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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,

    Can you supply some details of the hardware? Schematics would be helpful and so would your SigmaStuido schematic. 

    How are you connecting the USBi to the codec? The USBi 10-way ribbon only has one SPI latch so you have to wire up some more to talk to the codecs. Also, you need to set it all up correctly in SigmaStudio. There are so many ways this can go wrong that I need all that info to quickly eliminate possible causes. I do not want to write many long posts guessing. 

    What you are seeing is telling me you are not "talking" to the codec at all. The bad thing with SPI is that there is no handshaking so when you send commands you have no way to know if they were actually received. So when you read it back all you get is zeros. Nothing is answering your request. 

    It may be something simple. 

    Dave T

  • Here is the scheme of the codec and the USBi.

    Sigma Studio Project

    Attached is a very basic prototype of my SS project with a very basic XML sequence for the Codec. 

    I am connecting the USBi to (1x) codec using pins sing SPI, so MISO, MOSI, SS and SCL.

    Dave, once again, thank you very much for your invaluable help! (and incommensurable patience!!)



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