VS1003 IMA ADPCM recording: nose from SPI bus

Writing software for systems that use VLSI Solution's devices as slave codecs to a host microcontroller.
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VS1003 IMA ADPCM recording: nose from SPI bus

Post by ssuloev » Sun 2020-01-05 23:59

I am trying to record IMA ADPCM with VS1003 and my custom Atmega128-based device. My problem is that I am hearing a significant noise at the moments when a block is written onto SD card. While SCI and SDI select lines are driven high at the moments it looks like VS1003 is still listening to SPI bus.
Could you give any recommendations on how to reduce the annoying noise?
Please, look at the attached file as an example of recorded sound.
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Re: VS1003 IMA ADPCM recording: nose from SPI bus

Post by pasi » Tue 2020-01-07 11:20

SD cards consume a lot of peak current while writing. Do you have a separate power supply for the SD?

Also check the orientation of your microphone capsule. There can be a huge difference in the output level if the capsule is the wrong way around.
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