PIC-based fraktal synth

[State Machine]

Very clever use of the OSCTUNE function Yerpa !!! Saw the video and agree, the vibrato + plucked strings are very cool !!! Great work .....

Bill

[oootini]

loaded that new hex last night. pretty fun! is it just me or does the pic synth run a lot quieter since i stuck in the new hex?

[yerpa58]

thrush, it should be as loud as before. However, it is never loud enough for me, and I am burning thru 9 volt batteries way too fast. My next iteration of this board will be slightly smaller to save PCB cost, but I am adding a transformer-coupled line out jack, and a 9 volt power in jack using the popular stompbox power jack format.

I'm also testing a new extension to the plucked string algorithm, I'll post samples as soon as I get something good.

I'm not impressed with the TDA amplifier chip, can anybody recommend a nice loud class-D amp chip that runs on five to nine volts DC?

[State Machine]

[oootini]

i've been asked to help a friend fill a space in a gallery with some sound. i'm thinking of using the pic synth using ldr's instead of the pots to make an interactive piece? like if i had some spot lights on the ldrs and people walked by breaking the light...

[State Machine]

[monokinetic]

As a matter of interest, has anyone tried compiling the PICsynth with one of the 4.x versions of the CCS compiler? I ask because I'm contemplating buying it, partly to work on some additions to the code...

David

[yerpa58]

I compiled with 3.249, only because I know & trust that version. If you buy the newer versions, I think you can then legally download 3.249 from CCS. Should be no problem compiling with the newer versions, though.

There is a lot of room left in the chip for more code. What are you thinking of adding?

[monokinetic]

Hi yerpa,
I planned to mess around with the synchronisation ideas bounced around earlier in the thread. I think I get how the sequencer stuff that catweazle suggested works. I want to try and get a 5v clock going to a PIC pin and use this to step through the sequencer.

In terms of extensions of the synthesis code, I hadn't really thought of that. Yet....

Oh and by the way, I also came across a mention of using the third switch in the source code as a sequencer lock. I hadn't realised there was any algorithm using the third and fourth switches! Any idea how it works?

Have you made any progress on your harmonic pad? I was enjoying your plucked string at the weekend!

Cheers

David

[yerpa58]

Hello monokinetic,

I haven't done any actual code for the harmonic pad, but I figure I can do about six or eight independent wavetable oscillators at once, each with independent envelopes. I'm basing that estimate on the PIC running about 8 MIPS, gives about 200 instructions per sample. I'm guessing that it will sound gritty, since the independent oscillator values will have to be summed, then bit-crushed back down to an eight-bit value. Also, with 8-bit samples it will help to add dither to prevent cancellations when harmonics get locked out-of-phase. So I am imagining a fuzzy, drifty kind of sound.

Still, it might sound cool and I really want to try it. I'll post it here as soon as I have something.

[monokinetic]

Hiya,
fuzzy, gritty, dirty sounds perfect to me

One other random idea I had today was to use the remaining free _PIN_aux2 to enable a record of the pots. Once the switch is set, the movement of the pots could be stored. Then once the switch is released the users movements could be "played back". It's just an idea so far, haven't looked at implementation yet

Oh yes, and in the code there is this:
#define _PIN_aux1 PIN_B1 // Lock/Store sequencer

I've got my LED display working now, so exploring the sequencer function. I can't see a description of how to use this lock/store though. Any ideas?

David

[yerpa58]

monokinetic,

I like the idea of recording the pots. It could work but might slightly reduce the sample rate. The fraktal synth does not run from a sample clock. It just makes samples as fast as it can, all the time. The "birds" routine uses the recording technique you describe, but only on one pot. The second voice is delayed from the first by recording the pot values from the 1st voice into a circular buffer and playing them along later using voice 2. I think the delay can be up to about sixteen seconds.

I don't think pin_aux1 or pin_aux2 are used anywhere in the code. You could use them for anything you want. There are also plenty of catweazle's mysterious programming nuggets that I have not figured out. like what is playtrigger for?

I don't think lock/store is doing anything for the sequencer, either. Here's how I build up a sequence without it:

Use knob 2 to set the speed. The funnest part is using knobs 3 and 4 rocking together to set up a nice little melody. Then let it play while using higher knobs to adjust attack decay, fm parameters, etc. Rinse and repeat

[catweazle]

if playtrigger is true then the selected algorithm is initialised in
function APP_TriggerPlay(void)

here you can clear buffers, fill buffers with predefined values etc

It took a while to understand what I've done there long time ago.

APP_InitAlg(void) would be a more comprehensive name, indeed.

Application.c

[catweazle]

...
you can connect a 10..25Mhz Crystal at the OSC pins
(with 22pf caps to ground on each crystal pin) and comment the internal oscillator setting out and activate the PLL /Crystal setting (config fuses)

delete this line if using a crystal
#define OSCINTERNAL // use internal oscillator (8Mhz,PLL4 -> 32MHz)


With the internal PLL (x4) you can get the PIC running at 25MIPs (100MHz)
that really works (but some internal periphericals like uart etc may not
function properly. But for this configuration it should work.
(maybe some delay and lower sampling rate of adc is needed)

in case of easy building / minimizing parts and costs,
i used the internal osc.

[napierzaza]

I have a few questions, hopefully people are still reading this thread.

What's the most current version of this software?

What is the schematic for this most current version?

What is the minimum I need to breadboard for me to check if it's making a sound?

