Penrose Quantizer Firmware

This is the sourcecode for the Sonic Potions Penrose Quantizer eurorack module. The project page with more information about the module can be found here: http://www.sonic-potions.com/penrose

Penrose is a simple CV quantizer DIY kit for the eurorack format. It takes an incoming continuous CV voltage and converts it to the nearest note in a scale. Active notes can be selected with the 12 buttons. You can use it to tune the output of your analog sequencer, as a semi random melody generator, for fast chiptune arpeggios and much more.

The code has multiple separate parts:

The app directory contains the Quantizer AVR main program
The drivers directory contains AVR peripheral drivers for use by the main program
The Bootloader directory contains an audio bootloader for the AVR and a C++ program to generate .wav files from AVR .hex files
The root directory contains makefiles for building each part

Changes in this fork

The bootloader has been left as is but the application has been heavily refactored.

Ported everything to C++.
Moved to a sample-rate-based architecture instead of loop-based. The sample rate is 8 kHz, and the theoretical maximum is 12 kHz (limited by the ADC).
Changed the quantizer behavior to find the nearest enabled note, instead of the nearest higher.
Optimized drivers.
Fixed a lot of bugs, some that caused crashing and some that only caused misbehavior.
Replaced the build system with boilermake. All build artifacts now go into the 'build' directory.

Installation

Download hex and wav files from Releases.

With wav file

See the Penrose manual for details on how to install firmware via the audio bootloader.

With hex file

Use the following avrdude commands to flash a chip with the firmware.

avrdude -B100 -c PROGRAMMER -P PROGRAMMER_PORT -p atmega168 \
    -U lfuse:w:0xff:m -U hfuse:w:0xd4:m -U efuse:w:0x02:m
avrdude -B1 -c PROGRAMMER -P PROGRAMMER_PORT -p atmega168 \
    -U flash:w:PATH_TO_HEX:i
avrdude -B1 -c PROGRAMMER -P PROGRAMMER_PORT -p atmega168 \
    -U lock:w:0x0F:m

You will need to replace PROGRAMMER and PROGRAMMER_PORT with the appropriate values for your AVR programmer, and PATH_TO_HEX with the path to the downloaded hex file.

Building from source

Dependencies: gcc-avr, avr-libc, python3, python3-intelhex

After cloning the repository, be sure to grab the submodules as well by running git submodule update --init --recursive

From the root directory, run make merge to generate a hex file containing both the bootloader and application. The file is written to build/artifact/penrose.hex.

Some other make targets are:

load : program a chip with the merged hex file (requires avrdude)
wav : generate a wav file for use with the audio bootloader (requires gcc)
cog : regenerate lookup tables (requires Python 3 cogapp package)
check: run unit tests (requires Google Test)

License

The code is released under the GPL:

This file is part of the Penrose Quantizer Firmware.

The Penrose Quantizer Firmware is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

The Penrose Quantizer Firmware is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with the Penrose Quantizer Firmware. If not, see http://www.gnu.org/licenses/.