4 CVs From Arduino! (DIY Eurorack Tutorial)

How to send 4 voltages (12-bit resolution) from Arduino! We can use MCP4728 to do so!
This will allow us to create custom CV generators or to control modular synth parameters using sensors!
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Music by / bootyjazz
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What to Buy
-MCP4728
www.adafruit.com/product/4470
www.amazon.com/Adafruit-4470-... (twice the price tho!)
-Cable Jack
www.amazon.com/Aike-Plastic-S...
-Breadboard + Cables
www.amazon.com/Standard-Jumpe...
-Arduino
www.amazon.com/Arduino-A00006...
-MCP4728 Tutorial (easy to follow if you have watched my previous tutorials)
learn.adafruit.com/adafruit-m...
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Social Media (please feel free to share your projects!):
/ takumi_ogata
/ takumiogata
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0:00 - Intro
0:52 - Synths Used
1:11 - MCP4728 DAC
1:45 - Code & Testing
2:09 - Let's Test It On Synths!
2:29 - Pitch
2:59 - VCA (Volume)
3:27 - Filter
3:55 - All 4 CVs At Once!
4:21 - Ambient Example & Outro

[@SoundSimulator]

Don't worry about the yellow cable on the Arduino by the way!! It was for the MIDI tutorial and I forgot to take it off for this video. I'm sorry about the confusion. MIDI tutorial: kzbin.info/www/bejne/nZmTmWikeLxlnMk Again, please take your time and be careful with this tutorial because modular synths are expensive!

[@eigalabel]

Thank you! I watched the MIDI tutorial again and realised you recommended the Leonardo board for the MIDI project. Would the Leonardo board work as well for the application in this video, or it's better just buying the ONE and do the midi mod? Thank you again

[@deldridg]

This is a great vid and thanks for all the effort putting it together. In the past my son and I have messed around a bit with Arduino, and have written some raw PWM code where we can change the pulse width with a pot, or even oscillate it with some form of Sin wave (or stacked Sin waves => square/saw etc.) generation code. Now we're getting into some basic sound design, this is very exciting, though I'm using Softube's Modular rather than hardware and will have to work out how to get the CV into my DAW! Love a great challenge and big thanks mate from Sydney - Dave

[@SoundSimulator]

That sounds awesome! Thanks for sharing, Dave! Feel free to share a video of the project when it's ready//

[@anthonyniedzwiecki33]

Perfect timing with this video, thank you! I have a project I'm working on using sensors to interact with sound and am very new to arduinio. That module should be pronounced "unicursal" as in one line, as there is a unicursal hexagram pictured on the module, a hexagram drawn with out having to lift the drawing tool.

[@SoundSimulator]

Thank you so much for watching, Anthony! I'm actually editing a video where we use this Quad-DAC with sensors. Should be out in few days!! Ah, I didn't know about unicursal hexagram! That's really cool. I'll make sure to pronounce it as that next time!

[@brauliog7378]

Thank you for making this video! I'm trying to figure out how to make a trigger sequencer with arduino and this is really helping.

[@SoundSimulator]

Niceee, that sounds like fun!! Please let me know how the project goes//

[@norrin_sad2778]

Thanks so much for doing these videos! Very valuable and helpful info :)

[@SoundSimulator]

Thank you so much for watching!! I'm glad that these videos have been helpful to you!!

[@equalequalslopezcartoons3702]

So valuable thank you for all your work. ❤️‍🔥

[@SoundSimulator]

I'm happy to hear that this tutorial is helpful!! Thank you so much for watching!!

[@camicelestia3578]

oh heck yes I've been meaning to learn about this! thanks!!

[@SoundSimulator]

Awesome!! I'm glad you find this useful!

[@studiospiraluniverse]

$38.75 for shipping the DAC to Kuala Lumpur (Amazon and Adafruit same). Anyway this video is so inspiring again that I finally ordered.

[@SoundSimulator]

I'm sorry to hear that shipping can be quite pricey. At least the part itself is really affordable and I'm happy to know that you're getting one! This DAC definitely seems worth buying! We are going to explore more in the next two videos (and beyond)!

[@studiospiraluniverse]

@@SoundSimulator yeah this project definitely makes it worth the price. Actually I ordered two…shipping price is the same.

