spdif src dc offset.

alex239 Question

Mar 6, 2019 00:00

i use adau1452.

problem

when i start the program asrc give dc offset. when i put spdif signal it becomes to 0.

its only for first start.

i dont want to use dc block/ i think it can be solved in registers.

Report

DaveThib Reply

Mar 7, 2019 00:00

Hello alex239,

This is happening because with no clocks coming into the ASRC, there is no data being clocked in. So therefore all the memory has not been cleared and it is only putting out one random value.

There is a way to do this within the program but first, If you have a controller you can change the input of the ASRC to an input that has clocks and wait long enough for the memory to clear then switch it to the SPDIF input.

I will attach an example project that will monitor for the ASRC to lock. If it is not locked then the volume control has the audio shut off. As soon as it locks the volume control is turned up to unity gain. There is a look-ahead delay so make certain that the volume control has time to slew down before the loss of audio arrives at the volume control.

So this will give you an idea on how to do it. You will have to adjust the DC cell to mask the correct bit for the ASRC you are using.

ADAU1452 ASRC Lock Detect Example.zip

Let me know if you have more questions.

Thanks,

Dave T

ADAU1452-ASRC-Lock-Detect-Example.zip28.6 KB

Report

alex239 Reply

Apr 13, 2019 00:00

thank you. problem solved.

Can you sugest proper working on 192.

i try to start 1452 on 192.

24 576 crystal.

pll devider 8

start clock x4

. what to do with input output. they still on 48 khz.

Report

DaveThib Reply

Apr 29, 2019 00:00

Hello alex239,

You need to set the serial ports to the higher rate.

Look at figure 20 on page 38 of the datasheet.

These settings are on the Serial Ports tab of the register controls page of SigmaStudio.