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Thread: [posted] (yet another) MIDI to CV Converter!

  1. #26
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    Quote Originally Posted by Orhema View Post
    Thank you so much for your work and providing it to others especially beginners like me. I want to knOW If I can use the Teensy 4.0 in this project
    I am glad this project looks useful to you. I used the Teensy 2.0 in this project because I wanted the 5V outputs on the gate and trigger, and the 2.0 is more than enough to get the job done. Of course you could use a 3.3V board like the 4.0 if you wished, but my recommendation would be to stick with the 2.0 since the extra horsepower of a 32-bit board is not needed for this project. Also, if you are using my PCB design, the pinout is for the 2.0 and would not be compatible with the 4.0. Otherwise you would need to breadboard the circuit.

    If you're interested (and in the US), I could send out one of my PCBs to you at cost. I have a few extras lying around. You would need to source the components from Digikey or Mouser.

  2. #27
    Thank you for your advice. Will there be a way to convert the 3.3v out to 5v

  3. #28
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    Quote Originally Posted by Orhema View Post
    Thank you for your advice. Will there be a way to convert the 3.3v out to 5v
    There are a number of different ways to convert 3.3v logic to 5v. The first question to ask is whether you even need to convert. This depends on the synthesizer you intend to drive. It is possible that 3.3v logic will be sufficient. For example, even if the input is 5v TTL logic, it will register high at 2v so can be driven by a 3.3v output. Alternatively, your synthesizer may require 12v logic. Some do.

    I suggest you take a look at this link for more info on logic conversion.

  4. #29
    Thank you that makes sense. I know some synthesizers are +/-5V and others are +/-10V. I am guessing since mine is a +/-5V It would require a 5V level conversion

  5. #30
    Please what pins on the 2.0 did you use for the gates. Also can the gate be used to control external ADSRs

  6. #31
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    Hi elkayem,
    Is there a way to add portamento/glide to the midi cv interface? I think it is a very important function.
    The Portamento amount could be controlled with the rotary encoder.

  7. #32
    Senior Member oddson's Avatar
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    Analog portamento is typically a lowpass filter (with a very low cutoff) or slew limiter to retard the voltage shift on note changes.

    It can be done fairly easly in either digital or analog domains.

  8. #33
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    Nice project, do you think it would be possible to expand it to 6 note polyphonic, I have a teensy 3.5 available for the extra pins etc.

    I don't need the pitchbend as that is handled elsewhere, but Pitch, velocity and gate for 6 notes would be awesome, looking at the code it seems fairly easy to expand it but maybe the 2.0 would not cope with 6 notes.

    Also I would like to use MIDI (5 pin) and not USB MIDI for the input, again I think this is possible with additional circuitry for the MIDI in and code changes.

  9. #34
    Senior Member oddson's Avatar
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    I'm nearly certain the T2.0 would handle three more outs.

    The challenge in extending this application isn't only from the coding but also from the analog circuit.

    This is fairly advanced stuff so are you capable on both sides?
    Last edited by oddson; 03-07-2020 at 04:26 PM.

  10. #35
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    Thanks for the reply, much appreciated.

    I can probably build it ok, analogue and digital circuits are not a problem for me, I've been in IT for over 40 years mainly in hardware. I would say add three more DACs to the circuit and the MIDI in with onto Isolator.

    Coding is another matter, its not my strong point, but I have built and coded a 64 way analogue/digital MUX for reading pots and switches into my programmer project. Got it reading stuff, so I'm familiar with some parts of the coding.

    I see you are using MCP4822 DACs, I have 10 of them on order and most of the rest of the parts in my spares bin so it should not be too hard to build a board very quickly with the hardware an have a go at modifying the code.
    Last edited by craigyb; 03-07-2020 at 05:10 PM. Reason: more information

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