Arduino library for reading an array of photocell (LDR) sensors with a sliding-window moving average and configurable threshold detection — supports multiple sensors with individual sample rates.

Non-blocking, interrupt-driven Arduino library for the VLSI VS1053 audio decoder chip — streams MP3, AAC, Ogg Vorbis, FLAC, WMA, and WAV from SD card over SPI.

Arduino library for measuring free RAM at runtime — critical for debugging out-of-memory crashes on AVR boards with as little as 2 KB of RAM.

The original non-blocking, interrupt-driven Arduino library for the SparkFun MP3 Player Shield (VS1053) — superseded by the generalized vs1053_for_SdFat library.