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ADMP441 clipping

Question asked by slal on Aug 6, 2013
Latest reply on Aug 7, 2013 by slal

Hi all! I know this topic has come up in a few other posts, but I want to clarify a few points about the ADMP441.

I have an ADMP441 directly connected to an STM32F4xx ARM Cortex-M3. I have configured the MCU I2S peripheral to capture Philips I2S standard, 16 most significant bits extended to a 32 bit word, which means the most significant 16 bits of the ADMP441's output should be captured.

I notice heavy clipping in the audio I capture. Furthermore, if I right-shift the 16-bit PCM samples by 4 bits (divide by 16) I notice that the clipping reduces quite significantly, which doesn't make sense as dividing samples has no effect on the phenomenon of clipping in the microphone.

What are known possible causes of this clipping I see? Anything specific to board layout? Pads? Tracks? I2S bits being missed? I am quite confident that I am correctly capture all 16 most significant bits of the PCM samples.