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Original question:

PCM1681: Connection between PCM1681 and PLL170X

PCM1681: Connection between PCM1681 and CC2640R2F

Mariano
Intellectual 285 points
Part Number: PCM1681
Other Parts Discussed in Thread: CC2640R2F, CC3200AUDBOOST

Hello team,

I am working in a project which it is necessary to use the CC2640R2F I2S peripheral to transmit audio to PCM1681 (or similar) with frequency sample of 48KHz.

The BCK is 2.304MHz once the audio has 24 bits with 2 channels. Is it possible the microcontroller CC2640R2F provide BCK of 2.304 and SCK of 12.288MHz???

Thanks in advanced.

  • 0
    TI__Guru* 99560 points

    Hi,

    Your requirements won't allow you to use the CC2640R2F as "I2S master". The CC2640R2F does not have a PLL, so the 48MHz clock has to be divided an integer number of time to produce the SCK clock. On the top of that, SCK clock frequency should be between 47 kHz and 4 MHz.

    You may want to try to use the CC2640R2F as a "I2S slave", however, this configuration has not been tested for SCK clock frequency higher than 4MHz.

    I hope this will help,

    Best regards,

  • 0
    TI__Guru**** 208417 points

    Hello Mariano,

    The maximum sampling rate for the SimpleLink I2S Driver is 44.1 kHz.  This is definitely possible with 16 bits at 44.1 kHz after audio compression, however 24 bits could surpass feasibility.  https://e2e.ti.com/f/1/t/833683 

    Regards,
    Ryan

  • 0 in reply to Clément
    Intellectual 285 points

    Hi,

    So I could use a PLL1700 as master to generate the clock for CC2640R2F and PCM1681? Something like this:

    - What do happen if I use a SCK higher than 4MHz?

    - Can I replace the 48MHz clock for a clock of 24.576MHz or 49.152MHz once I won't use the Bluetooth???

  • 0 in reply to Ryan Brown1
    Intellectual 285 points

    Hello Ryan

    I think the topic 833683 is related to audio transmission over bluetooth link. My project won't use bluetooth.

  • +1 in reply to Mariano
    TI__Guru* 99560 points

    Hi Mariano,

    - The I2S driver has not been tested for SCK frequency higher than 4MHz. I would suggest to run a few tests to see if with your HW design you could manage to run with an higher frequency.

    - The system won't work if you change the HF crystal to a non-24HHz frequency. However, assuming you are using an external clock generator, I am not sure this would be required.

    With all that being said, I am not sure the PLL1700 is the right device for your application. First, the PLL1700 is not recommended for new designs. Second, the PLL170x series require a 23MHz clock input. This means you'll require one more clock source.

    To finish, I would recommend to use the LAUNCHXL-CC2640R2 and the CC3200AUDBOOST to run a few tests. As you will see, the CC3200AUDBOOST has a TLV320AIC3254 that can be used as a PLL.

    I hope this will help,

    Best regards,