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EVM TAS5508-5142K7 with external i2s and no MCLK

Alessandro Crespi
Prodigy 30 points
Other Parts Discussed in Thread: TAS5508

Good morning,
given that I am new to this world, I'll tell you my problem.

I have an EVM TAS5508-5142K7 and I have to connect it to a BT audio module Bluecreation BC127 on digital output (PCM / I2S/SPDIF).

BC127                                           TAS5508 BOARD (CONN. J60)
PCM_SYNC (46) => WS           => (13) LRCLK
PCM_CLK (47) => BCLK          => (11) SCLK
PCM_OUT (48) => Data            => (4) SDIN1
GND (1)                                        => (1) GND
SPI_PCM # (45) is grounded

BC127 I2S is selected and configured in Master mode, Left Justified with 1 Bit delay, 16 bps with a Word clock (WCLK) at 44100Hz and a Bit clock (BCLK) at 2.822Mhz (64*44100Hz)

After having properly set the BT module for digital audio output (i2s) I still can not make play audio.

TAS5508 BOARD is connected to the INPUT-USB board with the J40 connector and to the PC with the USB cable.

The only connection I can not do is to (2) MCLK because the BC127 module does not support it, but the MCLK is optional for i2s ..

I mistake or forget something?

Grazie in anticipo e a disposizione per fornire maggiori dettagli

  • 0
    TI__Guru 57800 points

    Hi, Alessandro,

    Sorry for the delayed response, my colleague is working o this and will get back to you as soon as possible. 

    Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    TI__Mastermind 27850 points
    Hi Alessandro,

    While MCLK is not required for the I2S interface standard, this part in particular, and many others as well, require a synchronous MCLK to function. This is because in order to do its processing it needs a faster clock (at least 128*Fs) to run the internal processor. You could use a clock multiplier on the BCK signal and send the resulting clock (at least 128*Fs) to the MCLK pin.

    Justin
  • 0
    Prodigy 30 points

    Thanks Justin and Diego for the support,

    I now have a new problem ..

    Even using the usb input board in the kit, with both analog source or digital (optical input) and connecting the speakers, I always hear a background noise (Also on the headphone output).
    I thought it was due to the power supply, but also powering the whole system with battery , the noise does not decrease ..
    At this point I think it is a coding problem, or incorrect setting of the mixer outputs or a defect of the development board ..

    What should be the proper setup?
    Configuration parameters and speaker connection?

    Thanks again!