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ChipMusic.org / Forums / Posts by Trash80
This sounds awesome. Can't wait to see what it looks like. \O,o/
Well right now it's just a sparkfun midi shield and a resistor network for the DAC soldered to it. 
I can't want to start on the tiny interface using this guy:
Preorder?
New Order.
oh and I'm gonna add LAZERZ. pewpewpepwpewpew
So I've been working on a synth on and off for the last 2 years. It's finally starting to take shape and once I finish sourcing parts and figuring out the audio opamp/output circuit and interface I'll be releasing it.
Thought I'd share my progress so far:
It's a 4bit synth that doesn't use a static sample rate frequency to generate the synthesis sound- therefor it doesn't have the usual artifacts from low sample-rate dsp so that no aliasing is generated, and no anti-aliasing algorithm is needed.
Originally built on the Arduino- I moved it to the ARM-based Leaflabs Maple to take advantage of the faster clock for higher pitches.
It currently has 3 synthesis types:
1. 32 step wave synth with digital filter (kind of like the LSDJ wav synth)
2. 128 step PWM synth
3. 256 step LFSR noise generator (like a gameboy or NES noise- only the pitched noise is in tune)
All modes have a sub oscillator & oscillator sync to give it some extra tonal quality. I really liked the idea of a LFSR noise generator with oscillator sync.
I'm just about done with main synthesis code and am about to start on an interface. Been thinking about using a 4dsystems tiny tiny OLED display module and a single pushbutton/encoder knob, as well as 4bit sample playback and storage using a micro sd reader.
Here is the demo of it I recorded this weekend, be sure to download the original waveform- soundcloud/mp3 conversion added artifacts. http://soundcloud.com/trash80/codename-sqrt-synth-test
\o/
If the lights flash to incoming midi data than the sparkfun shield's midi circuit is working. Also how did you change the pin numbers for the gameboy data pins in the code? It is all done by sending data directly to the port so I'd imagine you'd have to do quite a bit in a few places ie ... from:
if(send_byte & 0x80) {
PORTC = B00000010;
PORTC = B00000011;
} else {
PORTC = B00000000;
PORTC = B00000001;
}to this:
if(send_byte & 0x80) {
PORTC = B00001000;
PORTC = B00001100;
} else {
PORTC = B00000000;
PORTC = B00000100;
}Have you tried having it plugged into usb just for power and still use the MIDI input?
No. Arduinoboy sends a note # that corresponds to the row # you started on when the clock starts (when you hit start) on MIDI channel 16. I should of had that as a option and not always on, for dumb devices that respond to all MIDI channels. You can comment out that code or remove that code, it's 3 lines in the "Mode_LSDJ_MasterSync" tab when you open up the arduinoboy code in the arduino software. At the bottom of the file you'll see this:
/*
sendMidiClockSlaveFromLSDJ waits for 8 clock bits from LSDJ,
sends the transport start command if sequencer hasnt started yet,
sends the midi clock tick, and sends a note value that corrisponds to
LSDJ's row number on start (LSDJ only sends this once when it starts)
*/
void sendMidiClockSlaveFromLSDJ()
{
if(!countGbClockTicks) { //If we hit 8 bits
if(!sequencerStarted) { //If the sequencer hasnt started
Serial.write((0x90+memory[MEM_LSDJMASTER_MIDI_CH])); //Send the midi channel byte
Serial.write(readGbSerialIn); //Send the row value as a note
Serial.write(0x7F); //Send a velocity 127
Serial.write(0xFA); //send MIDI transport start message
sequencerStart(); //call the global sequencer start function
}
Serial.write(0xF8); //Send the MIDI Clock Tick
countGbClockTicks=0; //Reset the bit counter
readGbSerialIn = 0x00; //Reset our serial read value
updateVisualSync();
}
countGbClockTicks++; //Increment the bit counter
if(countGbClockTicks==8) countGbClockTicks=0;
}change it to this:
/*
sendMidiClockSlaveFromLSDJ waits for 8 clock bits from LSDJ,
sends the transport start command if sequencer hasnt started yet,
sends the midi clock tick, and sends a note value that corrisponds to
LSDJ's row number on start (LSDJ only sends this once when it starts)
*/
void sendMidiClockSlaveFromLSDJ()
{
if(!countGbClockTicks) { //If we hit 8 bits
if(!sequencerStarted) { //If the sequencer hasnt started
Serial.write(0xFA); //send MIDI transport start message
sequencerStart(); //call the global sequencer start function
}
Serial.write(0xF8); //Send the MIDI Clock Tick
countGbClockTicks=0; //Reset the bit counter
readGbSerialIn = 0x00; //Reset our serial read value
updateVisualSync();
}
countGbClockTicks++; //Increment the bit counter
if(countGbClockTicks==8) countGbClockTicks=0;
}As far as battery vs usb vs wallwart, that shouldn't matter, as long as the battery or wallwart is supplying enough power.
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Thanks and have a wonderful life.
Now this app looks interesting! Also a forum interface would be good, since reading stuff up on an iPhone browser, for example, is rather annoying.
one of those things I want to get to, is redoing our css, and adding mobile css support in the process.
Also, if you are restricted to the rss feed's xml data, maybe I should provide a better xml output exclusively for your app. Say with more data such as rating and/or comments and/or api so the user can add to their online bookmarks and such.
If the app is free, I have no problem using our icon and bandwidth. 
Try swapping the lines on the midi out? Think thats a typo on my schematics. Shit is confuse to remember and get right.
Skrillex
trash80 wrote:I can hear small amounts of fuckup with the pitchbends though, which goes into what I was saying. Ableton sends shit like 45 45 45 45 45 45 45 ... 46 46 46 46 46 46 46 46 .... 47 47 47 47 47 47 47 47 ... [...] as oppose to just those changed values once. hehe.
Does it do this even when you use the pencil? I Mean, if there's a straight line with no changes, does it still send out the same message over and over?
Nope. It's just because you are drawing a floating point line across values of a 7 or 14bit resolution. So rounded down it would take 14.124 14.125 into 14 14. etc.
Clearly not, if you hear the audio I posted of the same project: http://kikencorp.com/stuff/mGB_test_01_Rendered.mp3 (jump to 0:59 for the fun)
HAHAHA, its drunk!
I can hear small amounts of fuckup with the pitchbends though, which goes into what I was saying. Ableton sends shit like 45 45 45 45 45 45 45 ... 46 46 46 46 46 46 46 46 .... 47 47 47 47 47 47 47 47 ... [...] as oppose to just those changed values once. hehe.
I saw the video, this demonstrates arduinoboy works fine, as I expected. Thanks for that.
Oh nice, so the problem isnt with mGB?
Yeah, it takes a bit of editing to make slow pitch bends sound right, I have a max4live effect I use to help filter data. Maybe I should publish it here soon.
ChipMusic.org / Forums / Posts by Trash80