CV IN and a knob in the same ADC

is it possible to have a CV input jack and a knob controlling the same parameter, both going in the same Analog GPIO pin?

Also, what would happen if I put 0-10v CV from my eurorack system to a Daisy Seed analog input? Will I fry the Seed or it will just stop reading cv once it goes above 5v?

Thank you

Hi mirko!

It’ll be better to have each signal going into its dedicated analog pin separately.

EDIT: If what you have in mind is that you want to add CV “to the knob position as if the Knob were a 0-5V signal”, then you can! Please reference that forum post as well as the Audio Inputs section of the Daisy Patch schematic.

Anything above 3.3 volt will indeed fry the analog input pin. What you could use is zener limiter (Zener Limiters) and/or voltage divider.
There’s also this approach of using op-amp that’s better (Designing Winterbloom's Castor & Pollux - Stargirl (Thea) Flowers in the “Control Voltage Inputs” section)

I thought the normal range which the CVin is able to handle is depending on Negative Power and Positive Power inputs. So it should be able to handle more then 3.3v before it gets fried.

For the Patch SM, what you’re saying is correct from my understanding.

From the Patch SM Data:

Since OP is building a project with the Seed, it’s safe to keep the signal below 3.3V

From the Seed Data:

I actually overlooked this part in the datasheet which explains that most pins on the Seed are actually 5V tolerant (I’m sorry about that).
But there are still pins that are 3.3V tolerant, so it’s good to keep everything between 0.0 to 3.3 volt.

So @mirko, if you’re interested in using CV inputs from eurorack, it might be better for you to use the Patch SM.


Hey Takumi, thanks for tidying things up. I thought the seed and the sm have the same values for that.

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So I can use the Daisy Patch or I can copy the Power management and the ADC inputs schematics from the Patch or from here:

Yes, referencing the Daisy Patch schematic and other Seed-powered modules would be a good idea if you’re doing anything with eurorack signal (audio and/or CV). Good luck!

this is helpful, thank you! This would be a useful inclusion to the pinout diagram as well.

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Good morning Takumi! Can I ask for more info on this statement? I’m wondering especially because it seems the Daisy Patch combines CV inputs and Knobs on a single pin?

Hey Justin!

Yes, CV is added to the knob position. The ADC Inputs section of the Daisy Patch schematic is a great reference.
This forum post/thread also explains it too: Daisy Patch Input CV voltage and Control Knobs - #2 by shensley

I may have misinterpreted OP’s question on this thread that they wanted to connect the CV input and knob to a single ADC in a more independent direct way (so without adding the CV to the knob position and such). It’s been few months, so I don’t remember exactly how I was interpreting the question, but I’ll edit that post to clarify more.
Thanks for bringing this up :slight_smile:

Thank you so much for your reply! I may have misinterpreted the question too, now that I review. Thanks for linking the other thread too, I try to comb the forums pretty closely to learn all I can, but I think I’d missed that explanation, which is awesome. Thanks again!

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