Crash - 8bit Firmware

This 8bit firmware generates a TR-808-style crash cymbal. Unlike sample-based drums, the crash is synthesized entirely in real time — rendered inside a timer interrupt and written straight to the 8-bit DAC audio output.

It responds to MIDI note-on messages with a short, self-decaying metallic ring. The crash rings out on its own instead of hanging for the full gate, so even a long held note gives you a short, punchy crash.

Features#

• Synthesized Crash Cymbal: TR-808-style crash rendered in real time on the ATtiny1616 — not sample-based
• Self-Decaying Ring: The sound rings out on its own instead of sustaining for the length of the gate
• Velocity Sensitive: Note velocity controls the loudness of the crash
• CV Inputs:
  • CV1 for metallic pitch/brightness/color
  • CV2 for hiss/metal balance
• CV Motion Recorder: Record a four-bar CV performance on the MIDI-clock grid and auto-loop it
• LED Indicator: Shows the motion recorder state (blinks while recording, solid during playback)

Installation#

8bit contains a ATTINY 1616 MCU. To program & install the firmware follow this guide.

The firmware is located at modules/8bit/code/crash in the code repository.

Controls#

MIDI Control#

The crash is triggered via MIDI:

• Note On: Fires the crash cymbal. Every note triggers the same crash (note data is ignored)
• Velocity: Controls the loudness of the hit

CV Inputs#

CV1 (Metallic Pitch)

• Function: Sets the base frequency of the inharmonic partials
• Range: 80 Hz to 1200 Hz
• Behavior: Shapes the pitch, brightness, and overall color of the metallic ring
• Always Active: Changes are applied continuously while playing

CV2 (Hiss/Metal Balance)

• Function: Blends between the tonal metal ring and sizzle/hiss noise
• Behavior:
  • At minimum, you hear a pure tonal metal ring
  • As CV2 increases, more sizzle/hiss noise is blended in
• Always Active: Sweep CV2 during playback for evolving cymbal textures

Audio Output#

The synthesized crash is rendered to the single 8-bit DAC audio output.

CV Motion Recorder#

The crash firmware includes the same CV motion recorder as the Monosynth app on 16bit. Click the MODE button to record and loop your CV movements:

1. LIVE - The default state. CV1 and CV2 directly control the crash.
2. RECORDING - Click MODE once. The LED blinks and a four-bar take of CV1/CV2 values is recorded on the MIDI-clock grid.
3. PLAYBACK - When the take completes, the LED turns solid and the recorded CV performance auto-loops. Click MODE again to return to LIVE.

Clicking MODE while still recording discards the partial take. MIDI Start rewinds the active loop. Just like recording, playback requires a running MIDI clock.