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Change LRCK and BICK sample frequency of PCM5100

Other Parts Discussed in Thread: PCM5100, PCM5100A

I have a PCM5100 and I need to change the word (LRCK) and bit (BICK) clock sample frequency to match the master componet. I've tested the PCM5100 and it work correctly when using a PC as audio input and I was able to hear the audio from the speaker connected to the DAC. However when I try to connect the master component (BT module) of my circuit using PCM interface I get digital signal to the DAC input but no analog output. I've compared the sample frequency of LRCK and BICK of the DAC when working with PC and with BT module and the frequencies are different. According to the datasheet of the PCM5100 it should support the frequencies below:

LRCK 16KHz

BICK 256KHz

I need to know how to change the sample frequency of the PCM and make this work with my circuit.

  • Hi, Jun,

    Welcome to E2E and thank you for your interest in our products!

    Could you provide more information about the clock frequencies? Which clocks frequencies are used when the PC is used as audio input and when the BT module is used?

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.
  • Luis
     
    Per your request, here are the frequencies used.
     
                    PC                           BT Module
    LRCK      44.1KHz                16KHz
    BICK       2.8MHz                 256KHz
     
    Regards,
     
    Jun Kakeno
    Fujitsu Ten Corp. of America
    30155 Hudson Dr. Novi, MI 48377
    Mobile: 734-386-6478
    Desk: 734-414-6618
     
     
     
     
  • Hi Kakeno-san,

    The relation for SCK, BCK and LRCK is shown as below.
    So, could you please confirm the SCK frequency ?
    In addition, PCM5100A cannot accept the BCK rate(fs x 16) of BT module, then please change the BCK rate based on the audio data bit length if possible.

    Best regards,
    Kato

  • Kato-san
     
    Thank you for your quick response.
    I’m a little confused as to how to read the chart below.
    Could you please help me understand?
     
    My understanding of PCM parameters is PCM audio is coded using a combination of various parameters.
     
    Resolution/Sample Size
     
    This parameter specifies the amount of data used to represent each discrete amplitude sample. The most common values are 8 bits (1 byte), which gives a range of 256 amplitude steps, or 16 bits (2 bytes), which gives a range of 65536 amplitude steps. Other sizes, such as 12, 20, and 24 bits, are occasionally seen. Some king-sized formats even opt for 32 and 64 bits per sample.
     
    Byte Order
     
    When more than one byte is used to represent a PCM sample, the byte order (big endian vs. little endian) must be known. Due to the widespread use of little-endian Intel CPUs, little-endian PCM tends to be the most common byte orientation.
     
    Sign
     
    It is not enough to know that a PCM sample is, for example, 8 bits wide. Whether the sample is signed or unsigned is needed to understand the range. If the sample is unsigned, the sample range is 0..255 with a centerpoint of 128. If the sample is signed, the sample range is -128..127 with a centerpoint of 0. If a PCM type is signed, the sign encoding is almost always 2's complement. In very rare cases, signed PCM audio is represented as a series of sign/magnitude coded numbers.
     
    Channels And Interleaving
     
    If the PCM type is monaural, each sample will belong to that one channel. If there is more than one channel, the channels will almost always be interleaved: Left sample, right sample, left, right, etc., in the case of stereo interleaved data. In some rare cases, usually when optimized for special playback hardware, chunks of audio destined for different channels will not be interleaved.
     
    Frequency And Sample Rate
     
    This parameter measures how many samples/channel are played each second. Frequency is measured in samples/second (Hz). Common frequency values include 8000, 11025, 16000, 22050, 32000, 44100, and 48000 Hz.
     
    Integer Or Floating Point
     
    Most PCM formats encode samples using integers. However, some applications which demand higher precision will store and process PCM samples using floating point numbers.
    Floating-point PCM samples (32- or 64-bit in size) are zero-centred and varies in the interval [-1.0, 1.0], thus signed values.
     
    Table 2

    ·         How is BICK rate different than BICK sample frequency?

    ·         Is data bit referred to word length?

     
    Table 10

    ·         What is the sample frequency (vertical column) referring to? LRCK or BICK?

    ·         What are the numbers in the middle column referring to?

     
    I’m not using the system clock pin on the DAC.
     
    I’ve attached some test results I’ve done yesterday for your reference.
     
    No
    BT(master)
    DAC(slave)
    Communication
    Results
    Comments
    LRCK
    Word Size
    BICK
    LRCK
    Word Size
    BICK
    1
    16KHz
    8bit?
    256KHz
    unknown
    unknown
    unknown
    PCM
    X
    No audio signal present at DAC output
    2
    44.1KHz
    8bit?
    256KHz?
    44.1KHz
    unknown
    2.8MHz
    I2S
    Voice from far-end phone heard cut from speaker connected to DAC output
    3
    32KHz
    8bit?
    256KHz?
    44.1KHz
    unknown
    2.8MHz
    I2S
    O
    Voice from far-end phone heard from speaker connected to DAC output
     
    Regards,
     
    Jun Kakeno
    Fujitsu Ten Corp. of America
    30155 Hudson Dr. Novi, MI 48377
    Mobile: 734-386-6478
    Desk: 734-414-6618
     
     
     
     
     
  • Hi Kakeno-san,

    Please see my comments below :

    <Table 2>
    - How is BICK rate different than BICK sample frequency?

    ---> Please refer to figure 14 since the relation for BCK and LRCK is mentioned on page 16 of the data sheet when using 4-wire I2S.

    - Is data bit referred to word length?

    ---> Yes, your understanding is correct.


    <Table 10>
    - What is the sample frequency (vertical column) referring to? LRCK or BICK?
    ---> The sampling frequency(vertical column) means LRCK.

    - What are the numbers in the middle column referring to?
    ---> SCK is needed as the system clock when using 4-wire I2S, however the internal PLL of a PCM5100A supplies a SCK when using 3-wire I2S.


    Please refer to table 11 which is mentioned on page 25 of the data sheet if using 3-wire I2S.
    Unfortunately, the conditions which isn't mentioned in this table isn't guaranteed to meet the specification even if PCM5100A works normally.
    The following post will be helpful.

    https://e2e.ti.com/support/data_converters/audio_converters/f/64/t/532354

    Best regards,
    Kato