[@HumanMotives]

Great just what I was searching for. Thanks for the great explanation 🙏

[@SoundSimulator]

HAVE FUN~

[@HumanMotives]

@@SoundSimulator do you happen to have some sample code? I've read the DAC manual 10x times now and I can't figure out where I specify the source each DAC outputs. Where do I set that it uses my sensor data? Im a beginner programmer so all is hard :)

[@BlueSOF]

Thank you for the video! I suspect 12 bits of resolution is plenty for most applications. I’m curious about the test where you used white noise into a VCA to see how smoothly it affects the amplitude. I would be curious to hear you do the same test, but with a low-frequency sine wave, say 100 Hz, as that would clearly reveal any quantization or zipper noise in the ramp.

[@SoundSimulator]

Yeah! That would have been a great test. I can't guarantee that I will be able to do this any time soon, but I am curious now! Thanks for the suggestion.

[@joshbassett]

Great video, I have been following your projects with great interest 😁 I think using a 12-bit DAC for pitch is fine. I have a Sonic Potions Penrose quantiser module, which uses a 12-bit DAC, and it sounds great.

[@SoundSimulator]

Thank you so much, Josh!! Ah, that's good to know!! I should've included examples of 12-bit DAC in commercial modules!! I'm currently in the process of testing the resolution between two notes semitone apart! So far it looks promising!!

[@redwoodword]

If we simplify the maths by mapping 12 bit values to a 0-4volt range you get resolution down to 1 millivolt. 0.83 millivolts is 1 cent in the 1V/octave standard. So yes 12 bit for pitch definitely works.

[@hernanescudero6620]

You are awsome!

[@SoundSimulator]

Thank you so much, Hernan!!

[@lazarnikolic1222]

Great video. I was just wondering do i need to solder mcp4728 onto arduino uno?

[@SashaLattuca]

This looks fantastic! I'm gonna pull the trigger! Just a quick question from the beginner's point of view: I saw the DAC you're using has pins to connect it to the breadboard. On the internet, I found the same DAC without pins only. How can I adapt it to a breadboard? Thank you and keep doin'! :)

[@eigalabel]

Thank you for this great tutorial! The Adafruit MCP4728 QUAD DAC seems to be out of stock everywhere, can you recommend a substitute? Thank you again :)

[@SoundSimulator]

Yeah, lot of electronics parts are out of stock right now unfortunately. Hope it get better soon! In terms of a substitute, I don't know if there's one as far as I know. If you need to do this for school project that's due soon, you could purchase two MCP4725 and you'll have two DACs with one I2C. You could also create lowpass filters on breadboard and use PWM out of Arduino to have a decently non-noisy DAC. Otherwise, I would wait until they're back in stock!!

[@antimoustique3175]

Thanks for this video ! One question though, would this dac work to make an envelope generator ?

[@SoundSimulator]

Yep!

[@peaterrepeater4441]

Nice! I‘ve been thinking about porting a MaxMsp sequencer I made to arduino but I don’t have any experience with arduino. Would you know if there‘s a starter kit with all parts necessary, like you have it in this video? Tried to find one on the web but couldn’t find a one stop solution with breadboard, jacks and so on. Thanks!

[@SoundSimulator]

Next video I'm working on is actually on converting Max data to CV! I have links to the parts in the description. It looks like the breadboard + wire set is out of stock, so please check the description in this video kzbin.info/www/bejne/nKWnpaaJfbpli68 In terms of just sending data from Max, you really don't need much parts! I typically don't recommend the starter kit anyway. Also please avoid off-brand Arduino! There are a bit cheaper but I had people running into problems when trying to interface with Max or Pure Data. Have fun! And best of luck!!!

[@peaterrepeater4441]

@@SoundSimulator thanx for the reply, very looking forward to your next video!

[@dlvnmedia]

I was watching this on my phone and was wondering if you had the code examples somewhere that I could grab them and save them for when I get the parts in for this project? Waiting on a blank eurorack panel the MCP and a few other parts before I begin breadboarding and testing on my system.

[@SoundSimulator]

This video shows what you need to recreate! kzbin.info/www/bejne/jIq6gpSnm5usgpI

[@massimookissed1023]

A 12bit DAC gives 4096 different output levels. MIDI only has a 128 note range, so if the DAC's CV outputs only covered 128 notes, that's 32 steps (of about 3 cents) per semitone. Should be fine 😀

[@SoundSimulator]

Oh, that explains the 4095 = 5V in the code. Of course!! Ah, thanks for actually doing the math. Yeah, it's totally enough!!! This thing is such a gift to people interested in DIY Eurorack.

[@epsisphal]

Cool vide! Why using a DAC and not directly the analogue output of the Arduino?

