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Sample recording: can it be done?
#1
So the MCU on the NerdSeq appears to be https://www.microchip.com/wwwproducts/en...2048EFH144 .

Notably, this chip has several fast (18msps, for a Nyquist cutoff at 9,000KHz) ADCs built in.

Looking briefly at the PCB, it seems at least the first analog input is connected (didn't look for the others) to something - it disappears down a via, but there are ground planes adjacent to it so it shouldn't just be grounded.


Are the ADCs connected to the CV inputs? Would make sense.

If so, can the input filtering / level shifting circuitry operate at audio rate?

If it can, then does anything else prevent a NerdSeq from live-recording 12 bit samples? (Presumably, RAM would have to be pre-allocated before recording, but other than that...)

Being able to do sound design with my modular, record into a sample, and then use that sample seems like a pretty amazing workflow- right now that seems to require either getting a PC in the loop (yuck!), using an external, pricy module to record and then swap the SD card from the recorder into the NerdSeq, or an even pricier module like the BitBox + the More Triggers expander.

(On a related hacking note - looking at the datasheet for that MCU, there's an external bus interface that supports pretty hefty amounts of SRAM. Might have to see if I can't break out the ol' bodge wires and make a More Sample Memory expander...)
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#2
(02-12-2020, 06:15 PM)Mimir Wrote: So the MCU on the NerdSeq appears to be https://www.microchip.com/wwwproducts/en...2048EFH144 .

Notably, this chip has several fast (18msps, for a Nyquist cutoff at 9,000KHz) ADCs built in.

Looking briefly at the PCB, it seems at least the first analog input is connected (didn't look for the others) to something - it disappears down a via, but there are ground planes adjacent to it so it shouldn't just be grounded.


Are the ADCs connected to the CV inputs? Would make sense.

If so, can the input filtering / level shifting circuitry operate at audio rate?

If it can, then does anything else prevent a NerdSeq from live-recording 12 bit samples? (Presumably, RAM would have to be pre-allocated before recording, but other than that...)

Being able to do sound design with my modular, record into a sample, and then use that sample seems like a pretty amazing workflow- right now that seems to require either getting a PC in the loop (yuck!), using an external, pricy module to record and then swap the SD card from the recorder into the NerdSeq, or an even pricier module like the BitBox + the More Triggers expander.

(On a related hacking note - looking at the datasheet for that MCU, there's an external bus interface that supports pretty hefty amounts of SRAM. Might have to see if I can't break out the ol' bodge wires and make a More Sample Memory expander...)

Hehe... and no :-)
The ADC of the micro haven't been stable and were erratic at the time i started with the first hardware, so i choosed an external ADC.
The inputs are DC coupled and only allow 0..10 Volt, so any audio signal would only have the upper half of the signal.
The audio signals would need to be additionally normalized/coupled to have 5 volt at the zero position. Beside that it is of course possible, but not planned at all. There is enough other cool stuff and an external sample module (with high quality audio and plenty of memory) makes much more sense than hacking some average samplig into it.

By the way.... External Bus was erratic when i started with the first prototypes....and it is actually 'pin used' already as a parallel port for the display Smile
So no chances here either :-)

The only option is then a sample expander (which was requested). But also here i don't think i will make it. They are great sampler modules out there which already do the job better than i would be able to do it as a side project.
PLEASE use the search function if something have been asked or discussed before.
Every (unnessesary) forum support means less time to develop! But of course, i am here to help!  Smile
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