I ask this because I burned a 18f4620 and setup the VCC,VSS pin 17 and some buttons but it's not really responding. The LED on pin 40 does nothing and I don't get the impression it is functional. At the same time I don't know if it works without wiring the pots or something, which is something I'd rather do after I get the base going.

[monokinetic]

[napierzaza]

That's some great info David.

Yes, I'm a midiboxer. I'm using the Midibox Parallel burner. It's actually pretty good, since I had 2 x 18f4620s from my Midibox (SID) project since they now use 4685s. I might be wrong, I've planned on making a SID,SEQ and FM. Since I only made the SID and FM I might have been actually stealing my SEQs PICS but no matter, That's on the back burner.

Unfortunately I didn't document which file I burnt. But since you're saying 6 is the most recent, I'm going to burn again and use 6.

I'm using a breadboard. I smartly thought to do that before making a etched PCB. I know that it's 5v because I've been measuring it, and I have a LED and a resistor directly on the power rails to make sure it's powering up.

I have a number display package, but unfortunately it is common cathode and not common anode. So I need the pic to supply 5v instead of supplying GND. Is this okay? Or would I have to jury rig some kind of transistor reversal?

[monokinetic]

[napierzaza]

Yeah, I'm going to erase/reflash the pics just to make certain.

I hope I can use the existing display I have, I am an avid part recycler and I have about 6-8 of these which I'd love to put to use.

[napierzaza]

Okay perfect. I got it working. Apparently pkp (linux pic burner) is pretty weird about loading files. Looks like it's working perfectly, except the audio portion is kind of useless. I'm not sure what it's supposed to do, it just destroys the audio.

[okvern]

Fellow Builders,

Some of you might recall The Oscillator from earlier in this thread (he's tall, dark, and noisy). After "performing" with him a few times, I realized that what what he really needed was a rhythm section. I pretty much forgot about this, until I saw the VS1053 breakout board at Sparkfun.

The VS1053 is a fascinating chip: all kinds of sample decoding and a general MIDI synth, all in a tiny, battery-compatible package. At the time I picked up the board, they were selling for $19--only a little more than the chip itself.

The attached video shows an Arduino MIDI sequencer I wrote running three channels of MIDI (drum, bass, and groovy organ) on the VS1053. I still need to add controls (because a simple sequencer is kind of dull) and package it up so that it'll fit in The Oscillator's control box.

Thanks,

Ole

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VS1053.mpg
Description:		Download (listen)
Filename:	VS1053.mpg
Filesize:	3.76 MB
Downloaded:	876 Time(s)

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[yerpa58]

I made a few changes to the sequencer. Now the switch on Port B1 (Pin 34) is a Step/Run function. In the step mode, pot #3 steps thru the sixteen steps. The switch on Port B0 (Pin 33) is now an Edit/Lock function. Note parameters can only be changed when this switch is in the edit position. There are sixteen steps instead of eight. Each step can have a different sound setting. The settings are saved to the PIC's EEPROM whenever the Edit/Lock switch is returned to the Lock position. That way, the sequence you compose will be saved between power cycles.

Changing the vibrato switch makes all of the envelopes max out for a brief period.

I was starting to add a morphing oscillator preset when I got sidetracked on the sequencer. I hope you like it. The morphing oscillators will be next.

Here's a brief sample of the new sequencer.

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fraktal_sequencer.mp3
Description:		Download (listen)
Filename:	fraktal_sequencer.mp3
Filesize:	1.79 MB
Downloaded:	1013 Time(s)

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xsynth2_files.zip
Description:		Download (listen)
Filename:	xsynth2_files.zip
Filesize:	62.84 KB
Downloaded:	528 Time(s)

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[oootini]

that new additon sounds coool! must try it out. thanks!

[yerpa58]

Hi synth folks,

Just in time for Halloween, I finally got that drone preset done. It is good for eerie ambient sounds. The potentiometer functions are:

pot 0 : Algorithm
pot 1 : Cross Fade Speed
pot 2 : Freq 1
pot 3 : Freq 2
pot 4 : Chorus Offset
pot 5 : Chorus Env Speed
pot 6 : Ring Mod Env Speed
pot 7 : Vibrato Speed (when vibrato is switched on)

In addition to the two oscillators, this "patch" uses four LFOs, a ring modulator, a couple envelope generators, and a dynamic chorus (delay) buffer. It will self-run in a boring way, but it is really meant to be played using the potentiometers.

I was used to hearing it thru the small 3 inch on-board speaker, and when I plugged it into a guitar amp I was pleasantly surprised at all the low frequency stuff that was in there.

This recording was mic'ed right from the guitar amp speaker, no effects added at all. Al the little skritchy sounds are from the nature of the 8-bit signal processing. Sometimes it sounds like it is being played from an old vinyl record. I did not turn on the fraktal synth's vibrato, so the weird little vibratos you hear are from the dynamic chorus buffer.

I'm posting the hex file here in case anybody wants to burn it - I'll be posting the source as soon as I get my web page updated.

Enjoy!

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2tonedrone.mp3
Description:	Just in time for Halloween - a spooky new drone from the fraktal synth	Download (listen)
Filename:	2tonedrone.mp3
Filesize:	4.89 MB
Downloaded:	855 Time(s)

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picsynth.hex
Description:	hex file for PIC 18F4620	Download (listen)
Filename:	picsynth.hex
Filesize:	24.5 KB
Downloaded:	458 Time(s)

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[oootini]

cool! must get on this!