Forum Rule: Always post complete source code & details to reproduce any issue!

Search:

Type: Posts; User: tomas

Page 1 of 2 1 2

Search: Search took 0.00 seconds.

  1. Replies
    191
    Views
    5,958

    CMSIS provides ready-to-use implementation. For...

    CMSIS provides ready-to-use implementation.
    For interpolation you need call arm_fir_interpolate_init_f32 (once) and arm_fir_interpolate_f32 ( in the loop)
    For decimation you need call...
  2. Replies
    191
    Views
    5,958

    If you did oversampling "by the book" you would...

    If you did oversampling "by the book" you would need polyphase FIR interpolator at the input and polyphase FIR decimator filter at the output. These are costly. Not doing things by the book results...
  3. Replies
    191
    Views
    5,958

    With max resonance you can clearly hear that...

    With max resonance you can clearly hear that analog filter has some "gritty" quality to it (2:52 of your video), while digital is sterile and lacks this effect completely.
  4. Replies
    191
    Views
    5,958

    I noticed that you are using copy of the same...

    I noticed that you are using copy of the same input sample when oversampling and averaging output. You may consider using linear interpolation on input and dropping on output.
  5. Replies
    191
    Views
    5,958

    Sorry, I did not want to sound harsh, I realised...

    Sorry, I did not want to sound harsh, I realised that I was too quick to post feedback, so I deleted it as it requires more time. I will run newest code and do more tests.

    UPDATE: Now I am running...
  6. Replies
    191
    Views
    5,958

    For obvious (performance) reasons nobody uses...

    For obvious (performance) reasons nobody uses math library tanhf for audio. It is way too slow. And if you read previous posts, you would see that I earlier wrote to use float everywhere, not double...
  7. Replies
    191
    Views
    5,958

    For what it is worth soft saturation (distortion)...

    For what it is worth soft saturation (distortion) is absolutely essential to Moog sound. https://www.youtube.com/watch?v=5sAq0FjRUI4
    And using tanh() in simultation is not random choice. Moog ladder...
  8. Replies
    191
    Views
    5,958

    Was busy with other stuff, but over the weekend I...

    Was busy with other stuff, but over the weekend I intend to pull that code and check against analog 4pole "moog" filter simulation in hardware Virus TI synthesiser. Guys from Kemper Music are famous...
  9. Replies
    24
    Views
    710

    Here you can find the document that describes...

    Here you can find the document that describes from where the delays come from:
    https://www.ti.com/lit/wp/slyy095a/slyy095a.pdf?ts=1613141458124
  10. Replies
    191
    Views
    5,958

    For what it is worth it is not possible to...

    For what it is worth it is not possible to exactly simulate non-linear analog filter with feedback in digital domain because of the delay introduced by digitization.
    So called "zero delay" filters...
  11. Replies
    125
    Views
    10,439

    Sorry. Apparently I need to get my eyes checked.

    Sorry. Apparently I need to get my eyes checked.
  12. Replies
    125
    Views
    10,439

    For better reliability of your MIDI IN consider...

    For better reliability of your MIDI IN consider 10k resistor between pin 7 and ground of optocoupler as explained here:...
  13. Replies
    191
    Views
    5,958

    As I wrote in my earlier post, I advise to keep...

    As I wrote in my earlier post, I advise to keep attention to those little details such as using floating point constants:
    4.0 is a DOUBLE (64-bit) constant. It causes your computations to be done in...
  14. Replies
    191
    Views
    5,958

    Two performance suggestions: 1. Use f for...

    Two performance suggestions:
    1. Use f for constants: like 0.9892f instead of 0.9892. Constants by default are double. Float is twice as fast even on hardware FPU
    2. Use float instead of double...
  15. Replies
    35
    Views
    1,151

    SNR is measured in dB. And it was observation /...

    SNR is measured in dB. And it was observation / comment / remark (hence "approx" word), not measurement. PT8211 is so bad, not only with regards to noise but mainly to distortion that I wonder why...
  16. Replies
    166
    Views
    9,328

    "Brand" effect. Everything that has name...

    "Brand" effect. Everything that has name "Raspberry Pi" on it gets media coverage. Every web site talks circles about it and praises it as it was the best thing since sliced bread. They don't mention...
  17. Replies
    166
    Views
    9,328

    The other person could say: Focus on your core...

