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Two AD1938 in daisy chain with ADAU1452


I am trying to connect two AD1938 in "daisy chain" mode to one ADAU1452 DSP, but I am stuck... 

The first thing I want to do is to config the hardware registers on both codecs so they can work in "daisy chain". For that I am using USBi and Sigma Studio (SPI). 

USBi is properly connected and detected by Sigma Studio. I am using SPI, so MISO, MOSI, SS and SCL are used between USBi and AD1938. Also, 5volts are provided to the codec. 

When I choose "Get Current Settings from Chip" all AD1938 settings go to default (all muted, disabled, power down, etc.). After that I modify all the settings and choose "Write Current Settings to Chip". Everything seems to be written to the chip, as my capture screen shows the blocks write, and "Downloaded" is shown on the right bottom corner. So far so good.

To verify that settings where written to codec, I now set  "Get Current Settings from Chip" , which should show all the settings I made previously, but instead all goes -again- to default (all muted, disabled, power down, etc.).

When trying this, I am not connected to the DSP, only to the codec.

Any clues what I am doing wrong? 


  • Hello mga2009,

    First DO NOT tie the resistor to 5V. MAX is 3.3V on this part. 

    It is the CLATCH pin that you have to pull up.

    You must have this resistor there to avoid entering the StandAlone mode when you do not want to. You can still possibly enter this mode if you hold all the control lines low for too long. I explained all this earlier.

    From your earlier questions:

    Yes, shutting off the power will be a hard reset. But there is also a reset pin which is also a hard reset. 

    3-. This is not my PCB design. Is there a way to mitigate this design problem (and have better noise floor) without redesigning the PCB?

    Basically No. There might be a few things like tacking in a few caps or shorting a few ground planes to help a little but it is difficult to fix in that way. Kind of like trying to make a race car out of a cheap small production chassis. 

    Now this thread has been going on for a while now. It would be good to reconnect with the actual problem you are having?

    Dave T

  • Dave, 

    Thanks for your help. 

    Still IDK you to properly load the config file from the DSP to my CODEC. 

    I managed to get the codec sequence file using Master Control Port in my SS schematic and properly downloaded to the DSP.

    I am using MP13 for control port.

    Now, I understand this is the basics, but still I don't get it.

    So, my MP13 is my control port, so I have to connect it to my CODEC pcb... but to which pin? Any other pin (besides the control port) is required for this programming?

    My understanding (informed guess), as I am using SPI on my master control, is MP13 goes to CODEC MISO, DSP CS goes to CODEC SS, and DSP SCL/CLK goes to CODEC SCL

    Sequence File