ADAU1442 ASRC won't work at 192kHz

Hello jtuomy,

First, the SPDIF will not work at 192kHz. 108kHz is the max. So that is the issue with the SPDIF.

For the serial ports, They are capable of TDM4 at 192kHz fs. The ASRC is capable of an 8:1 ratio so you are fine there. What is most likely the issue is the PCB layout. That is a possible cause. How long are the lines?

So one thing you can try is to increase the drive strength. I am not sure who is the master. But the side that is driving need to have a high drive strength. Registers 0xE247, and 0xE248 are the drive strength registers for the BCLK and LRCLK in the DSP. It is very common for parts to have a weaker drive strength so keep the reflections down and RFI but when using a 24.576MHz BCLK you do not have much timing margin and must use a higher drive strength.

Feel free to take some screen shots of the BCLK, LRCLK and SDATA as close to the DSP pins as possible.

Let's start with this for now. I may need to see hardware schematics, PCB layouts and SigmaStudio schematics to help you find the issue. It may be several little things adding up.

Dave T

Thanks Dave!

As it turns out, the solution was really very simple. The hardware person had mistakenly specified Positive BCLK Polarity for the two TDM-4 Inputs we use. When the BCLK Polarity for both inputs was set to Negative, the problems with 192kHz and apparently also with problems with some Theatrical Movie playback were completely solved!

Thanks For your help!!

Jim Tuomy