Connect your NeoTrellis to a powered speaker using the built in 3.5mm stereo jack and start pressing some buttons. Press multiple buttons at the same time to create interesting combinations. Note that if 3 or more buttons are pressed at the same time, some distortion will occur on the output signal.
For the purposes of expressive experimentation, below are two alternate .UF2 files which use different note patterns. Choose one and load it onto the NeoTrellis just like you did with the previous UF2. Remember to double-click the reset button to enter firmware mode!
Arpy can also send MIDI data over USB, so you can use software synthesizers to generate sound from your computer. To use it, download the MIDI enabled UF2 file below, and upload it to your NeoTrellis just as before.
Once the NeoTrellis has restarted with the new firmware, connect your NeoTrellis M4 to your computer via USB and open your preferred music software, such as Garageband, Logic, Ableton Live, etc. The NeoTrellis should appear as a MIDI input device, just like a MIDI keyboard.
Advanced users can customize the arpeggiator parameters by editing the source code in Arduino IDE. To do so, you'll need the Arduino IDE installed on your computer, along with the libraries specified here in the NeoTrellis M4 guide. Project code is available here on GitHub, with the most common customizable parameters located in the