PCM2903C USB Audio Codec Alternatives & Experiences

[For The Popcorn]

I'm working on an audio sensor interface to to smart phones to allow the array of phone app "test equipment" to be used. My initial thought was to use a cheap USB dongle for input (because phones are less and less likely to have an audio jack and to prevent damage to a phone), but these dongles only have a mono mic input; line inputs on small (& cheap ) dongles don't seem to exist.

So, typical of scope creep, adding an audio codec seems like a better route to take. The Texas Instruments PCM2903C seems like a good option. Stereo line inputs and not too many external parts required. Does anybody have experience with these chips or similar chips (basically a sound card chip that handles the USB connection)?

The PCM2903C is self-powered. For my test version, I had hoped to power a board from USB, but the '2309C requires power before making the USB connection. Other functions of my board will ultimately require battery power, but I was hoping to avoid that for my test board. The PCM2902C is bus powered which would be ideal for the test version, but its (fixed?) USB descriptor only requests 100mA.


One other question for anybody familiar with these chips - a number of profiles are supported. Stereo or mono, sample rate, etc., but no methods of selecting these is specified. I assume this is set on the USB host device?

I appreciate any suggestions, but I'm looking for a self-contained device to go from audio input --> USB interface.

 

[rjenkinsgb]

Is it a one-off or a production design?

There are lots of different USB "Sound card" units that have a full set of stereo connections & some are quite cheap, eg.

https://www.amazon.co.uk/LEAGY-External-Surround-Recording-Compatible/dp/B07DGR9M6M/ref=sr_1_5?keywords=usb+line+in+adapter&qid=1706853019&sr=8-5

And probably far less than that at Aliexpress..

If it's anything to do with audio quality testing for a one off, a cheap audio interface for music could be a good option, such as a Focusrite one? They have excellent noise and distortion characteristics.

 

[For The Popcorn]

Thanks. I've seen similar "boxes" but they are prohibitively large for my application.

My concept is to interface an industrial accelerometer similar to this type to a USB interface in order to use an FFT app one a phone – for a machinery vibration analyst, this beats dragging a large spectrum analyzer or data logger into the field for quick troubleshooting. I do have several other features in mind too, so there's already a moderate-sized circuit board required....with the goal being a pocket-sized device.

This would be useful to a pretty specialized audience but their might be a small market for it.

 

[rjenkinsgb]

OK.

SSS1629?? I have some Waveshare audio add-on cards for Jetson nanos that use those, they are categorically stereo in/out devices.

Datasheet:

http://www.3system.com.tw/upload//product/b7537e35a086a527ec39c95629987965.pdf

The texas ones look interesting, but the datasheet seems to lack a "complete" design; this one has a lot more detailed info & the device can be pre-configured using an I2C connection, by the look of it.

Even if you go for the Texas PCM2903C (with an external 3.3V regulator for bus power), the design details in 1629 datasheet may be helpful.

 

[For The Popcorn]

Wow, very interesting part! It's much more configurable than the TI part. I think most of the setup would be disabling features I don't want – please just digitize my signal with as little molestation as necessary It does look like it could handle some of my signal processing path, saving some parts.

I need to wade through the datasheet to understand all the features.

Thanks for the suggestion.

 

[For The Popcorn]

Hmmm. Many of the small USB dongles seem to use this part, possibly including the one I bought a few days ago. Apparently there's an app that allows changing some of the setup options. I wonder if the input can be changed from mic level to line level..... much studying to do.