[@SoundSimulator]

Good question! For using the analogWrite() is perfectly fine for LEDs and motors and such. But for audio, the signals can be too noisy! So, using a DAC like this becomes necessary for eurorack application. You could run a PWM through a lowpass filter circuit (which is not too difficult to set up actually) and get a decently clean signal (especially for VCAs). Tho, it's not the most ideal solution for pitch CVs.

[@epsisphal]

@@SoundSimulator Thank you for your reply. Interesting answer. I will have to try all this.

[@davidrysdam902]

QUAD DAC! I just bought a second single DAC. I wish I'd known there was a quad unit available.

[@SoundSimulator]

I experienced something similar too! I didn't know about it until I bought a dual DAC.

[@jonkruth4157]

Hi, could you maybe share the whole code so that MIDI USB also works!? Because the PC doesn't see the Leonardo as a MIDI device!? How did you do it? I just can't get any further. Thank you very much for sharing

[@GiuseppedeBenedittis]

Hi! Nice job =) have you tried to use 2 MCP4728 like a unique 8 DAC?

[@SoundSimulator]

I have been meaning to cuz it is possible! Just have a different I2C address on one of them and it should work :) I may do a follow-up vid.

[@GiuseppedeBenedittis]

@@SoundSimulator I think it's a little bit more complicate (at least for me😅) cause you will need to bit-banging the second mcp4728! Did you already make it? Can you explain me how? Thanks🙏

[@jonkruth4157]

I understand that it is only suitable for controllers...Can't you use it as an interface from the PC via USB/MIDI to the DAC to the Eurorack? Or is there a way? Thanks

[@siornejohn4056]

thanks! I am currently trying to pair this with the MPR121 capacitive touch sensor shield. I want to have have the touch sensor activate an envelope on touch, any advice?

[@SoundSimulator]

Yep! That should be possible! Just keep in mind as you search around on the internet that MPR121 and the Quad DAC are both I2C breakout boards.

[@TheOleHermit]

Just ordered the Teensy's quad audio DAC. But, it has capacitors on the audio outputs, so it's not DC coupled. So I'm unable to out DC offset voltages for RGB and positioning imagery. 🤦‍♂️ I'm also waiting for their 8 channel PCB, which I'll need to populate with SMD components, to have enough channels for XYRGB. 🤦‍♂️ So, unless I'm mistaken, you were outputting a DC ramp into the volume input of your VCA, using that inexpensive Adafruit's DAC?🤦‍♂️🤦‍♂️🤦‍♂️

[@SoundSimulator]

Didn't know Teensy has quad audio DAC! That's useful//

[@TheOleHermit]

@@SoundSimulator I forgot to mention that the Teensy has lots of DSP and filtering codecs. Their quad DAC communicates via I2C and passes audio over 16 bit I2S. The Teensy 3.6 has 2 DAC output GPIO pins, so a single stereo shield could be used to produce quad audio outputs, as well. The Teensy 4.x also has an 8in/8out audio DAC that uses multiplexed TPM. But, it's only an unpopulated PCB that uses SMD.😱 But, the gerber files and BOM is available to send to JCLPCB for mfr. Haven't crossed that bridge, yet. Just connected the Adafruit quad MCP4728 to my T3.6 on a breadboard to test it out. 😎

[@Rob_65]

12 bits is 4096 steps over 5 volts (5 octaves) this is 819 steps/octave or 1.46 cents/step. This is a difference you will not notice (at best it takes 3 cents on a pure note to detect a frequency change at C7, even more on lower notes) but the truth is in eating the pudding. I would get 2 oscillators with two CV values at the same voltage and tune them to be exactly the same. Not start changing one of the voltages step by step and listen. Most likely you will notice it is easier to get them in tune by changing the CV than by changing the potentiometer on the oscillator :-)

[@SoundSimulator]

Thank you for your insight! Yeah, I wish I had more modules (specifically analog) to test this with. I did notice that it was easier to set the pitch with CV than the on-board knob.

[@JoostMarkerink]

Are they also fast enough? I wonder how a fast sweep will sound.

[@SoundSimulator]

It's definitely fast! I'll see if I can sneak in a fast sweep demo in the video that I'm currently working on.

[@jonkruth4157]

Hi thank you very much for sharing..;) But i have a question: Is it posible to make one with another direction, to make cv to MIDI too?? it would be so nice to make one in both directions ;) Thanks !!!!!!

[@SoundSimulator]

That sounds like a good idea! I don't know when or if I can get to it, but I'll keep it in mind!

