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Thread: Beginner Trying to make analog/digital hybrid synth with a Teensy 4.0

  1. #1

    Beginner Trying to make analog/digital hybrid synth with a Teensy 4.0

    I had posted this in another person's thread but thought that was the wrong move so here I go. I am a beginner that is new to Teensy and microcontrolers in general and I feel I might have made a mistake getting the Teensy 4.0 immediately because I am lost in the mix. I thought the chip would have a DAC which I also just learned about anyway. I joined the forum and bought the teensy 4.0 because I wanted to make an analog/Digital hybrid synthesizer. So please I have a couple of questions on the digital side because I have figured some of the analog systems so far.
    My questions are:

    First, what true analog DAC would you recommend is best to use with a Teensy 4.0 and an analog synth circuit

    Second, please I am trying to have control of the analog synth through the teensy, however, I still do not fully understand the whole keyboard scanning system and midi to CV conversion business yet. I don't intend to use a "True scanned keyboard" I will just opt to use a midi keyboard such as the Arturia. So my question is if I am to design a circuit and I want to connect the Arturia from its USB to the analog circuit as a CV source for the modules, do I use the Teensy to build the control system or do I have to design a din pin for the analog circuit. Thank you and sorry for the long winded question, I just feel overwhelmed and defeated for choosing the 4.0 and not checking the earlioer versions first.

  2. #2
    You should probably clarify what you mean by “analog/digital hybrid synth”.

  3. #3
    Quote Originally Posted by tele_player View Post
    You should probably clarify what you mean by “analog/digital hybrid synth”.
    Thank you for your reply and advice, Im new to the posting system.

    I am making an analog synth that can have its own indpendent signal path. Also, a seperate wavetable or digital digital synth is intended to be implemented on a teensy. I am trying to use a midid controller to control the analog synth. However I dont know how to set up the connections for midi to cv using the teensy. since the cv has to be 1V/oct and additional gate and trigger signals are required, I am lost in that regards. Thank you

  4. #4
    I googled ‘teensy MIDI to CV’ and found much information on this topic, including one which uses a Teensy 2 to produce 3 channels of note,velocity and gate/trigger, from USB. If you need DIN midi, that easily done, and Google can easily find schematics.
    Last edited by tele_player; 11-16-2019 at 11:21 PM.

  5. #5
    Quote Originally Posted by tele_player View Post
    I googled ‘teensy MIDI to CV’ and found much information on this topic, including one which uses a Teensy 2 to produce 3 channels of note,velocity and gate/trigger, from USB. If you need DIN midi, that easily done, and Google can easily find schematics.
    Thank you once again, The results on google were indeed present. However, since I am new, I bought the teensy 4.0 on impulse after reading some reviews, only to find out it has no DAC outputs which are required to control the analog signals through cv. I already spent $40 on two teensies and didnt want to spend extra, so I decided to ask maybe I was looking at the solutiopn wrong or indedd I do need to perform this task differerntly compared to the previous revisions of the Teensy. Thank you

  6. #6
    Teensy 3.6 is more appropriate. USB host, 2 DAC, but it gets a bit involved if you need more than about 3.3 octaves.

    Maybe you could sell what you bought?

    You described this as a hybrid, but all you really want is a USB MIDI to CV converter?

  7. #7
    Thank you again as you even added mention of a function I didn't know the teensy had, which is the USB host functionality, I was going to use an external USB hub initially. Also, in case my messages seemed obscure, I intend to use one of the teensy as a controller and effects processor for the analog circuit, while the other for digital audio synthesis which I still have to learn. I thought it could be a midi to cv converter only because it was stated online.

    sorry for the continuous questions, but my new question would be can the Teensy 4.0 be used as a USB host like the 3.6.

    Also, In case I don't sell the 4.0, how do I resolve the DAC situation. I just spent the last three hours reading through the forum and saw Paul had commented on another post that an external DAC could be used with the Teensy. I was going to google as usual being new to the digital world, but I thought it wise to ask here first because I could possibly become overwhelmed with the information provided by Google on how to use an external DAC with a microcontroller. Thank you so much for all your help again

  8. #8
    USB Host firmware for Teensy 4 isn’t ready yet, and involves making connections to pads on the bottom of the board. USB Device isn’t ready, either. Currently, the only way to do MIDI on teensy 4 is serial with DIN plugs.

    Frankly, I think you’re going about this all wrong, and should do some simpler stuff to learn what’s involved.

  9. #9
    Senior Member vjmuzik's Avatar
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    USB Host firmware is already fully working on the Teensy 4, the only hard part is that all the hardware for it isn’t already builtin to it like on the Teensy 3.6. There are several breakout boards being worked on in the forum that add the necessary hardware to use it correctly though. If you aren’t worried about breaking anything you can still use it without the extra hardware if you are careful or use a powered USB hub, but USB MIDI devices can be connected to it and used at this point in time only the USB Device firmware isn’t complete yet

  10. #10
    Ahh, thanks for the correction, I misremembered.

  11. #11
    Quote Originally Posted by vjmuzik View Post
    USB Host firmware is already fully working on the Teensy 4, the only hard part is that all the hardware for it isn’t already builtin to it like on the Teensy 3.6. There are several breakout boards being worked on in the forum that add the necessary hardware to use it correctly though. If you aren’t worried about breaking anything you can still use it without the extra hardware if you are careful or use a powered USB hub, but USB MIDI devices can be connected to it and used at this point in time only the USB Device firmware isn’t complete yet
    Thank you both for your replies. I guess I really did try to bite on more than I could chew. I honestly should have researched more about MCU before buying the 4.0 on a based on the Hackaday review. When you say the firmware isnt ready as a usb device, do you mean a computer cant recognie it as a usb device. Also just to clarify, as a usb host, it mean it can take in multiple usb devices as an input source for a computer right?

  12. #12
    Don’t be disheartened, just take it one piece at a time.

  13. #13
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by Orhema View Post
    Thank you both for your replies. I guess I really did try to bite on more than I could chew. I honestly should have researched more about MCU before buying the 4.0 on a based on the Hackaday review. When you say the firmware isnt ready as a usb device, do you mean a computer cant recognie it as a usb device. Also just to clarify, as a usb host, it mean it can take in multiple usb devices as an input source for a computer right?
    Current TeensyDuino V 1.48 has Great USB Serial support as a device. It is already over running at 10 times the output rate and can overwhelm the PC host since it went from 12 to 480 Mbps USB speed. Paul had to spend some quality time to make sure the IDE presented a usable Serial Monitor interface at these increased speeds.

    The "USB Device firmware" is what Paul will be working towards finalizing 11/25 and beyond, and has already advanced the USB Device Serial USB code and some other interfaces to some degree toward that end.

  14. #14
    Thank you for the clarification Defragster. I eventually did spend the night lurking in the forums and decide my safest best was to get a teensy 3.6, then use that as a USB host/hub for the 2 teensy 4.0 I purchased earlier along with a single board computer for giu and app stuff and midi controller. Now I just have to research how to use the 3.6 as a host/hub. Also, I stuck with doing just audio synthesis on the 4.0s, then using the 3.6 as a midi to cv converter for the other 2 teensy and the external midi controller. Please I would like to know if it would be faster to use the 3.6 as midi over serial or midi

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