XHRA-2HPA, Audio interface output format?

Technical discussions around xCORE processors (e.g. General Purpose (L/G), xCORE-USB, xCORE-Analog, xCORE-XA).
smiba
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Joined: Sat Nov 05, 2016 2:22 am

XHRA-2HPA, Audio interface output format?

Postby smiba » Sun Jan 29, 2017 10:17 am

EDIT: Self answering my question after I've successfully built the first prototype, the option on the WM8741 should be 11 (24-bit I2S).
Do NOT leave this floating, leaving any of the two HW pins to select I2S floating and the DAC will make the opamps output 8V loud distorted bullshit and WILL blow something without precautions

Hi,

Quick question about the audio interface output of the XMOS XHRA-2HPA as I need to configure my DAC for the proper input

I'm able to select between the following options:

PCM Audio interface mode:
00 16-bit right justified
01 24-bit right justified
10 24-bit left justified
11 24-bit I2S

Just to be sure, this should be I2S right?

Thanks!
Last edited by smiba on Mon Apr 10, 2017 5:40 pm, edited 2 times in total.
henk
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Joined: Wed Jan 27, 2016 5:21 pm

Postby henk » Mon Jan 30, 2017 9:33 am

That depends on your DAC. They serialise the data using BCLK and LRCLK, the different is in the alignment of the data relative to the clock.

Many DACs support multiple of those modes. The last mode, "I2S" refers to the mode where the data is one bit misaligned with LRCLK, the others are aligned but left or right in the word. DACs often support multiple modes. Check which mode your DAC supports by default, or set up the DAC over I2C (using the flash commands) to set it up correctly.

You can easily try which one is right; it will clip a bit, clip like mad, be a bit quiet or very quiet if you pick the wrong one!

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