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  • Case ID: 303586
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I2S LRCK FREQ

Shariff

Hi, 

I am trying to develop an MP3 player I want to configure LRCK to 44100 but I only able to configure it to 43530 with configuration available in document as CONFIG.RATIO = 32X and CONFIG.MCKFREQ = 32MDIV23.

The exact configuration that I want is CONFIG.RATIO = 256X and CONFIG.MCKFREQ = 32MDIV3. Is there any formula to configure these frequencies since it is not defined in the SDK17.1.0

Thanks and regards.

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    Which codec do you use? Its sometimes simpler to make the codec chip the I²S master, especially if it has a PLL.

    The electrical spec in PS limits MCK to 4 MHz maximum, that is why you cannot have a divider smaller than 8 agains the 32 MHz clock source.

    Note that I don't think that the NRF52840 will be fast enough for real time MP3 decoding, even the NRF5340 will be at the limit.

    I've used minimp3 on a 600 MHz Teensy 4.1, it runs at roughly 50% CPU usage with a high quality MP3 file.

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  • 0

    Which codec do you use? Its sometimes simpler to make the codec chip the I²S master, especially if it has a PLL.

    The electrical spec in PS limits MCK to 4 MHz maximum, that is why you cannot have a divider smaller than 8 agains the 32 MHz clock source.

    Note that I don't think that the NRF52840 will be fast enough for real time MP3 decoding, even the NRF5340 will be at the limit.

    I've used minimp3 on a 600 MHz Teensy 4.1, it runs at roughly 50% CPU usage with a high quality MP3 file.

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