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Posts: 1
Registered: ‎02-20-2017

USB interface to I2S microphones

I am looking for a way to interface a dual microphone to a PC using high speed USB. I can convert the mike's PDM interface into an I2S interface, and there I am stuck. Does anybody have a suggestion for a simple (ideally single chip, minimum programming) solution? Thank you.

Posts: 2,384
Registered: ‎10-14-2014

Re: USB interface to I2S microphones

@yishai

Are you searching a product that support high speed (480Mbit/s)?

Here you have 2 separate microphones, after you convert it to I2S, you have 1 I2S interface or 2 for these input data? How about the format of your I2S data after you convert the PDM data?

 

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WeiguoLu
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Posts: 472
Registered: ‎01-18-2004

Re: USB interface to I2S microphones

[ Edited ]

yishai wrote:

I am looking for a way to interface a dual microphone to a PC using high speed USB. I can convert the mike's PDM interface into an I2S interface, and there I am stuck. Does anybody have a suggestion for a simple (ideally single chip, minimum programming) solution? Thank you.


Two comments:

 

  1. For a dual-microphone setup, even with sampling rate set to 96 kHz and using 24-bit data, you don't need High Speed USB. Full Speed (the 12 Mbps flavor, often mistakenly referred to as "USB 1.1") is sufficient. Why does this matter? Audio on High Speed USB requires USB Audio Class 2.0, which is somewhat more complicated than UAC 1.0. And if you're on Windows, you need a UAC 2.0 driver, as one is still (over ten years after the class was published by the USB people) not native. For Mac and Linux users, a native driver is provided. That said, using the 2114 for Full Speed USB audio at 48 kHz (24 bits if using the B02 variant) as fed from an audio ADC is fairly trivial.

  2. Silicon Labs doesn't have any USB devices which support High Speed. It would be lovely if they offered a flavor of the 2114 which supported High Speed USB so it could support multi-channel audio. And there are no real simple minimal-programming solutions for High Speed USB audio. The XMOS devices come close.