    The other person could say: Focus on your core product/business. High-performance microcontrollers in tiny user-friendly package. Why would anyone bother to think about yet another 12-year old Cortex...
  18. Replies
    166
    Views
    9,328

    Cortex M0 was introduced in 2009. So it is 12...

    Cortex M0 was introduced in 2009. So it is 12 year old tech.
    CPU in Raspberry PI 1 wasn't 12 years old.


    But typical user does not program (majority of) them using APIs (yet), of course except...
  19. Replies
    166
    Views
    9,328

    +1. That is my sentiment too. I have seen such...

    +1.
    That is my sentiment too. I have seen such hype so many times in the past. Don't waste time on platform that is not bringing anything new.
    M0 is old tech, underpowered, lacking crucial...
  20. Replies
    166
    Views
    9,328

    Yes, I have been running it at 750MHz super...

    Yes, I have been running it at 750MHz super stable, but decreased longevity https://www.nxp.com/docs/en/nxp/application-notes/AN12253.pdf worries me a bit.
  21. Replies
    166
    Views
    9,328

    And it is 5 times as useful :-) Seriously. I am...

    And it is 5 times as useful :-) Seriously. I am making project that requires LOT of horse power and will probably use 5 or more Teensy 4s. And I need bare metal,
    so Linux based things like Raspberry...
  22. Replies
    166
    Views
    9,328

    +1. and 600MHz T4 is even better :D There is...

    +1. and 600MHz T4 is even better :D


    There is detailed chart on page 180 of reference manual for F401.
    FIFO has four 32-bit words that can act as 16 bytes or 8 half-words (16-bit).
  23. Replies
    166
    Views
    9,328

    It does. Page 166 and page 180 of STM32F401...

    It does. Page 166 and page 180 of STM32F401 Reference manual: "Four-word depth 32 first-in, first-out memory buffers (FIFOs) per stream."
    FIFO in STM32F401 is universal that handles not only I2S...
  24. Replies
    35
    Views
    1,151

    Exactly, noise floor approx -58dB that is less...

    Exactly, noise floor approx -58dB that is less than 10 bits. Good cassette decks in '80s were able to get >70dB.
  25. Replies
    166
    Views
    9,328

    I2S without masterclock limits the number of DACs...

    I2S without masterclock limits the number of DACs you can connect to those that don't need MCLK. Also since this PIO seems to be implementing I2S in software
    the question arises about clock jitter...
  26. Replies
    35
    Views
    1,151

    Now do the same with PT8211 and you will see how...

    Now do the same with PT8211 and you will see how bad it really is. I would say it is no better than '80s compact cassette.
  27. Replies
    166
    Views
    9,328

    I also hate Arduino IDE, but there is a solution...

    I also hate Arduino IDE, but there is a solution already. I strongly recommend taking a look at PlatformIO (Visual Studio Code addon). It is night and day compared to Arduino. I used various IDEs for...
  28. Replies
    35
    Views
    1,151

    I am using studio grade ADC AK5394A (123dB SNR/...

    I am using studio grade ADC AK5394A (123dB SNR/ 123dB DR) with Visual Analyser. With regards to your results, your power supply may be the culprit too. Disconnect USB and try running from some high...
  29. Replies
    35
    Views
    1,151

    I would actually say that pretty much ALL current...

    I would actually say that pretty much ALL current high quality sigma-delta audio DACs have oversampling built-in with multistage decimator and FIR filters that have quality way above what is offered...
  30. Replies
    317
    Views
    39,326

    Yes it would be very handy to have SDRAM option...

    Yes it would be very handy to have SDRAM option on board. Note that this Daisy board uses STM32H750 microcontroller at @480MHz so it is already significantly slower than existing Teensy 4 @600MHz,...
  31. Replies
    4
    Views
    324

    First, in almost all practical cases you use...

    First, in almost all practical cases you use windowed sinc.
    Second, as I wrote, its better to do range reduction yourself.
  32. Replies
    4
    Views
    324

    Range reduction of large arguments in...

    Range reduction of large arguments in trigonometric functions is always problematic because PI constant used is inherently inaccurate. There is infamous bug in Intel x87 FPU hardware that causes sin...
  33. Replies
    22
    Views
    757

    Yes see:...

