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Schrabikus

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Posts posted by Schrabikus

  1. SwinSID - a pin compatible alternative to the SID chip

    in MIDIbox SID

    Posted · Edited by Schrabikus

    igi wrote me about oscillator tuning bug, so i've checked and confirming: by default oscillators finepitch is 12 units lower (not cents, 12/127 semitone?) so you need to set finetune to +12 for every oscillator to be in tune.

    We need your help again, Swinkels! :logik:

    Is it clock/oscillator or firmware related?

    Crisp,(and other Swinsid users) do you have the same bug?

  3. SwinSID - a pin compatible alternative to the SID chip

    in MIDIbox SID

    Posted · Edited by Schrabikus

    I've made atmega8515 based SwinSidX2 but it sounds very strange. Only few default patches working ok. Most of them produces noise. I've found that when filter is enabled it distorts sound. Also if patch has non zero attack/release value - they distorted too. Swinsid extensions enabled in config. Is it normal for swinsid or there's something wrong? (same results with another TDA1543, and on lower oscillator frequencies)

    Recorded some samples of it sound, they showing attack/release and filter distortions.

    TK, which firmware youre using with 8515? (i tried both midibox and latest version from Swinkels site)

    swinsid_bug.mp3

  6. SwinSID - a pin compatible alternative to the SID chip

    in MIDIbox SID

    Posted · Edited by Schrabikus

    Couple of questions to Swinkles:

    1. Can i substitute Mega88PA with 168? Which of AVR's in DIP package are good for such overclocking?

    2. Will it work on lower frequencies? (just for testing purposes, i need to figure out where is proplem - MCU/Oscillator/Communication with core, and not shure that my ATmega168 supports 32 mhz. Will it run with 14.318 oscillator? And i have no scope)

    At this moment I have constant high-pitched tone during startup, which sometimes dissapears after CS is loaded and sometimes not. Without core and SR's it starts when i'm touching reset pin of Atmega.

    That's how it looks

    gallery_9659_127_84833.png

    board prototype:

    med_gallery_9659_127_58272.jpg

    Another question is addresed to Thorsten: You said about

    Possibility to control two MBHP_SID (stuffed with original SID chips) and one Stereo-SwinSID module in parallel from a single MBHP_CORE

    Is it possible with Stereo-MicroSwinSID? If so - please give me a hint ;)

  8. SwinSID - a pin compatible alternative to the SID chip

    in MIDIbox SID

    Posted · Edited by Schrabikus

    Tired of SID hunting and wondered by SwinSID samples I've decided to route dual MicroSwinSID board.

    gallery_9659_127_46866.png

    Layout inspired by nILS 8515 module.

    I'm just take NanoSwinSID schematic and combined it with sammichSID. Am I moving the right way?

    I've replaced hard-to-find crystal oscillator with 74LS04+Resonator circuit which was successfully tested with OPL3 chipset. It cheaper and using available components. Also there's pin header compatible with pin-to-pin cable, like in nILS one.

    PCB is not yet tested - i need one more atmega chip + core board. But if there's volunteers i'll share it.

  9. AOUT_LC calibration MBSEQ4

    in Testing/Troubleshooting

    Posted · Edited by Schrabikus

    This is my fourth or fifth unsucsessful attempt for last half-year to calibrate AOUT_LC module.

    Yesterday i've replaced R49/51 with 100k ones and get perfect calibration for 1V, 2V and 4V values. But i have 11,22 instead of 8V. Or 0/11,22/11,22 with Min/Mid/Max

    Replaced opamps, shift registers, checked all resistors and here what i have.

    gallery_9659_127_2543.png

    (1 - Vdd 4,95v)

    I was confused by one point - why there's non linear value of 4,32v at 8V calibration setting. Is it R-2R related? I measured resistance between shift register outs and opamp inputs. Is it looks acceptably?

    Shift register? I replaced it three times with different suppliers ones.

    Or maybe it's software related?

    I'm totally confused and need your help.

    PS. Bipolar supply values is +11,87/-11,97

  21. MBFM and MBSEQ V4 coupling problem [solved]

    in MIDIbox FM

    Posted · Edited by Schrabikus

    Hehe, sometimes problems have to be formulated in writing. Yes, it's low voltage related. I've look to schematics of Midipal (3.3 v midiout too) and removed/replaced 220 ohm resistors at all outs like schematic.

    gallery_9659_127_3197.png

    Now all works fine, but with a little bug (or feature?) - opened and closed HH can't play simultaneously. Is it OPL3 restrictions or smth wrong with my MBFM?

    for example in this case OH somtimes triggered, sometimes not. It's random alike thing.

    OH ....*.......*...

    CH *...*...*...*...

    But when there's no overlapping between them - they played correctly.

    OH ....*.......*...

    CH *.......*.......

  23. MBFM and MBSEQ V4 coupling problem [solved]

    in MIDIbox FM

    Posted · Edited by Schrabikus

    I can't exactly figure out where to post this, so let it be here.

    I have a very strange bug:

    When i connect my LPC17 MBSEQ to MBFM it seemed like there's no midi data received by MBFM.

    BUT! When i connect it via midi thru enabled device (like Midipal or Shruthi) - all ok. When i connect midi keyboard directly to MBFM - all fine. And connection to midi port of PC also gives me good result.

    The MBSEQ works fine, being directly connected with Shruti, Midipal and PC.

    When i connect midi cable (with other end in the air) to MIDI OUT of MBFM - some midi data appears, but with a lot of dropped out notes.

    Non working config:

    [MBSEQ]--->[MBFM]

    Working config:

    [Keyboard]--->[MBFM]

    [MBSEQ]--->[MIDIPAL]--->[MBFM]

    [MBSEQ]--->[MIDIPAL]--->[sHRUTHI]---->[MBFM]

    [MBSEQ]--->[sHRUTHI]--->[MBFM]

    [PC]--->[MBFM]

    Half working config:

    [MBSEQ]--->[MBFM]---->

    Scratching my head.... :unsure:

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