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pcm1753 doesn't work

Other Parts Discussed in Thread: PCM1753

Hello all!

i have some little problem with PCM1752. It doesn't work for me.

I use it with MSP430. Sample rate 16kHz, System clock 2,048 MHz, 24 bit left justified.

But on the output I see random signal with low amplitude (sm attach)

Clock for MSP430 and (thence) for DAC I get from internal 32768 Hz oscillator (after PLL).

BCK for DAC is about 740 kHz, LR ~15,4 kHz. Could there be a problem in the inaccurate frequency? Quality of output sound isn't actual.

Thanks for help!!!

  • Hi, KY,

    Do your clock conditions fall within Table 1 of the d/s on the PCM1753?

    -d2


  • Hello! Thanks for reply!

    Yes. Frequency of my clock is approximately 2,048 MHz. I say "approximately" because all clocks are derived from internal 32768 clock (from MSP430). But BCK and SCK should be synchronous because they are all derived from the same clock.

    One thing I would note: LR is switched in interrupt from timer with clock == sample rate (16kHz), therefore data transmission also starts in this interrupt. May it causes some problems in synchronization in DAC?

  • This image contains scope of LR and BACK signals.
    Sample rate = 8 kHz.
    I want note about configuration of registers.
    Neither "Mute enable" (reg 18) nor "Attenuation = 0"(reg 10, 11) don't affect on output signal, which is shown in first post. But "channel disable" works proper. What does it mean?

  • I came back to my problem. Ii is still actual :(

    Is it critical, that sample rate doesn't equal exactly to values from table? I suppose, that only relation between sample rate and SCLK should be satisfied. Correct me if I wrong.

    My sample rate is near 10kHz, hence the SCLK is near 1,920 MHz. Sample rate is derived from SCLK. I am attaching the waveform to clarify the situation.

    1. Scheme of using PCM1753

    4807.Schematic Prints.pdf

    2. Configuration of PCM1753 via SPI

    3. Data on I2S bus (second image is more detailed.

    4. Waveform from PCM1753 output.

    Frequency of output is equal to 2*F_sample_rate.

    If I set input format for PCM1753 to I2S (or any other non default), waveform on output is look like as one in my first post in this topic.

    What's wrong? What additional tests can I perform to clarify situation?

    Thanks!