AD1937 - Can I set ABCLK per frame to over 64cycles in I2S stereo mode?

song Question

Sep 30, 2011 00:00

Hello, AD engineers.

I am using AD1937 for recording and I am just checking ad1937 for what kind of BCLK and LRCLK I can use when I record.

I have several questions about BCLK frequency for ADC operation.

I set..

ADC test format is stereo, ASDATA delay is 1cycles, ABCLKs per frame is from 64 to 256cycles.

When I set ABCLKs per frame to 64cyles, the L/R data is coming out from AD1937 accoring to LRCLK ( L data is on low of LRCLK and R data is on high of LRCLK).

But when I set ABCLKs per fram to 128 or 256, both of L/R data is coming out on low of LRCLK. Should I set something else? or is it right operation?

In page 19 of manual, the note says "BCLK FREQUENCY IS NORMALLY 64xLRCLK BUT MAY BE OPERATED IN BURST MODE.".

It looks like giving some information about BCLK frequency and if I set BCLK freuqncy to 128 or 256 cycles, is it burst mode?

What is burst mode?

Thank you.

Songhee.

bclk

adc

Integrated/Special Purpose A/D Converters

Audio CODECs

burst-mode

ad1937

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ADIApproved Reply

Sep 30, 2011 00:00

Hi Songhee,

I don't think you can make the channel width greater than 32 bits. This is why you see the left and right channel come out on the first 64 clks in 128 or 256 bclk per frame. The 128 and 256 bclks per frame are meant for TDM operation where you want to have 4 or 8 channels of audio per frame. Hope this answers your question.

Best Rgds,

Alan

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song Reply

Sep 30, 2011 00:00

Hello, Alan.

It seems like it supports 64fs, if it is bigger, it becomes TDM format automatically.

I thought that I can set bckl-per-frame to 64fs, 128fs and 256fs so I tried to use I2S stereo with variable bclk frequency.

Thanks.

Songhee.

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