Bela

Pure Data

1. Power and connect Bela

Connect the Bela board to your computer via USB. Bela runs its own embedded Linux system and creates a USB network interface — no driver installation is required on macOS or Linux. On Windows, install the RNDIS driver if prompted.

Once connected, open a browser and navigate to:

http://bela.local

This opens the Bela IDE, a browser-based environment for writing and running code directly on the board.

2. Enable Pure Data on Bela

In the Bela IDE, click the language selector at the top right of the editor. Select Pure Data from the dropdown. The IDE will switch to PD mode and expect a _main.pd file as the entry point.

3. Create your first patch

In the IDE, create a new file named:

_main.pd

This is the required filename — Bela will look for this file specifically when running in Pure Data mode. Build your patch using standard PD objects. Bela exposes its analog and digital I/O through the [bela~] and [bela-ai~] objects.

Basic audio passthrough example:

[adc~ 1 2]
|
[dac~ 1 2]

4. Set audio settings

In the Bela IDE, go to Settings (gear icon). Set the sample rate and block size:

Sample rate: 44100 Hz (or 48000)
Block size: 16 (lower = less latency, more CPU load)

Bela's audio interface is built in — no external soundcard configuration is needed.

5. Run the patch

Click the Run button (▶) in the IDE. The patch compiles and launches on the board. Audio output is available immediately via the Bela's 3.5mm stereo jack or the onboard stereo output pins.

To stop the patch:

Click Stop in the IDE, or send SIGINT via SSH

6. Autorun on boot

To make the patch run automatically every time Bela powers on, click the Run on boot button in the IDE toolbar. Bela stores the project and launches it at startup without needing a computer connection.

To verify autorun is set via SSH:

ssh root@bela.local

Check the active project:

cat /root/Bela/projects/active_project

To disable autorun, clear the active project field in the IDE settings or run:

echo "" > /root/Bela/projects/active_project

7. Transfer patches from desktop Pure Data

Patches built in standard Pure Data are compatible with Bela's Pd runtime with minor adjustments. Upload files via the IDE file manager (drag and drop into the project panel) or via SCP:

scp your-patch.pd root@bela.local:~/Bela/projects/your-project/

Rename or copy to _main.pd once uploaded, then press Run.