Biotron MIDI: CC mapping, iPad setup, and powering synths over TRS

Biotron sends MIDI over USB. By default it sends note-on and note-off messages when it detects a signal from your plant or cables. It also sends CC90 — a continuous controller message that reflects signal intensity. This article covers what CC90 is, how to switch between note and CC output, iPad + GarageBand setup, and how to power Biotron when you connect it to a hardware synth over TRS.

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What CC90 means

When Biotron detects a signal, it sends two things at once:

• Note-on / note-off — a standard MIDI note (pitch + velocity) for triggering synths, samplers, and DAWs that respond to notes.
• CC90 — a continuous controller on the same channel, ranging from 0 to 127. It reflects how strong the detected signal is.

CC90 is not documented on the product page. That is a known gap — we get questions about it regularly. The short answer: CC90 is useful when you want smooth, continuous modulation (filter cutoff, reverb amount, expression) instead of discrete note triggers.

Example in Ableton Live: create a MIDI track, open the MIDI Map mode, click a macro knob, then touch your plant. Biotron's CC90 will be detected and mapped automatically.

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Switch between note output and CC output

By default Biotron sends both note-on/off and CC90 simultaneously. If your DAW or synth only needs one of them, mute the other in the settings page.

Steps:

1. Connect Biotron to a laptop or desktop via USB.
2. Open settings.playtronica.com/#/biotron in Google Chrome or Edge.
3. Select your Biotron from the device dropdown.
4. In the channel settings, mute Notes if you only want CC output, or mute CC if you only want note-on/off.
5. Click Send to Device.

The mute setting is stored on the device. It persists after you unplug.

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The settings page only works on desktop

If you open settings.playtronica.com on an iPad or iPhone, you will see a message that it only works on a computer. This is a browser limitation — the Web MIDI API that the settings page uses is not supported on mobile browsers or Safari.

The settings page requires:

• A laptop or desktop computer (Windows or macOS)
• Google Chrome or Microsoft Edge (not Safari, not Firefox)
• A direct USB connection (avoid USB hubs if possible)

You cannot change Biotron's settings from an iPad. If an iPad is your only device, ask someone with a laptop to connect Biotron once and apply the settings — the configuration stays on the device.

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Using Biotron with iPad and GarageBand

You can play Biotron from an iPad even though you cannot change settings from one. GarageBand on iPad receives MIDI over USB natively.

What you need:

• Apple Lightning-to-USB Camera Adapter (older iPads) or USB-C hub (newer iPads)
• The Biotron's USB cable

Steps:

1. Connect the USB adapter to your iPad.
2. Plug Biotron into the USB adapter.
3. Open GarageBand on your iPad.
4. Choose an instrument (e.g. keyboard, sampler).
5. Touch your plant or conductive object. Biotron will trigger notes inside GarageBand.

GarageBand does not display MIDI channels or CC values. It simply plays the instrument assigned to the current track. If you hear nothing, check that GarageBand's track is set to receive MIDI from external sources — tap the track, tap the plug icon, and make sure MIDI input is enabled.

If Biotron lights up but produces no sound, the notes channel may be muted. You will need to borrow a laptop to open settings.playtronica.com and re-enable notes.

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Powering Biotron when using TRS MIDI

Biotron connects to most DAWs and computers over USB, which provides both data and power. When you connect Biotron to a hardware synthesizer using a TRS MIDI cable (3.5 mm stereo jack to standard 5-pin DIN), the synth receives MIDI data — but the TRS cable carries no power.

This means Biotron will not turn on using a TRS cable alone.

Solution: power Biotron separately over USB while sending MIDI via TRS.

You need a USB power source that does not also try to send MIDI data. Any of these work:

• A USB wall adapter (5 V, any current rating)
• A USB battery pack
• A powered USB hub (use a separate port from the TRS adapter)

Setup:

1. Plug the TRS MIDI cable into Biotron's TRS port.
2. Plug the other end into your synth's MIDI In.
3. Plug a USB power cable into Biotron's USB port.
4. Connect the USB cable to a wall adapter or battery pack — not to your computer. Connecting to a computer at the same time will route MIDI over USB instead of TRS.
5. Power on everything. Biotron's LED will light. Touch your plant. Your synth should receive the note-on messages.

If your synth still receives no MIDI, check whether it expects TRS Type A or TRS Type B. Biotron uses Type A (compatible with Arturia MiniLab, Teenage Engineering OP-1, most modern gear). If your synth uses Type B, you need a Type A–to–Type B adapter.

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Quick self-test

Press the fingerprint button on Biotron. The device sends a short burst of MIDI notes on channel 2. If your DAW or MIDI monitor shows those notes, the device is working and the problem is in your connection or DAW routing — not the hardware.

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Still stuck?

Email [email protected] with:

• A short video showing the full connection and what happens when you touch the plant
• Your operating system and DAW name
• Whether the self-test (fingerprint button) produces notes in your MIDI monitor