🐰 chee cherries quiet party

entries from march 2021

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Developing for pygamer using cmake

DISCLAIMER: Sorry, this post is about boring code shit i just don't want to learnt to do again later. It's only a few things but it took me days to get a handle on.

Using cmake instead of the arduino ide is really nice, it works well in both text editors (emacs and vscode) and you get context-aware completion, hover docs, etc.

1. Get Arduino-CMake-Toolchain:

$ cd ~/projects
$ git clone <https://github.com/a9183756-gh/Arduino-CMake-Toolchain>

2. Start your project:

$ mkdir cool_project
$ cd cool_project
$ touch main.cc
$ $EDITOR CMakeLists.txt

CMakeLists.txt:

cmake_minimum_required(VERSION 3.19.0)
project(cool_project CXX)
add_executable(cool_project main.cc)

# `AUTO_PUBLIC` will automatically find and link the right libraries
# from your installed arduino libraries, just like the arduino IDE!
target_link_arduino_libraries(bleepbloopmachine AUTO_PUBLIC)

# this will add an `upload` target that you can use to build &
# upload to the microcontroller
target_enable_arduino_upload(bleepbloopmachine)

3. Use cmake!

$ mkdir build
$ cd build
$ cmake -D CMAKE_TOOLCHAIN_FILE=$HOME/projects/Arduino-CMake-Toolchain/Arduino-toolchain.cmake -D CMAKE_EXPORT_COMPILE_COMMANDS=1 ..

This will generate a compile_commands.json file that your editor can use to give you completion hints and docs.

4. Setup vscode!

If you're using Code:

  1. install the cmake tools extension.

  2. Run the command CMake: Edit User-Local CMake Kits

  3. add this kit to the array:

    {
     "name": "Arduino toolchain",
     "toolchainFile": "/home/chee/projects/Arduino-CMake-Toolchain/Arduino-toolchain.cmake"
    }

    (change the toolchainFile path to the correct path for wherever you cloned the cmake arduino toolchain to in the very first step)

  4. Run the command CMake: Select A Kit and select Arduino toolchain from the drop-down

  5. Now you can use CMake: Build (F7) and CMake: Build Target upload to build and upload things to the microcontroller!

getting the upload target working

Set the environment variable SERIAL_PORT_FILE to ttyACM0 (or whatever the microcontroller's serial port is on your computer) in the workspace's cmake.buildEnvironment setting:

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pygamer nanoloop clone pt i

I'm working on a clone of Oliver Wittchow's nanoloop for the Adafruit PyGamer.

The prototype was written in CircuitPython, which is a lovely language, but it doesn't (yet) have support for the kinds of audio things I want to do.

It was helpful to use it to lay out the shape of the state object, and the controls and the UI.

The audio was unuseable, so I've rewritten it in C++.

It's coming along very well.

There are 4 sound channels available for use, using the fab Teensy Audio Library:

  • square
  • pulse
  • sawtooth
  • noise

The **e**nv**e**lop**e** menu item let's you change the attack, decay, sustain volume, amplitude and panning of your note block with cute visual indicators of each property.

There is a filter and a delay feature, and each channel can play at full speed, half speed or quarter speed. You can alter the bpm in the second menu.

It's a lot of fun.

The plans for the next session (this evening?) are:

  • add a pitchbend envelope (for the **m**od menu item)
  • add UI for delay and filter
  • use the neopixel array on the base of the PyGamer to indicate the current bar (the loop plays for 4 bars, things on /2 or /4 speed play twice or once during that time)

Future plans are to introduce pattern chaining, pattern-length (per-channel), using square curves for attack and decay and chords (positive integer intervals).

The code is very bad and available here:

https://git.snoot.club/chee/bleepbloopmachine

It's already starting to diverge from nanoloop, and I hope it will continue to forge its own identity until it can stand strong as its own independent interesting instrument.