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NES like synth on an attiny4313
DAVID Posted: 21 Nov 2019, 03:11 AM
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avrs + midi = best diy synths

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Posts: 216
Joined: 10-September 17
Ever since I saw Mitxela´s attiny2313 polysynth I became really excited with it since it was my first experience with a DIY polyphonic synth.
Now recently I tried to do something similar to it but I wanted more waveforms because lets face it squarewaves can get a little bit annoying over time, And it sounds sort of like and NES but with way more voices (8 voices).

So it has 6 different waveforms (square, sine, triangle, saw, sine + square and a brighter sine) and this are set with MIDI CC commands, just like in general midi each midi channel has its own instrument, so it is multi-timbral. It also has a white noise generator like the NES for percussion, finally it supports pitch bend.

The code only take 3kb of flash (1kb is taken by the look up tables) and just 101 bytes of ram.
I coded it in the arduino IDE but you can easy port it to a c file since it doesn´t uses any library.

Anyway here I have a demonstration video of it :https://youtu.be/-aHOWtXWFdQ
Code and schematic is in the description of the video, Hope someone likes it.

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mit Posted: 25 Nov 2019, 03:11 PM
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yeah whatever

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Joined: 4-May 16
Multi-timbral! Amazing work.

I watched the video, I love how you snuck one of my old midi files in there.

Are you aware of an old program called Gashisoft? Turns midi files into NES-like sounds. I remember trying to work out how it works, it has I think 8 different drum sounds. If there is space on the chip, you could try adding a kickdrum, snare, and so on.

I was going to suggest adding some anti-aliasing so that you could have higher-pitched notes that are clean and in-tune, but you know what you could do, since you have a proper power-supply and a crystal, you could overclock the ATtiny chip. I haven't tried it but I heard you can run them at up to 30MHz. That'd give you another octave of range...

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DAVID Posted: 25 Nov 2019, 09:11 PM
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avrs + midi = best diy synths

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Posts: 216
Joined: 10-September 17
30MHZ!!, I might give it a shot.
At first i tried to put a volume control for each channel generators and create a sort of ADSR controll, problem is that the attiny family of MCU have and infamous (at least for) behavior at doing bit shift operations, they take a lot more time to do in there compared to the atmega MCUs.
And putting drums samples I think I might just have enough space for that.

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