AIC3254+CC8530 : Click noise on the microphone input

Hi Bernard, 

Hard to say for certain here but a few questions to try to narrow this further down:
 - reduce the output power to the minimum (but do not select range extender none) for the slave side - any reduction or changes to the click?
 - "reverse" the slave and master roles for the two boards and see if behavior changes
 - does touching the mic connector on the slave change things? 
 - are the click frequent in period/time?
 - if you have access to the Headset SDK, could you try the same configuration there and use the same electret microphone?

Regards,
Kjetil 

Hi Kjetil,

It took a long time to answer due to holidays and a new routing of the board.

But now the "cjick" remains the same with the new board.

We have seen that the "clic" frequency is exactly 75 Hz and it appears as a pulse that is added to the main signal.

The 'clic" doesn't seem to be depending of the output power nor of any touch on the microphone.

Changing the decoupling of the board has no effect.

If you have some idea you are welcome.

Bernard

Hi Bernarnd, 

Tough one. If the click frequency is 75 Hz we can rule out any power pulling introduced by the RF protrocol (output power not having an effect indicates the same). 

Most likely this is picked up by the analog path prior to the AIC device. I'm not an expert in these devices but do believe these have a loopback option so that you can test just the audio/analog path on your boards to see if it becomes more obvious where the click is generated.

Might be helpful if you could record and post a short sample that includes the click but is otherwise silent. 

Regards,
Kjetil

 

Hi Kjetil,

Up to now i have some problems to see the power pulling and i didn't solve my deffect.

I made a creen caoture og the cjick that appear as a pulse reaching the 0V that is added to the main signal.

On the screen capture we see the ouput of the master in blue. I put a sinus signal on the microphone entry of 100 mV CC precisely at 75.00 Hz

At this frequency the clic is completely synchronous

I ll try some other experiments to find the signal on the board.

Thank you for help

Best regards

Bernard

Hi Ketjil,

A new information on my problem

It seems that my snapshot wasn't in my message so i try it again.

THe new information is that if i change the frequency from 48000 Hz to 32000 Hz the pollution pulse frequency step down from 75 Hz to 50 Hz

That means that the ration is constant equal to 640

If someone has a idea to explain that behaviour

Best regards

Bernard

Hi Bernard, 

Interesting information - could you also check if latency setting will affect the frequency of the click?

Another thing that would be interesting to know is if this disappears if you configure the master as a mono microphone base station.

Can you please send us the configuration files and configurator version number (including build id) as seen on the start panel? 

Best regards, 
Kjetil 

Bernard, 

One thing that can lead to periodic clicks like this or poor audio performance is (from the help system in the PurePath Wireless Configurator - troubleshooting):

Audio is heavily distorted in host-controlled operation, but OK in autonomous operation: Verify parameters used in the NWM_ACH_SET_USAGE EHIF command.

Regards, 

Kjetil

Hi Kjetil,

I have tried various latency but the pulse fréquency remains the same. It seems to be depending only of the sample rate.

I have also tried to change the ratio of BCLK with 32 or 64 with no change.

For information i use de PPWC 1.4.0.37396

I send the project files for information

Best  regards

Bernard

Hi Bernard, 

Thank you for that information. Please let us know when you have verified your NWM_ACH_SET_USAGE parameters (quickest might be to just operate the cards in autonomous mode). The periodic behavior that changes with sample rate bare signs that something potentially could be going haywire with our FW and want to rule this out or find the root cause so that we can fix any issue. 

Have been running several tests here in my office over the two days and have not found anything wrong nor do we have other reporting something similar, wrong NWM_ACH_SET_USAGE is the only explanation we can think of right now. 

Will run more tests when you have posted your project files - please share your code (snippet is enough) of the  NWM_ACH_SET_USAGE command so that we can look at the parameters vs. your project files. 

Regards,
Kjetil 

Hi kjetil,

Thank you for your interst to my problem.

For the use of the NWM_ACH_SET_USAGE, i have tried 2 configurations.

The first one was :

master / chapter audio streaming / master to slave / Front primary left + AD0 + right + SLAC

master / chapter audio streaming / slave to master / Microphone0  + AD1 + left + SLAC

The matrix sent for the NWM_ACH_SET_USAGE was 00 FF FF FF - FF FF FF FF - FF FF FF FF - 01 FF FF FF

The second one was:

master / chapter audio streaming / master to slave / Front primary left + AD0 + right + SLAC

master / chapter audio streaming / slave to master / Input Left+ AD1 + left + SLAC

The matrix sent for the NWM_ACH_SET_USAGE was 00 FF FF FF - FF FF FF FF - FF FF 01 FF - FF FF FF FF

The two configurations gave the same result.

As i tried some other possibilities for the NWM_ACH_SET_USAGE the result was directly no sound at all.

I didn't see if my file was correctly attached in my last post so i tri it again.

I will make some other  tests today and i will report you.

Best regards

Bernard

Hi Bernard,

Try the following vector:

00 FF FF FF FF FF FF FF FF FF FF FF 00 FF FF FF

This corresponds to the channel index you see in the configurator (see picture below):

Best regards

Kristoffer

Hi Kristoffer,

Thank you for your help

That is the right solution to my problem

It is amazing to see or hear  the bad effect of a 1 instead of a 0 in that register.........

I can now continue my project

Best regards

Bernard