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  1. K

    Loop to slow for MIDI library read() method

    Keep MIDI.read() in your loop and work more on optimising your OLED code. That's where the problem is. If updating a portion of the screen only instead of a clear and full update makes no difference, you must be overlooking something. Also, does it really matter if you are slow reading a clock...
  2. K

    ADSR with latching attack?

    You're thinking of the "unconditional contour" option on the MemoryMoog. It's not common, but an interesting option nevertheless - kicking off a cycle from a trigger rather than following a gate.
  3. K

    Microdexed on Teensy 4.1 - no usb audio

    The help for the USB output object says this: "USB input & output does not cause the Teensy Audio Library to update. At least one non-USB input or output object must be present for the entire library to update properly." I haven't looked at the code, but quite possibly that's what you're...
  4. K

    Filter Modulation

    I have a very simple example here LFO Modulation that might help. It has an LFO modulating both an oscillator and a filter with an independent amount control as well. It doesn't use an envelope, but inserting one follows exactly the same pattern.
  5. K

    Fun with FM synthesis

    And now version 2.
  6. K

    Using Teensy for big MIDI control surface

    I don't understand why you would think I do - I explicitly stated that interrupts are better and more elegant. But from your comments it seems like you are new to this, so I tried to address some aspects that are relevant and understanding them should help you make a better solution. But...
  7. K

    Using Teensy for big MIDI control surface

    Some thoughts: - memory is a non-issue for this application - interrupts are more efficient and more elegant to implement than polling (what you are calling the digital pin method, but both methods are digital) - if you are seeing such a big difference though, check your code. I reckon a...
  8. K

    Using Teensy for big MIDI control surface

    You can daisy chain 8 MCP23017s off one i2c bus, giving 128 (interrupt capable) digital pins. That would support 64 encoders (if you're not using switches). And the Teensy 4 has 3 I2C busses, so you can support 192 encoders without having to do anything crazy. You will also have plenty of...
  9. K

    5 pin MIDI in not working

    Your circuit is fine and won't damage the Teensy. it's very easy to get pins 4 & 5 mixed up on the DIN - that's what I'd check closely. Specifically - make sure you are viewing the connector from the intended direction. You might consider adding a resistor and LED off pin 6 (connected to VCC)...
  10. K

    Fun with FM synthesis

    I put together a Eurorack 4-operator FM voice using parts of the Dexed audio library object. Because I wasn't trying to recreate a DX7, I dropped various things (like the LFO, pitch envelope, detune, effects), changed others (coarse frequency down to 1/128 like the OpSix, ADSR envelopes...
  11. K

    Fun with FM synthesis

    I have just returned to this and your code looks very promising, so I had a go with the Audio Library object version. I am using a Teensy 4.1 and the problems I describe occur with both the audio shield and I2S into a PCM5102A. I have also built with the CPU speed changing from 600MHz to...
  12. K

    Building and learning synthesis with Teensy - a resource I've made

    Thanks for spotting that - fixed. :-)
  13. K

    what to do with SAMPLE and HOLD

    Sample and hold on an input noise signal is great for a rhythmic random cut-off changing, or for "robotic" sound effect pitch jumps. This app let's you play around with both: http://thewessens.net/synthbook/#sample-and-hold Lower the cutoff and increase the filter amount, and/or increase the...
  14. K

    T3.2 power up issues

    I tried a few places - setup() was too late. Even startup_late_hook() was too late.
  15. K

    T3.2 power up issues

    No one has any suggestions for how this might be manageable via software on powerup? My thinking now is a supervisor chip like a MIC803 connected to the reset pad is the best option - just a bit of a nuisance connection on the T3.2 Edit: Looks like putting a short delay (an empty loop) in...
  16. K

    T3.2 power up issues

    Hi, I think I've got a situation where the external power into my Teensy 3.2 is marginal at startup. Let me explain the context and I'd be glad to hear any suggestions for things I can do in code to make it more tolerant, or if the issue may arise from something else? I made a little Eurorack...
  17. K

