munshkr/picopico

:headphones: ATtiny85-based chiptune player

picopico ピコピコ

A very small chiptune synthesizer and player. Sound is made with an 8-bit microcontroller (Attiny85) and tries to mimic a classical sound chip used in video game consoles from the 80s.

Pretty much inspired by 1-bit symphony by Tristan Perich and lft/kryo's project.

Hardware

• AVR ATtiny85
• CR2032 coin cell battery
• 1K resistor
• 0.1uf capacitor
• 3.5mm audio jack
• Push button

Schematic

Note: This schematic is old and inaccurate (although similar). Please see this tutorial as the protoboard picture reflects more accurately the current design.

Software

• Music written in an MML-like language
• HTML5 editor with sound emulator

To do

• Change current parser for a standard MML parser

> AB cdefg4 l8 >cde<c o5 r c

• Implement Square waveform for voice 1 and 2
• Implement Noise waveform for voice 3
• Envelopes!
• Work on MML compiler and editor

License

Schematic and original source code made were taken from a series of blog posts by David Johnson-Davies.

Schematic image is licensed under Creative Commons 4.0. Source code is licensed under GPLv3.

picopico's Issues

Implement a fast multiplication routine

The ATtiny85 has no hardware multiplication support, needed for the envelope generator.

Try out some of these. There's not much room for big tables, but for 8x8 mult only 512 bytes of progmem are needed (256 16bit values).

http://stackoverflow.com/questions/29935050/tinyavr-best-known-multiplication-routines-for-8-bit-and-16-bit-factors

Compress song data

Check if this is useful: a fast decompression algorithm for embedded devices with low RAM.
http://www.excamera.com/sphinx/article-compression.html