#9

I bought a few to build with a while back, but that was almost a year ago now and nothing much done at all :pensive:

#10

http://bleeplabs.com/ has some (non-eurorack) Teensy projects, which I think are open sourced (Delaydelus, Thingamagoop 3000 (?))

Besides RM and NeutronSound, I’ve also built this: https://github.com/mxmxmx/O_C/tree/asr

(There’s more Teensy projects in that repo).

MacroMachines Omni I think is basically a Teensy. But I’m not sure it’ll be open-sourced.

Bastl seems to have something in the works (Take a look at their github). Difficult to tell what though.

If you don’t mind gcc/JTAG, the NUCLEO-F303K8 seems like a nice/cheap alternative. 3 DAC channels and it’s a M4F. I think (never tried), there’s a libMaple (=quasi Arduino IDE) port.

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#11

Just put together a video of my latest DIY project. Again it’s Teensy based. This time in the Eurorack format, making use of the Teensy Audio Shield. It essentially samples small sections of live audio and lets you manipulate them. https://www.youtube.com/watch?v=Wnd8HAyvk2A

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#12

this is great! you might want to consider moving power regulation onto the board - and also some reverse polarity protection…

(I got the boards for the prototype of the thing I mentioned waaay earlier in this thread back last week. first notes from the 0.1 code: it’s really fun. can’t wait to share more).

#13

aha - here’s a grab of what I’m currently working on:

ffc-shareable-2.jpg960×1280 161 KB

which came back from fab last week. Amazingly, it basically is already working in simple form, and now the real job is overhauling the firmware. I imagine it won’t be a Teensy forever: the code is mainly math and logic, so I think this is going to be an ATMega directly on the board, which will be a new adventure for me. Still. My first time sandwiching two boards and it all working OK.

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#14

Cheers! I wanted to keep the circuit relatively simple as it was the first time getting a pcb fabricated, so left out any power regulation etc. It’s just connected directly to the 5v line on the Eurorack power. Seems to work for my prototype needs. I might add it to the next version of the pcb, along with more jacks for CV input, although the Teensy Audio shield hogs a lot of the analogue inputs.

Will you be putting up more details of your project soon? Looks great!!

#15

eventually! I kinda want to have something like a 1.0, though, because the thing it’s doing is both relatively straightforward and yet… somewhat unique? I’d rather just go “here is a thing, it is done” than get a bit held up. It’s intended to ultimately be a DIY project, I think.

Good luck with your second version - more than happy to offer input/a hand. I reckon you can get several HP off that PCB if you’d like to, easily - there’s bags of space - and that’s before you put in power reg/protection. Although 5V from 12V is as simple as a regulator and a capacitor, pretty much.

More importantly, though, like I said, loving the sound and functionality as it stands.

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#16

Yeah, I could definitely do a more compact version of the PCB. I was just learning Eagle at time, man, that software has a steep learning curve! Cheers for the offer of help.

#17

yeah, EAGLE is… challenging. Having spent ages wrapping my head around it, I’ve developed a kind of Stockholm Syndrome - I’m actually rather attached to it now, and have got quite fast to the point it’s usually quite enjoyable. I describe routing as a really, really compulsive puzzle game, to people who can’t see the charm. I still learn new things in it every day, though - always trading tips with other DIYers…

As you’ve probably found, though, the easiest way to learn it is to have a friend to teach or answer questions - the documentation online is all quite spare.

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#18
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#19

Question for the Teensy experts.

I want to build this to interface Max + Euro. Is it possible to make modifications to the code to get more than just two CC/pitch outputs? Just duplicate the code given for A21/22? My ideal would be 8 outputs from which I can send CC from Max as CV to Euro.

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#20

A21 and A22 are the only analog pins on the teensy 3.6 that go through a DAC so I think if you need more than that you’d need to add some more circuitry. I don’t know enough to help with what that would look like though.

#21

yep, this is correct. If you want more analog outputs, you’re going to have to start adding more DAC chips to the circuit. DAC chips go up in price based on precision (number of bits of input) and number of outputs. For instance, the quad DAC in an Ornament and Crime is about $12 for the chip alone. The extra circuitry to address such things is not hugely complex, but it’s not really a beginner project.

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#22
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#23

I’m looking to make case for a Norns sheild that will let me play with that Norns in a more stand-alone way. I’m taking some inspiration from the qy-70. Can anyone recommend some nice little buttons for use as a small thumb piano sized keyboard? Velocity and pressure sensitivity would be nice to haves but idk if that’s possible.

Yamaha%20QY70

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#24

I think the easiest way to grab a korg nano key or similiar tiny midi keyboard.
KMI nexus has “pressure” or a ROLI is an mpe device

#25

Does Teensy 4.0 have a built in DAC like 3.6? Very new to this and having a hard time deciphering the information on the website?

#26

No, it doesn’t.

They suggest using either an audio shield (for prototyping), or a similar I2S DAC separately for genuine stereo and higher-quality output.

The reason for this, more specifically, is the microcontroller chip itself that a Teensy 4.0 is running doesn’t have a DAC in it. It’s not that they cut anything from the hardware, it’s that the chip never had one to begin with.

Yes, this makes many of the DIY audio projects that have just used the 14-bit DAC on a 3.2 no longer immediately compatible with a bare 4.0.

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#27

Thank you very much!

#28

I’ve been prototyping some USB selectable switches/power splitters so I can run my tt keyboard and grids into one unit, and select what modules they go. So 2 usb in, and up to 4 usb out. Kinda like a mega switch.

I was able to get things running pretty easily with a bulky analog solution. I have a DP4T rotary switch that sends the D+ and D- signals out to their selected usb out, and an 2PDT toggle to select between the grid or keyboard usb in and the power being supplied externally via USB.

But the aesthetic definitely doesn’t fit in with the rest of my equipment and a slimmer, digital alternative would be a fun project for me, and likely look better (to my eye). I started to tinker around with some leftover Arduino Nano’s and hobbled together enough to read the analog input from a 10k pot, but there is a ton of jitter. Nothing a little extra code couldn’t help smooth out. But now I’m wondering whats the best way to proceed with this?? I’m definitely out of my element here, but this is what I’m considering moving forward and a few questions I have about design choices.

Goal: two channel selectable input, 4 channel selectable output for usb D- and D+ lines.

  1. Should I be using a potentiometer, or is an encoder better suited for controlling an Arduino/Teensy?
  2. My plan was to use a 4052 dual 4-channel multiplexer to route the D- and D+ signals. The logic table being controlled by either a potentiometer or an encoder.
  3. After tinkering a little tonight with the Arduino, I was able to get the analog pin values fairly smoothed out, but do worry about the possibility of unwanted changes driving the logic table output. The analog pin would read values mapped between 0 and 3, and I could sometimes find the spots where a jump from one value to another would happen unintentionally.

All advice welcome!