    Eurorack drum machine to show - and a question about Teensy 3.2 DAC

    Must have been just working too late. :-) It's all good now - and proving a lot of fun. I must say I'm very happy with my first use of the T3.2. Small, fast, and with a DAC! Glad to be able to avoid the audio shield for this little project.
  18. K

    Eurorack drum machine to show - and a question about Teensy 3.2 DAC

    Thanks for that. I did try the dc option with some success. I didn't think of using a queue, so I'll try that too. There seemed to be some glide in the steps so maybe the queue option will be cleaner. I'm also a bit confused by the levels. I know what voltage I need to appear on the DAC to get...
  19. K

    Eurorack drum machine to show - and a question about Teensy 3.2 DAC

    Hi, I had some spare space in my Eurorack and decided to make a little drum machine to fill it. I used a Teensy 3.2 with samples and a LED matrix as the primary control for connecting beats to samples. In "bar" mode they are beats in the bar, but in "poly" mode they are "every nth beat" -...
  20. K

    Beatstep MIDI communication with teensy 4.0

    Organise and optimise your code, and never use delay (except possibly in setup code). That will make it much easier to work with. For example, lot's of places arrays could be used to avoid the huge switch statements, and you could reduce your usbmidi code down to: if...
  21. K

    Start and Stop Sinewave sound

    Look a bit more at the envelope object. You can set the timings for the stages. If sustain is set 0, then you don't even need to worry about the precise time of calling noteoff(), but you could use attack(0), hold(19), decay(1) say to get a 20ms tone that doesn't end with a pop. Then just call...
  22. K

    Help with Sawtooth LFO Indicator

    Use the DC offset function.
  23. K

    Building and learning synthesis with Teensy - a resource I've made

    I definitely hope it helps people get started - and helps them understand things within a broader context. Much of what I wrote I already knew, but there were still a good few places where I realised I had gaps in my understanding, and others where my "understanding" was just plain wrong! :D
  24. K

    Building and learning synthesis with Teensy - a resource I've made

    I've always been into teaching and have written a lot of things for learning maths, so given the fun I've had (re)learning synthesis, coding with web audio and building synthesiser tools with Teensy, and also the number of people who want to use the Teensy to do similar things, I thought it...
  25. K

    Roadmap "Dynamic Updates": any effort going on?

    I haven't run into any difficulties dynamically creating and patching audio objects, but I just do it once at startup - I don't change the connections arbitrarily during the lifetime of the program. (Is there something in the library that would make that a problem?) My use-case is I have 32...
  26. K

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

    If you mean you want to learn about the electronics of the analog synth, and build things with a Teensy to interface with it, I'd recommend the Moog Werkstatt. If you want a straightforward monophonic analog synth with all of the key bits, but no more, and want to experiment and learn, I'd...
  27. K

    Fun with FM synthesis

    This looks very cool. Thanks for posting. I've been looking at the Korg Opsix - seems they've really thought out the interface well. It's quite difficult to make FM synthesis immediate in the way subtractive synthesis is. Makes me interested to whip something similar up with the Teensy. Ken
  28. K

    Iconic vintage synths with Teensy?

    I'd also like to encourage this. I love the multitimbrality of the Blofeld, but it's hard to do sound design with so few knobs, so I used a Teensy 4 and a number of port expanders/MUXes to make a control surface for it. And to fill in some of the gaps in the Roland Boutique JP-08 and JU-06 I...
  29. K

    Iconic vintage synths with Teensy?

