Eval ADAU1761 Dac problem

Hi-

I moved this discussion to the SigmaDSP community. Please continue the discussion here.

AndyR

EngineerZone Commmunity Manager

Faisal,

The serial port interfaces to the ADCs and DACs use the I2S protocol. They do not support SPI. SPI is a communications bus, whereas I2S is a serial audio data bus. They cannot be used interchangeably.

There is a separate control interface on the ADAU1761, which is an SPI interface. That can be used to read and write from the program RAM and parameter RAM.

In order to store audio data or play it back, you need to have an interface that supports I2S.

I'm not familiar with the AVR atmega32, but you might want to check with Atmel to see if there's a way to set up its interfaces in I2S mode.

Faisal, actually you may be able to set up the SPI port on the Atmel to emulate I2S. However, you need to make sure that it meets the exact timing specifications defined in the ADAU1761 datasheet.

Thanks to all,

now I have emulat I2S in my avr, and manipulate that data in matlab, but there is no voice instead of noise, alot of noise. my question is that,

Is it necessary to use LOW pass filter after ADC?

and when i send that data back to Eva-ADAU1761 pin(through DAC) then adau1761 will be in master mode or in slave mode?

if ADAU1761 work in slave mode to get data through DAC, then how much BCLK is needed? and please also tell me which setting i need in sigmastudio to get data through DAC and play it.

Regard

Faisal

Faisal, I'm a little confused. Which IC is the master on the serial ports? Is it the ADAU1761 or the AVR?

Dear,

my questions are ,

1) is it necessary to use low pass filter after ADC,

2)when I store audio data collected fron ADC(aduau1761's ADC) and store in memory, then what is the right way to play back that data, (with the help of ADAU1761 or any other software).

take care.

1) No, there's no requirement to have a low-pass filter following the ADC inputs.

2) If your AVR is the clock master, then you have to make sure it is providing master clock (MCLK), frame clock (LRCLK), and bit clock (BCLK) to the ADAU1761. In other words, the two devices must be synchronous. If the AVR is a clock slave, then the ADAU1761 has to provide master clock (MCLK), frame clock (LRCLK), and bit clock (BCLK) to the AVR. You cannot have a clock configuration where the AVR and ADAU1761 have separate MCLK sources.

Then you'll need to set up the ADAU1761's registers to match that configuration.

The GPIOs must be set in serial port mode.

You'll need to configure the Serial Ports to be either master or slave. Make sure the AVR matches the other settings such as BCLK/LRCLK polarity, BCLK cycles/frame, etc...

Here's master mode:

Your AVR then has to emulate I2S at the same sample rate as the ADAU1761. It must constantly provide LRCLK and BCLK, just like in the timing diagrams from the ADAU1761 datasheet.

You'll have to make sure the AVR meets the timing requirements as outlined by the datasheet.

You must make sure your AVR meets all of these conditions in order to make this work.

It would be very helpful if you could share scope captures showing the I2S emulation.

Hello,

dear i acheived I2Sprotocol through my avr ATmega32(8bit microcontroller) i captured every 24bits data at 8khz sampling rate and playit back, sound has little noise but well. i want to ask that is ther any proccessure to play I2s data in computer,

because when i save large stream of data in memory and then play it back, then i listen only sound of noise. i am so confuse where is problem, during capturing or in playing back, please give me some hints how i verify that my capture data is ok.

Faisal

Faisal, it's very difficult for me to help based on your explanation alone. Do you have any of the following?

Schematic, showing connections between ADAU1761 and your uC.

SigmaStudio project.

Description of clock rates, including what is master and what is slave.

Oscilloscope captures showing the I2S data stream.

The more information you can provide, the better I and the community will be able to support you.

hello,

dear my main aim is to store voice data in mmc card, for this purpose i am using adau-1761, atmega32(avr 8-bit micro-controller) and mmc card.

but now i am working on eval board, in my first step i defined my I2S protocol in my controller,and just loop back data though controller, it working very well,

but when i ignor one channel data and loop back another channel data(one is ignore and other is loop back), then there is lot of noise add with my voice, sound quality become very poor,

plz tell me the method of disable left or right channel DAC.because i thing the noice is due to unused of one channel. i am so confuse.

Take Care.

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