There's a new blog post outlining a bare bones Ecological Momentary Assessment (EMA) system on the BatAndCat support site:
https://bc-support.github.io/posts/EMA/
The example project demonstrates the basic techniques of saving data to files, setting the time on the PHL and playing sample .wav files. The source code is included, so if you're new to the PHL it could be a useful starting point for designing your own EMA.