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Can I use external SPI delay in 4 outputs in ADAU1452?


I need large delay which is out range of 1452, so I think I must use external SPI delay.

What I wonder is if I can use one SPI RAM chip to make 4 outputs delay lines, every output use different address offset.

If I must use 4 chips to 4 outputs, can 1452 support this operation?  

  • Hello Foster,

    As of the writing of this post the current revision is 4.6. In this revision there are a few bugs in the SPI Delay cell. Some of these bugs have been fixed and I have requested some updates to the cell to improve its functionality. The bug fixes should be available in the next release which is looking like it may be in December. The feature update I am not certain if it will make it into the release. 

    To answer your questions. Yes, just use one SPI RAM chip and when you grow the cell it will automatically setup an offset in the SPI RAM for the delay memory. Right now I am not sure of the implementation of using multiple RAM chips. I do not think this is up and running at this point. 

    The limitation to the External SPI RAM cell when grown is that all delay channels will be the same length and have the same current delay setting. I am asking for there to be a different current delay setting for each delay channel. So that may be a limitation you will have that all four delay channels will have the same delay time. 

    One other thing to note is that there will be a limitation for sample rates and number of channels. What is the sample rate you plan on using?

    Dave T

  • Hello Dave,

    Thanks for reply, I use 48KHz sample rate.

    However, I need different delay time for each channel, it maybe not available at this moment. 

    I am considering to use SHARC instead of 1452, it's a big change in my project. 

  • Hello Foster,

    You can always determine the minimum delay and set that in the Ext SPI delay and then send the audio from that delay directly into a regular delay cell that uses on-chip memory. Then you can vary that one as needed for each channel. It will depend on the adjustment range and how long of memory is needed. Remember you can go up to the ADAU1466 if you need more internal memory. 

    Dave T