[@jonkruth4157]

Yes that souds very cool i would be very happy if you do so, and i think another people would too ;) i will folow you and looking for this sharing ...thank you very much for your work!!!!@@SoundSimulator

[@thestever]

What are the 10K ohm resistors used for? I don't see them in the video.

[@SoundSimulator]

Good point! I think I copy & pasted from a previous video and forgot to delete some stuff. Thanks for pointing it out!!

[@arideejay]

hi ! im super lost, wich code you use? and with the sensors, how do you connect the sensors and what code you use? thankyou

[@SoundSimulator]

I pretty much used the example code that comes with the library pretty much! As for using a sensor with this breakout board, I have a separate tutorial video :) It should be the one after this in terms of release date.

[@paolocolagrossi7632]

Hi! How are you sending CV to your Modular? Does the Laptop recognize the MCP/Arduino (once you upload the code) as a regular audio interface? Thank you

[@SoundSimulator]

Hi Paolo! Arduino itself is sending the CV via the MCP DAC. Laptop was used only for uploading the code and powering the Arduino via USB power. I could've powered it with AC adapter or battery and it would've been the same. If this is your first tutorial that you see on my channel, I recommend that you watch this kzbin.info/www/bejne/m4e6YXl6bsySic0

[@paolocolagrossi7632]

@@SoundSimulator Thanks for the answer. I’m interested to send CV through PD. I’m curious to know how would you manage serial data from PD in the Arduino code.

[@SoundSimulator]

@@paolocolagrossi7632 I'm currently working on a new tutorial covering that topic! Stay tuned!!

[@Moonpalacemusic]

unfortunately the MCP4728 seems out of stock everywhere. Do you know any alternatives to that? cheers

[@SoundSimulator]

Check DigiKey. There are still 26 left.

[@daghesan]

Hi! I am a total beginner at Arduino and electronics, so apologies for the noob question but how do I exactly connect the adafruit to the breadboard and Arduino? Is it soldered on the pins?

[@SoundSimulator]

If I remember correctly, we need to solder header pins to the Quad-DAC. I have a video on soldering. kzbin.info/www/bejne/bJrTlnZvmsefZ68 After that, check out my video on how to connect electronics around: kzbin.info/www/bejne/m4e6YXl6bsySic0 The tutorials that Adafruit provide for the Quad-DAC will be handy too. GOOD LUCK!!! The hardest part is soldering the Quad-DAC imo.

[@daghesan]

@@SoundSimulator Hi, thanks for the answer! I managed to solder the header pins to the Quad-DAC and the green light is lighting up, meaning there's current, I guess. The problem is that now I have connected the audio jacks and no current is coming out of it...I tried to wire everything as shown in your video, but I have no idea how to troubleshoot this! Can you help me with that?

[@SoundSimulator]

​@@daghesan It's still possible that there is not enough solder on the other pins. How are you testing that there is current going out? Are you connecting to a modular synth, LED, or?? Carefully re-wire everything. And check to see if you don't have any faulty wires, breadboard, and audio jacks (especially this one). Really examine the board. There are several possible solutions and it's impossible for me to guess over text. This is probably not the best tutorial for a beginner by the way, so you may have to take a step back and learn electronics basics. It's possible that you may be overlooking something that you learn in them. And I HIGHLY suggest purchasing a multimeter for trouble shooting. GOOD LUCK. It's totally worth the time and effort!!

[@daghesan]

@@SoundSimulator Hi, thanks for your answer! Yes I am testing with a multimeter and there is no current coming out. I think the soldering is the wrong part, since I am not good at it and I think that I probably should re do it. But thanks for your answer!!

[@SoundSimulator]

@@daghesan YOU GOT THIS!!! ✨

[@andrak5946]

Hey! Do you know where can I find some references on how to send CV from a modular synth to an Arduino without damaging it?

[@massimookissed1023]

Modular CV can be ±10v. Use a 6.8k and 2.2k resistors in series between your CV in and 0v ground. CV in >--[6.8k]--●--[2.2k]--0v The voltage at the ● connection between the 2 resistors will be 24% of the CV in, so about ±2.4v. You could use an opamp to add 2.5v to that, giving a range of 0.1v to 4.9v, and feed _that_ voltage to your Arduino's analog input.

[@jonkruth4157]

Hello, I've been trying for three days and it doesn't work. I'm slowly going crazy.... Please can you tell me how I can get my Leonardo to run as USB/MIDI together with the MCP47? I wrote the MCP example code, but the PC does not see the Arduino as a MIDI device. How do you have to write the code to make it work like yours? Please help me, I don't know what to do anymore!? THANK YOU

[@josezuniga3747]

Hey can some of these be daisy chained together? If so how would addressing each one go? And how many can be used at once?

