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Digilent Pmod I2S2 stereo


maziiz

Question

I am using pmod i2s2 and it is working fine with transmission data ,

Now I need to use it as a RX from an external mic I use this converter to use my normal headphone for both mic and speaker, 

and Iam trying to loop back the data I recorded , I use MCLK = 25 MHz , LRCLK = 48.8K hz , SCK = 3.128 Mhz   (and these clocks are configurable)

but I donot hear anything of the recording data.
should I use an amplifier ?

or should I configure anything else other than the clocks

Pmod is operating as slave

Edited by maziiz
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Welcome to the forum!

Those clocks should be fine.

As mic hardware and line hardware are different, an amplifier is required. This why computers use two ports. The converter you linked only splits the cable, and does not appear to do any kind of amplification. Mic to line amplifiers are available for purchase online, but I do not have any specific ones to recommend.

-Arthur

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On 9/15/2019 at 3:15 PM, maziiz said:

I use MCLK = 25 MHz , LRCLK = 48.8K hz , SCK = 3.128 Mhz 

LR clock seems to be wrong. This should be the half i think, since it toggles with the 32 bits of a word indicating the same channel (L).
for MCLK some devices requires 128xLR Clock, some 256x.

For those reading the thread:

I recommend to use an appropriate audio clock, which can be achieved with a PLL like this:

PLL 1 : 100MHz -> 2:8 -> 25 MHz

PLL 2: 25 MHz >  29/59 ->  12.288 MHz   which is only some ppm away from the ideal frequency.

The resulting Frequency should be :  LR Clock 96kHz   / MCLOCK 12.288 / 25.576    - Sample FR = 48.000.xx  kHz

Leaving PLL 1 away would be appropriate für 96kHz / 192kHz Audio.

 

Edited by engi
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