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Problem with ADAU1452 and External SPI Delay @96Khz

Question asked by andrea.labhf on Apr 26, 2017
Latest reply on May 12, 2017 by andrea.labhf

Hello everyone,

I'm developing an application using ADAU1452 and Sigmastudio 3.14.

I'm trying to use External Delay Block but unfortunately it seems that there is no way to use that block with a system sampling frequency different from the standard 48Khz.

I'm using EVAL-ADAU1542MINZ on top of that I've soldered a 23LC1024-I/SN SPI RAM in place of the selfboot eeprom.


I've created a simple blank project with ADAU1452 with the standard register configuration and the standard system sampling frequency of 48Khz

Using this "default" configuration, all is working good and I'm able to achieve a delay of about 683mS (131072 bytes / 4 byte per per sample = 32769 samples).


If I switch the sampling frequency to 96Khz, or wathever different from 48Khz, the audio output of the board is totally corrupded as you can see in the attached picture.

I've tryed different settings of bitrate, maximum delay, actual delay, etc but the output signal still reproduce casual waveforms.

A particular case is that if I set both maximum and actual delay to 32769 samples, in that case the output not distorced but there isn't any delay applied.


Note that, when I switch the project from 48khz to 96khz, I configure all the necessary settings in sigmastudio:

ADAU Start pulse Register to Base_Fs x 2 (96khz)

SigmaStudio FS combobox to 96Khz than i use both "Set system" and "propagate" buttons.


In attachments you can find Sigmastudio project and some screenshot.


I hope that I'm doing something wrong or there is a "work-around" for that issue since we are approaching the production of a product that must work at 96Khz with External Delay. 
Unfortunately I've previously tested this features at 48Khz figuring that it would have worked also at 96khz (obviously with half the delay time).


Thanks and Best regards.


Ps: I'm not a newbie of SigmaDSPs, I use sigmastudio and ADAUs since 2010 and I have developed tenth of products using  ADAU1452, ADAU1446, ADAU1701, etc...