[@SoundSimulator]

I think you can daisy chain them as long as the address is different between them. Your guess is good as mine tho since I haven't done it before yet. It's finally back in stock so I should grab another one. You can check the address in IDE but I'm not 100% sure how to change it. I need to do a follow up video covering that.

[@josezuniga3747]

@@SoundSimulator I would appreciate it if you could, the reason why I was wandering, is because I was wondering if 8 note polyphony could be achieved by taking midi data, and splitting it to several gates and cv, although you’d need a lot of output jacks. I know there are already a couple modules that can do that already but I was wondering if there were any diy options, and using several of these dacs and an arduino seemed like a plausible solution.

[@SoundSimulator]

@@josezuniga3747 Heck yeah! Arduino controlled DIY polyphony synth is definitely on the list of tutorial to make for the future.

[@massimookissed1023]

The MCP4728 has only one built-in fixed I2C address, it just doesn't have enough pins to select different addresses. However, the TCA9548 was designed for this purpose. It allows 8 separate I2C lines to be multiplexed out from 1 I2C control bus. TCA9548A modules cost about $1 on AliExpress. Adafruit also sell such modules for $7 You could have 8 x 4 CVs controlled by 1 Arduino.

[@mwatkins0590]

I was brave and plugged this into my mordax data. I noticed a problem - mine cant seem to get all the way up to 5V, they get to like 4.88 or something like that. This makes me concerned that things like pitch tracking would be off/wrong. I am using PJ398SM, which has 3 pins, one of which would be for normalling if it is unplugged (i just plug that pin into ground since its being used as output) - i dont think that would cause this but maybe? Any ideas how I could troubleshoot or fix this? I'm wondering if the DAC is just not very precise or if for some weird reason my arduino is messed up and not outputting a full 5v. I noticed if i touch the VA cable coming out of the DAC to my morax input that it is oscillating, like it will go up to 4.88 and dip way down, but somehow automagically when its wired through the jack it is steady.

[@massimookissed1023]

That DAC is quite precise, and when set to use "external Vref", it can output a voltage equal to its supply voltage. Check that the DAC is actually getting 5v supply. Reading the pdf for that chip, it shows the output voltage can be lower than intended if the input impedance it's driving (your Mordax) is too low. Try adding a 2.2k resistor between the DAC output and the Mordax input.

[@massimookissed1023]

The max voltage that DAC can output when using *"internal Vref"* and output gain of x2 is 4.096v. So you *_must_* already be using it in "external Vref" mode to be getting 4.88v :)

[@mwatkins0590]

@@massimookissed1023 hmm ill have to test it again this weekend, i could have been referencing the numbers wrong. Thanks for the tip.

[@lodwar]

I have a mmog mother 32. She wants some -5V to +5V to control. Anyone has some suggestions?

[@massimookissed1023]

That's gonna require some amplification. An opamp using Eurorack's ±12v supply could double the 0-5v output from the DAC, and provide the negative voltage offset to output -5 to +5v. The very common TL074 opamp is a quad opamp, so it would convert all 4 DAC CV outputs with just one chip.

[@axeman2638]

1, show us the output signal on a scope please. 2, what voltage range do you get out of it? is it bi-polar? aren't you going to just get 0 - +5v range?

[@SoundSimulator]

I need an oscilloscope for sure. I might purchase one after I buy a 3D printer. Haven't used on since undergrad tho... I gonna need a refresher.

[@massimookissed1023]

The MCP4728 can output from 0 to 5v (5.5v if you're feeling brave.) After that, you're gonna need an opamp running off Eurorack's 12v supply to get higher than 5v.

[@axeman2638]

@@massimookissed1023 eurorack CV signals are -10v - +10v

[@massimookissed1023]

@@axeman2638 they _can_ be, but that voltage range is more common for the sound signals than for CVs. At 1v per octave, a 10 volt range will go from sub-bass to higher than a mosquito on mushrooms. Anyway, Eurorack has ±12v supply rails, so opamps can be used to rescale any input voltage to that ±12v range. In the case of the MCP4728 outputting 0-5v, a -2.5v offset could be added giving -2.5 to +2.5v, and then _that_ range could be multiplied by 4 to give ±10v.

[@axeman2638]

@@massimookissed1023 CVs are used for more than just pitch, for modulation you need bipolar signals and full range. would be nice if there was a single chip solution that gave the full range without having to add extra op amps.