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DIX9211: Interfacing i2s

Karsten Jarke
Prodigy 60 points

Part Number: DIX9211
Other Parts Discussed in Thread: PCM5122

I have 2 questions regarding i2s.

1. I would like to interface a Bluetooth module with a DAC via the DIX9211 (Bluetooth -> DIX9211 -> DAC). The Bluetooth module has an i2s output but no system clock output. What would be an appropriate source for the DAC system clock? I would also use the DIX to rout a couple of spdif signals to the DAC.

2. The next possibility is to use the DIX9211 as a signal source switch for an ADAU1701 DSP. The ADAU has an i2s master output and an i2s slave input. The serial clocks have to be synchronous with the system clock which is already provided by a crystal on the PCB I have. The bit clock output of the ADAU can be set to various factors of fs. My idea was to connect the bit clock output to the system clock input pin of port B. I could then connect the system clock of port B to the system clock of the main output port. The audio data of the main output port might come from a spdif source for example. Would this sync the clocks? I guess making sure that the LR clock of the DIX output matches the LR clock of the ADAU output would be impossible. I'm not sure if that would be required. I'm aware that the best would be to use the DIX to provide the system clock for the ADAU but unfortunately the PCB I have does not provide that option.

If 2 does not work I'll just use the analogue input of the ADAU.

Thanks a lot!

   

  • 0
    TI__Guru 64835 points

    Hello!

    1.)  When using the DIX9211 with a 24.576MHz crystal or external oscillator input it will act as the I2S bus master for the received S/PDIF input signals.  Does the DAC input S/PDIF directly along with having audio serial interface bus (I2S, LJ, RJ) inputs?

    2.)  We need to look into this question a little further and will get back with you but we agree it would be better to identify a single clock source master and to use it for the other devices. 

  • 0 in reply to Collin Wells
    Prodigy 60 points

    I think for the first scenario it would be best to use a DAC such as the PCM5122 which can create the system clock from a 3 wire I2S signal. This should allow me to connect the Bluetooth module to the DAC via the DIX without needing a system clock.

    That raises another question. Does the DIX main output port work without a system clock (on some MCUs the port clock needs to be switched on for the port to work)? Lets say I send the Bluetooth 3 wire signal to MPIO_C with the MPIO_C0 pin tied to ground. If I rout MPIO_C to the main output port then the DAC should see a 3 wire I2S signal with the system clock at ground. The PCM5122 connected to the main output port should then create its own system clock. If I select an spdif source the DIX could send the system clock to the DAC which should also work.