EVAL-ADAU1466Z - SPDIF Input

Hello Luke,

Please find the attached project where SPDIF in and out is configured at 48KHz. I hope your sample rate is 48KHz.

If you want the project at some other sample rate, then kindly let us know. I will create another one and send that over.

This attached project takes SPDIF input and sends it to serial output 0 (I2S out) and SPDIF output. An internal tone generator is also included in the input path, so that you can switch between your SPDIF input and an internal tone. It helps in debugging. Below is the schematic.

4152.SPDIF pass thru.dspproj

Kindly do reply if you need any clarification.

Regards,

Harish

Harish, Thank you so much!

Hi Harishgowtham nice example, thank you for sharing. I have two questions:

1) Is it possible to implement an AES3 multi-channel input using this SPDIF input\output.

2) Is it possible to run at 192KHz?

I have a project that I'm working on, it works with two channels and with sample rates from 12KHz to 96KHz. I'm using an Audio Precision APx525 analyzer. However, it doesn't work at 8KHz, 11.025KHz, 176.4KHz, and 192KHz. I'm more concerned with trying to get it to work at 192KHz then the other sample rates.

Thanks,

Alex

Hello Alex,

1) No, is the basic answer on AES3 multichannel. I assume you mean more than two channels.

2) Yes, and no,... Here are the details about sample rates. the sample rate of the SPDIF output is always the sample rate of the core. ( with the small exception if you send the SPDIF in directly to the out. ) So you have to setup the DSP core and the PLL to be able to set the DSP start pulse to the rates you mentioned. The 44.1kHz based rates will require a crystal that is 11.2896MHz which is 256x fs. Yes, you can set the M and N of the PLL to get close to the correct rate with a 12.288MHz crystal but it does not divide evenly so there will be more jitter but I am being super picky. We do show how to do this in the datasheet:

To continue the SPDIF sample rate conversation. The ADAU1452 is the Sigma300 core. After we released the part we did discover a mistake where we used an internal divided clock to drive the SPDIF section. So the ADAU1452 family of parts can receive 192kHz fs SPDIF but cannot transmit it.

When we designed the Sigma350 parts, this is one of the details we addressed and fixed. So if you want to use SPDIF at 192kHz fs you need to use one of the ADAU1467 family of parts. They have this extra register where you can select the System Clock/2 or the full speed system Clock.

Dave T

Hi DaveThib yes, I meant more than two. So, I would need an AES/EBU digital audio transceiver and then feed that out to one of the SDINs and then the SDOUTs back to it, as well as clocks. However, for my application using this SPDIF IN\OUT will be fine. Appreciate all the details about the sample rates!

By the way, I'm using an ADAU1466, my crystal is indeed 12.288MHz. I'm running the DSP at 96KHz sample rate and all the blocks in my project as well.

I plan on using the SPDIF out as a thru just sending the in directly to the out as you mentioned. So, then I should expect that to work up to 192KHz, but it's not, the out is only working up to 48KHz. Below is a picture of my settings. I can send you my project and schematics privately for proprietary reasons if you want to take a look.

Thanks,

Alex

Hello Alex,

amonge said:
I meant more than two. So, I would need an AES/EBU digital audio transceiver

As Dave said, the SPDIF interface in SigmaDSPs does not meet the AES3 professional specification. so, it isn't supported.

I can see in the pictures attached that your current sample rate is 96KHz. so, doesn't it work with the settings above which is 96KHz?

For SPDIF at 192KHz, you have to set this register like below.

How do you say that it doesn't work, is the audio not coming out or you are getting any noise in the receiver end?

You can send the project to me or Dave privately using PM, before that please send us friend request so that we can respond to your PM.

Regards,

Harish

Hi Harishgowtham ,

I apologize for the long delay in response I was attending to other things. I finally got back to this.

Harishgowtham said:
As Dave said, the SPDIF interface in SigmaDSPs does not meet the AES3 professional specification. so, it isn't supported.

Understood. If I convert an AES3 signal to SPDIF signal levels using a conversion circuit as explained in this post, it does work. ADAU145x AES/EBU - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone

Harishgowtham said:
How do you say that it doesn't work, is the audio not coming out or you are getting any noise in the receiver end?

I'm happy to report it is now working at 96KHz, it was a hardware issue in our circuit.

Harishgowtham said:
For SPDIF at 192KHz, you have to set this register like below.

I'm sending you my project on PM, please take a look.

Thanks,

Alex