Autogenerator for Faust on Teensy

Prerequisites

• PlatfromIO: This project is build around PlatfromIO and its toolchain
• Python: The project use python to enable pre-scripts and code Generation
• Python cogapp: code generation inside the source file

Basic Usage

1. Clone the repo
2. Put your Faust program as FaustInstrument.dsp in the root directory.
3. (optional) configure your environment in platformio.ini
4. Run PlatformIO on CLI, -e specifies your custom environment, -t upload executes the flashing step after compiling

pio run -e teensy41 -t upload

Features supported via Faust Metadata

Menu IO

Add Units to values. Example:

a  = hslider("attack[unit:s]", 0.01, 0, 5, 0.01);

Set a fine-tune value. Example:

freq_offset1  = hslider("foff1[fine:0.01][unit:semitones]", 0, -12, 12, 1);

Group elements to put them in a submenu. Example:

AmpEnv(x) = vgroup("AmpEnv", x);

a = AmpEnv(hslider("attack[unit:s]", 0.01, 0, 5, 0.01));
d = AmpEnv(hslider("decay[unit:s]", 0.01, 0, 5, 0.01));
s = AmpEnv(hslider("sustain[unit:%]", 0.98, 0.001, 1, 0.01));
r = AmpEnv(hslider("release[unit:s]", 0.01, 0, 5, 0.01));

Generate a menu to select values for a slider/entry/etc. Example:

osc_sel1 = hslider("osz1[style:menu{'Sine':0;'Triangle':1;'Saw':2;'Square':3;'Noise':4}]", 0, 0, 4, 1);

Sensor data

Access analog data. It will automatically scaled to be in your selected range. Example (reads from analog input 10):

light = nentry("lightSens[io: A10]", 0, -1, 1, 0.1);

If you connect an MPU 6050 to the second I2C port of a Teensy (Pins 17/16 on Teensy 4.0/4.1) it is possible to use the gyroscope or accelerometer. The parameter is the Axis. It is scaled to fit the given range. Example:

gyro = nentry("gyroSens[gyr: 1]", 0, -1, 1, 0.1) : si.smoo;
acc = nentry("acceSens[acc: 1]", 0, -1, 1, 0.1) : si.smoo;

Platform configuration

It is possible to configure different options of the hardware platform in the platformio.ini file. They are available as preprocessor defines. Example environment configuration:

[env:teensy41]
platform = teensy
board = teensy41
framework = arduino
build_flags = -D USECLICKENCODER -D USELCD -D USB_MIDI_SERIAL -D USESPDIF -D USBHOSTMIDI
lib_deps = 
	neu-rah/ArduinoMenu library@^4.21.3
	soligen2010/ClickEncoder@0.0.0-alpha+sha.9337a0c46c
extra_scripts = 
	pre:pre_script.py

The build_flags contain these parameters. The -D sets a parameter as defined. USB_MIDI_SERIAL is a parameter of the Teensy platform. You can find more information here. The other parameters are described in the next section.

Available Parameters

Some parameter configurations might be incompatible with each other. You have to make sure to select the ones that make sense.

Menu IO

• USECLICKENCODER - use an encoder on input 3, 2 and button on input 5
• USELCD - use an HD44780 style LCD
• USEU8G2 - use an OLED Display
• USEBUTTON - use buttons on inputs 2, 3, 4 and 5
• INVERTFIELDKEYS - invert direction for field keys, might be necessary for some inputs

MIDI

• USBHOSTMIDI - use a MIDI device connected to the Teensy's Host USB Port
• USBCLIENTMIDI - use MIDI Input on USB MIDI Device (Teensy needs to be in USB MIDI Mode)
• HARDWAREMIDI - use a Hardware MIDI interface on Serial 4

Audio

• SGTL5000 - use the SGTL5000 on a Teensy audio board
• USESPDIF - use SPDIF Output on Pin 7

Example Circuit for converting the SPDIF Signal

Debug

• DEBUGOUT - print debug statements on USB Serial device (Teensy has be configured to work as a USB Serial Device), waits with program execution until the serial is opened on the Computer

File Structure

• platformio.ini - configure environments
• FaustInstrument.dsp - Faust program
• pre_script.py - python script to convert Faust code
• src/main.cpp - C++ skeleton
• src/main.py - python cogapp code