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SRC4392 Output rate and DIT status bits problem.

Edward Insam
Prodigy 20 points
Other Parts Discussed in Thread: SRC4392

I have a standard SRC4392 setup using a 12.288Mhz external oscillator. I can write to the DIT page 2 registers OK, and when operated at 96K frame rate, all signals, sound, and channel status bits are reported OK on my dScope II AES audio analyser. I am also using port A and B for input etc, but all that is OK.

Problems arise when I try to run at 48K (by changing TXDIV[1:0] in register 7 from 00 to 01) The audio and frames look OK on the dScope, but the DIT status bit display show all zeros, with the dScope reporting "Block Length Error" Which is defined as "distance between Z frames not 192 bits"  

What am I doing wrong? I only need to operate at 96k and 48k, but I cannot change the 12.288 external source.

Here are my Page 0 register settings:

Register 07: 0x1C for 96k, 0x3C for 48k
Register 08: 0x00 or 0x08 depending on page 2 writes
Register 09: 0x01
Register 2E: 0x00
Register 2F: 0x00
Register 2D: 0x00

Anything I may have missed? Thanks

  • 0
    TI__Guru**** 189399 points

    Hi, Edward,

    Welcome to e2e, and thanks for your interest in our products!

    Do you mind if I ask you how you found e2e?

    As for your question on the SRC4392, I have asked my colleague to look at that for you early this week.

    -d2

  • 0 in reply to Don Dapkus
    TI__Genius 16270 points

    Edward,

    It seems based on the script that the SRC is the input source for the DIT, but Port A is the source for the SRC.  When adjusting sampling rate dividers for the DIT, what changes are being made to the Port A registers 03/04?

  • 0 in reply to Patrick Galvin
    Prodigy 20 points

    Yes the SRC is the source to the DIT, and PortA the source for the SRC.

    PortA works in master mode, with frame clocks and data supplied by an external A/D converter (running at 48Kbs). MCLK is a master 12.88MHz oscillator, common to all devices on the board.

    PortA is initialised as follows

    Register 03 = 0x41 = I2S,24b, Master

    Register 04 = 0x00 or 0x01 Divide by 128 or 256. I have actually tried both combinations at either speed with similar results.i.e. the block framing error is still there.

    Any other tests I can perform?

    Regards