Android to sink audio stream (like a USB microphone). This cathegory is called as Android audio accessory.

    "Connecting audio over USB" on source.android.com
    https://source.android.com/devices/accessories/custom.html#audio-over-usb

    "Android Open Accessory (AOA)"
    https://source.android.com/devices/accessories/protocol.html

    There are a couple of dev kit from Google and MCU manufacturers,

    "Accessory Development Kit"
    http://developer.android.com/tools/adk/

    Atmel-Arduino - Arduino ADK R3
    Microchip - PIC24F Accessory Development Starter Kit for Android
    NXP-Embedded Artists - Android Open Accessory Application (AOAA) Kit

    But I don't recommend to buy such dev kits, because they are too expensive.
    You may do it with,
    - MCU with full-speed USB host and I2S (SPI) (ex. TI EK-TM4C123GXL, ST F4 discovery, etc.)
    - I2S (SPI) audio codec  (ex. PCM3060)

    Tsuneo