ADAU1788 latency and writing your own functions in FastDSP


The ADAU1787/1788 has a very low throuput latency of 5us. Is this latency dependent on the number and what operations are in use in the FastDSP core? If yes, is there more data on how the latency differs?

Also, is it possible to write your own functions for the FastDSP engine?

Does the package require underfill when mounted?

Thanks for your support.

Best regards


Analog Devices

  • 0
    •  Analog Employees 
    on Jan 16, 2020 3:31 PM

    Hello Martin,

    The Fast Core will process 64 Bi-Quad filters every sample period. If you need less then it performs NOPs so the latency does not change at all no matter how many or few calculations you have in the FastDSP.  

    Using SigmaStudio you can write your own functions but not assembly code. Keep in mind this is not a general purpose DSP, it is basically a filter engine. It will only do functions in the FastCore that can be done with a Bi-Quad. Like volume, mute, Gain and of course filters. If there is a need for general DSP functions then you can send data to the slower running SigmaDSP core where you have a large library of functions to choose from. There are sample rate converters to get to and from the SigmaDSP. But this will add to the latency. Generally, to use the lowest latency, the audio runs through the fast core and the SigmaDSP core is used to adjust the filters and gain etc., of the audio in the Fast Core. This does not have to be done as quickly. 

    It is my understanding that underfill is not required. We would have put that in the datasheet. 

    Dave T