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LM48901 eval board, GUI, and registers

Ron Sturtevant
Intellectual 290 points
Other Parts Discussed in Thread: USB2ANY

Question about the LM48901 eval board and the LM48901 registers.

I programmed the eval board using the GUI (basic stereo mode, no spatial coefficients loaded), then removed the USB2ANY connector and attached the SCL and SDA lines from my LM3S9D96 eval board to the correct connectors.  The LM48901 eval  board still played audio just fine.  I then ran an application on the Stellaris to read the LM48901 registers (0x500 to 0x507) over I2C, and even though the addressing headers looked normal on scope, all 4 bytes of all registers came back as 0xff values.  Any idea what is causing this, and how to fix it?

Or, can someone supply a mapping of the LM48901 registers look like after the initial scan has activated the chip to play audio?  I want to compare what the GUI is displaying with the actual register values.

Ron

  • 0
    TI__Expert 3840 points

    Hi Ron,

    Someone should be getting back to you shortly.

    Best Regards,

    JD

  • 0
    TI__Expert 3350 points

    Ron,

    You can use the MemReg tool in the GUI to check the contents of the LM48901 registers.  If you hit Refresh, the GUI will read back from the device.  Otherwise, you should be able to read from the device, disconnecting the USB2ANY should not affect the device. What might be happening is the GUI is changing the device address.  The GUI was designed for daisy chaining, so when the GUI detects that a device is connected, it assigns a new device address.  Check register 0x530 bits 6:0 to see what the GUI has changed the device address to.

    Regards,

    royce