Question about ADCs and DGND (seed)

Getting Started
1

Hi there!

Recent (happy) owner of a Daisy seed here :slight_smile:

I’m seeing 100k pots on most schematics I’ve seen in the examples.
Is this the only value to be used for inputs? Or is there a setting in libdaisy that would allow me to use 10k pots (it’s just that I’ve a good amount of nice 10k ALPS that I want to use in my MCU-based projects).
I’d have assumed they work like with an Arduino where the value doesn’t really matter as it’s just relative.

Another problem is with the DGND. When it’s grounded I get a high-pitched ground loop (just reproducing the Osc example with exact same wiring). I’m not sure if I’m doing something wrong or there’s some issue with my Daisy. I’m quite confused.
I’ve seen a post about this issue (Questions about digital noise and grounding) tho I’m assuming this wouldn’t happen when following an example from the library.
Should I then just use the proposed solution with the extra TPA6132 breakout?

Anyhow, big ups Electrosmith! Quite excited to dive into the libraries when I’ve sorted the above!

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I can’t see why you couldn’t use 10k pots - in fact it looks like the field does (Hardware/ES_Daisy_Field_Rev4.pdf at master · electro-smith/Hardware · GitHub) through a multiplexer…

That said, as wired as a voltage divider there is a constant 10kohm x # of pots load across the 3.3va rail - so if you have “lots” of potentiometers, this can add up to a bit of current, something to keep in mind. The seed appears to use an LP2985 regulator for the 3.3va rail, which has a max out of 150ma - some of which is used by the codecs. For 10x 10K pots in parallel that would be a 1K ohm load, and 3.3v/1000 = 3.3ma… so unless you’re creating a giant board of potentiometers I don’t imagine there would be an issue…

Good luck!

1 Like
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Ahh ok! :slight_smile:
I don’t know why I didn’t check the Field schematics since it’s similar to what I want to build. Just wanted to make 101% sure I’m not blowing this beauty up.
Thanks!