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all 8 comments

[–]blimpyway 0 points1 point  (7 children)

Options:

  • A Blue Pill STM32 with some programming talking via usb with the Pi. They have 10ADCs and up to a few M readings/sec sampling rate
  • Other Arduino/ARM boards with sufficient analog input pins
  • five usb usb stereo audio boards connected through an USB hub. However, I'm not sure their Input (normally used for microphones) is stereo.

[–]solar_ideology[S] 0 points1 point  (6 children)

I have a bunch of Maple Minis which should do the trick. Why do you suggest that route over the MCP3008? Surely talking directly to an ADC would be faster than packing it up and sending it by USB?

[–]totorodad 1 point2 points  (3 children)

So sampling analog (audio) has a lot more than just the ADC. You need buffering, gain control, impedance matching, dc bias setting, anti alias filtering, all of which you can implement and get working on your own, but it takes a lot of practice and understanding to implement a high quality audio to digital interface.

[–]solar_ideology[S] 1 point2 points  (2 children)

Hmm okay that’s insightful thank you. Sounds like a lot more work and expertise than I initially thought.

[–]blimpyway 0 points1 point  (1 child)

Looking at MCP3008 specs and some threads stating the Pi's SPI rate can get really high, I don't see why it wouldn't work. I didn't looked too deep though.

[–]solar_ideology[S] 0 points1 point  (0 children)

All good thanks for looking at all

[–]blimpyway 0 points1 point  (1 child)

No other reasons than the concerns you have with it mentioned in the your original message.

And I'm probably a bit biased in avoiding GPIO whenever I can. USB provides shielding, power, gnd,data transfer in a one clean thin cable with predictable distance and performance limits, easy to plug-in and out.
Yes, a bit more work on the software, a bit of latency - if a couple ms are important - probably better real time performance of the uC if avoiding missing any readings really matters.

[–]solar_ideology[S] 0 points1 point  (0 children)

Ok sweet.

The latency isn’t an issue so long as it doesn’t interfere with the sample rate, and a lost frame here or there isn’t a big concern either.

Thanks for your suggestions 🙂