    Yes see:
    https://www.mathworks.com/help/dsp/ug/optimized-fixed-point-fir-filters.html
  34. Replies
    22
    Views
    757

    It works because you have converted (rescaled)...

    It works because you have converted (rescaled) floating point coefficients to fixed point. If you use short data type (16 bit), coefficients are supposed to be in the range of -32768 upto 32767 and...
  35. Replies
    22
    Views
    757

    Datatype short is 16 bit - it is too low...

    Datatype short is 16 bit - it is too low resolution for coefficients of a good filter. Also if you just change the data type from int to short, you will likely overflow the range, as short has only...
  36. Thread: Led strip

    by tomas
    Replies
    2
    Views
    216

    I did that already in the past. True power issues...

    I did that already in the past. True power issues are a problem if you want to light up entire strip, but to light up only a few leds out of say 4 octave keyboard (48 leds) (usually you don't have...
  37. Replies
    37
    Views
    10,673

    Just my 2 cents worth: I also faced problem that...

    Just my 2 cents worth: I also faced problem that I needed a decent and FAST debugger for complex programs written for embedded systems (not only Teensy but STM32 too). Although I got debugger with...
  38. Replies
    3
    Views
    329

    Soldering Teensy is not rocket science. Certainly...

    Soldering Teensy is not rocket science. Certainly not more complicated than soldering Arduino Nano or Micro. Keep temperature in check, don't use too much tin and heat the pad and the pin not more...
  39. Replies
    26
    Views
    4,141

    I got Access Virus TI hardware synth (virtual...

    I got Access Virus TI hardware synth (virtual analog) and you can pretty easily get bass/tom/snare drums with it with self-oscillating 4 pole resonant filter that has its cutoff frequency modulated...
  40. Replies
    317
    Views
    39,326

    Defragster - thank you very much.

    Defragster - thank you very much.
  41. Replies
    317
    Views
    39,326

    I also would like to know if part number to be...

    I also would like to know if part number to be used in future teensy will be i.MX RT1176 and what is planned release date of 1GHz Teensy, please?

    Happy festive season to everyone!
  42. Replies
    13
    Views
    1,079

    With all due respect, "Teensymoog" is sonically...

    With all due respect, "Teensymoog" is sonically nowhere near real Minimoog. The same applies to pretty much any synth created using Audio library for a number of reasons:
    1. Aliasing - audio library...
  43. Replies
    23
    Views
    2,963

    OK, I see what you meant. The thread is flat, no...

    OK, I see what you meant. The thread is flat, no threads are shown by default, as you noticed. A clickable "1 reply" button reveals direct replies, just making easier to locate them. You don't need...
  44. Replies
    23
    Views
    2,963

    All Discourse setups I have seen work with flat...

    All Discourse setups I have seen work with flat threads. So frankly, I don't know what you saw.
  45. Replies
    23
    Views
    2,963

    @luni - thank you for the feedback, yes pasting...

    @luni - thank you for the feedback, yes pasting images straight into post is huge time saver.
  46. Replies
    23
    Views
    2,963

    There is an import script/procedure and tutorial:...

    There is an import script/procedure and tutorial: https://meta.discourse.org/t/importing-from-vbulletin-4/54881
    But I did not do VB import myself, so I can't comment about how good or bad the...
  47. Replies
    23
    Views
    2,963

    For what it is worth, may I suggest Discourse...

    For what it is worth, may I suggest Discourse https://www.discourse.org/ It is modern community software, authored by people behind StackOverflow, in many ways better than vBulletin and classic BB....
  48. Replies
    21
    Views
    1,753

    I also think that Wolfson codecs are generally...

    I also think that Wolfson codecs are generally very good. I got bunch of WM8591 (110dB DAC/102db ADC) and that is true that it requires proper mixed signal design of your board but results are very...
  49. Replies
    21
    Views
    1,753

    For what it is worth, Amiga Paula chip had 4...

    For what it is worth, Amiga Paula chip had 4 separate 8 bit multiplying DACs each with independently controlled sampling rate and with 6 bit digital volume control for each DAC all driven by...
  50. For what it is worth, as per my own testing,...

    For what it is worth, as per my own testing, Teensy 4 is fast enough to produce over 400 band-limited (anti-aliased) PolyBLEP square and/or sawtooth waves @44.1kHz (custom code, not using Audio...
Results 1 to 50 of 53
Page 1 of 2 1 2