    What you can emulate is the experience of creating sounds with those synths. It definitely won't sound the same, but the experience can still be worthwhile. For example, I think the website emulating the Juno 106 at https://juno-106.js.org is absolutely fantastic and a great project. And you...
  30. K

    A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library

    I've put together some documentation for this now (having a few "early adopters" have a go at building one certainly puts a bit of pressure on to sort stuff out. :) ) A User Guide describing the theoretical basis for the device, the specifications, and the available controls is here: The...
  31. K

    Teensy 4.0 Audio Project Multiplexer Wiring Help

    Have a look at the SparkFun hookup guide for the 74HC4051 - it's the same thing except only 8 lines (and hence only 3 address pins). https://learn.sparkfun.com/tutorials/multiplexer-breakout-hookup-guide/all In your first circuit you seemed to have EN tied high (and to 5V - don't use 5V with...
  32. K

    A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library

    If you look at the encoder matrix at the top left, there is a select encoder to select a row and then 4 encoders to change values. The upper value in each case is changed by rotation, and the lower value by clicking. Generally the lower values cycle through a few values like wave shape, or...
  33. K

    A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library

    I've progressed from the prototype stage to what I think is a shareable version. Putting together a webpage now with details. It fits nicely in the enclosure I chose, and it's nice to have the connections robust instead of dangling wires. :-) The LCD display is working well and showing some...
  34. K

    A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library

    Just realised there is an error in the triangle calculation in the code I posted earlier. The triangle wave only has the odd harmonics, so need to make a small change as follows: ... case TRIANGLE: if (m % 2 == 0) table[t][n] += ((m >> 1) % 2 ? 1 : -1) * maxAmp /...
  35. K

    A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library

    I've added some extra functionality to my synth - I used the spare memory to add some basic 808 style drum sounds (bass, 3 toms, snare, and open and closed hi-hat). After trying out a few variations, I've ended up with the following approach where they are controlled by presses on the otherwise...
  36. K

    A little FFT demo for 480x320 TFT (HX8357D)

    Thanks for posting this. It's a nice little demo and just what I needed to show someone. Porting to my LCD was trivial and saved me heaps of time. :-)
  37. K

    A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library

    I agree. It would be great to have the aliasing issues actually addressed in the library, but the wavetables are easy and a big improvement. Despite saying above that it wasn't a priority, I extended my code today to handle a bandwidth limited Pulse waveform with support for low frequency...
  38. K

    A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library

    Yeah - the aliasing is a pain. At the moment I generate wavetables for sawtooth, square and triangle waves using a modification of some code from the forum (see below), but I intend to refine things much more. Specifically, the aliasing on the Pulse wave is quite bad, but it can't be solved in...
  39. K

    A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library

    Hello. I thought I'd share a project I've been working on for the last 2 months - A subharmonic synthesiser and polymetric sequencer with Teensy 4 and audio library inspired by Euclidean Rhythms, and the Moog Subharmonicon (and standard subtractive synthesis). Euclidean rhythms use the...
  40. K

    uVGA library with non-default pins

    Got it working. The defines are a bit broken, so it's not just a matter of removing the #if 0, but it's not much more than that. I can't be sure that there aren't any other side-effects, but it seemed ok.
  41. K

    uVGA library with non-default pins

    Well I'll certainly try re-enabling FTM3 this evening when I get home. Fingers crossed it was just commented out for testing... :-)
  42. K

    uVGA library with non-default pins

    That code snippet looks odd - seems to imply FTM3 is disabled? But the README says: "1 FTM with 4 channels (on teensy 3.6, only FTM0 and FTM3 are possible. on teensy 3.2, FTM0 only). All others channels will be free." Has anyone used this library successfully with the non-default setup?
  43. K

    uVGA library with non-default pins

    I believe pin 34 is E25, and from the library info: "The pair (hsync_ftm_num, hsync_ftm_channel_num) defines the pin generating Hsync signal. Look at teensyduino's teensy3/core_pins.h file, CORE_FTM*_CH*_PIN On teensy 3.6, valid pairs (not on port D) are: (0,0) => pin 22 (0,2) => pin 9. This...
  44. K

    uVGA library with non-default pins

    Hi, I am using the uVGA library with a Teensy 3.6, and all worked fine with the default settings. But for port-related reasons, instantiating the uVGA object using (hsync_ftm_num, hsync_ftm_channel_num) = (3,4) as described in the README suits my requirements better, but I can't get it to work...
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