PNI Components

Overview

This is a collection of components for the esp-idf build environment for ESP32 application development.

References:

• esp-idf build environment
• esp-idf component guidelines

The included components are generally re-usable and have limited coupling, allowing applications to easily use a subset of the compnoents.

Functionality covered by the components (pretty much all of these are TODOs):

• Processing:
  • Task: A simple wrapper around FreeRTOS xTaskCreate and related functions [more]. Also included:
    • TaskLambda: A task that takes a C++11 lambda for the task callback rather than requiring the developer to derive a class and override the virtual task method.
  • Fft: An embedded-optimized FFT.
    • Using fix_fft originally from here, but the basic implementation is all over the internet.
  • Queue: A thread safe FIFO. Thread safe only for push and pop.
  • LambdaQueue: A queue for lambdas to be passed safely from one task to another.
  • Actor: A task with an associated lambda queue.
  • Dispatcher: To send/receive process-wide notifications.
• Presentation:
  • FixedPoint: A template class that handles arbitrary precision fixed-point math. Handy for integer-based operations on color components for driving LEDs, but has many uses beyond that in the embedded world.
  • Color: For manipulating colors in RGB and HSV space. Includes lerp functions in both color spaces which is handy for LED animations.
  • ArrayResampler: For up and downsampling an array of data. Handy for scaling 1D image data for display on different size LED strips. Should probably make a 2D array resampler and then get 1D functionality for free.
  • Gauge: Classes to show data in various forms. Targeted for monochrome displays (i.e., OLEDs such as SSD1306), so not too fancy.
    • GaugeLinear: Bar and line graphs for 1D data.
    • GaugeRadial: Radial graph (a la speedometer or tachometer).
  • Mapper For clut to map colors between display devices. Can be used for keeping constant brightness while animating hue.
• Drivers:
  • Apa102: A simple set of classes to drive APA102 LEDs. Has an abstraction to accomodate S/W and H/W SPI. Note: Only the S/W interface is currently implemented.
  • Msgeq7: Configure and read the MSGEQ7 graphic EQ chip.
  • Max9814: Auto-gain control mic amp, used with Adafruit Electrec Mic breakout: Adafruit Electret Microphone Amplifier.

Recommended Usage

Given an application project for the esp-idf, do the following:

• Add a submodule (assuming you are using git):
  • Change directory to the root of the project
  • mkdir 3p # an example name for 3rd party code directory
  • cd 3p
  • git submodule add <repo url> pnicomponents
    • There's always a chance you might need to do a git submodule sync or init depending on your git version.
• Symbolic link desired components into build system:
  • Change directory to the root of the project
  • mkdir components # name must be 'components'
  • cd components
  • ln -s ../3p/pnicomponents/components/<some-component> <some-component>

When you do your next build, the <some-component> component will automatically be built and linked into your project. The headers from the component will automatically be available to your application code and other components.

Troubleshooting

• Issue: Build fails
  • Probably due to component dependencies. While there is minimal coupling between components in this project, some do exist and not adding a symbolic link for a dependeny in the components directory can cause this kind of failure.

About PNI

The PNI prefix is an arbitrary thing to give all the classes a namespace to avoid collisions with other libraries and system symbol names. Don't ask what it stands for.