shroud-of-turing

This release brings four significant new features — the largest update to the Shroud of Turing since its initial release.

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What's New

1. Machine State Save / Recall — 5 Slots

The biggest new feature in this release. You can now save and instantly recall the complete state of the module to any of five slots, mapped to the black keys (C#, D#, F#, G#, A#).

To save: Hold Octave Down (long-hold) then press any black key.
To recall: Hold Octave Up (long-hold) then press any black key.

Each slot captures the complete module state:

• Shift register pattern
• Sequence length
• Voltage range and window offset
• Active quantization scale
• Sequence rotation offset
• Probability pot position
• Slew/portamento amount Recalling a state is immediate and seamless — the pattern, scale, and all settings are restored instantly. If the state was saved in LOCKED or DOUBLE mode, reset and rotation work the moment it loads, with no need to move the potentiometer first.

State data is stored in EEPROM and survives power cycles.

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2. Portamento / Slew

Smooth glide between CV output notes is now available in Turing Machine mode.

To adjust: Hold SHIFT and turn the potentiometer.

• Fully counterclockwise = instant (no glide)
• Clockwise = increasing glide time While SHIFT is held, probability is frozen and the pot controls slew exclusively. When SHIFT is released, the pot returns to probability control. Both transitions use pickup protection to prevent accidental jumps.

Slew amount is saved and restored with machine state.

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3. Voltage Window Shift

The output voltage window can now be repositioned across the 0–4V space using Shift + Octave Up / Shift + Octave Down. The window slides in 1V steps and stops hard at the boundaries.

• A 1-octave window at offset 0 = C0–C1
• A 1-octave window at offset 1 = C1–C2
• A 1-octave window at offset 2 = C2–C3
• A 1-octave window at offset 3 = C3–C4 Works with any window size — a 2-octave window shifts 0–2V → 1–3V → 2–4V. Quantized output shifts by whole octaves through the calibration table; unquantized output shifts linearly. Expanding the range via normal Octave Up automatically pushes the window down if needed to keep the top within 4V. Window position is saved and restored with machine state.

CV Keyboard mode is unaffected — it retains its own independent octave logic.

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4. Single Note Removal from Scale

Individual notes can now be removed from the active quantization scale without clearing the entire scale.

To remove a note: Long-hold any note button for 800ms.
To add a note: Short press as before.

Long-hold removal is blocked when Shift or either Octave long-hold is active, preventing interference with save/load operations.

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Bug Fix

State Load Immediately Restores Lock / Double Mode

When loading a state saved in LOCKED or DOUBLE mode, the sequencer previously remained unlocked until the potentiometer was moved past the pickup threshold — meaning Shift + C# (reset to first note) had no effect immediately after a load.

This is now fixed. Lock and double mode are restored the moment a state is recalled, with no pot movement required.

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Save / Load State — Technical Note

State slots use a 14-byte EEPROM layout with signature 0xB3B3. Each slot stores pattern, step length, rotation offset, voltage range, window offset, scale, probability snapshot, and slew amount. Five slots occupy addresses 118–187, safely within the platform's allocated space and well clear of the protected calibration region.

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Full Changelog

See CHANGELOG.md for the complete version history.

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Firmware: ShroudOfTuring_v1_2_7.ino
Platform: Nocturne Alchemy Platform (Arduino Nano)
Requires: Arduino IDE with Adafruit MCP4725 library

Shroud of Turing v1.2.0

Turing Machine MKII-style random sequencer with musical quantization for the Nocturne Alchemy Platform.

What's in this release

• ShroudOfTuring_v1_2_0.ino — Source code (in the firmware/ folder)
• ShroudOfTuring_v1_2_0_User_Manual.pdf — Full user manual (in the docs/ folder)

Installation

1. Download the source code below
2. Open firmware/ShroudOfTuring_v1_2_0.ino in Arduino IDE
3. Select Board: Arduino Nano, Processor: ATmega328P (Old Bootloader)
4. Upload to your Nocturne Alchemy Platform module

Read firmware/shared_libraries/README_SHARED_LIBRARIES.md before modifying anything — the shared libraries manage your factory calibration data.

Requires

• Nocturne Alchemy Platform hardware (proprietary — not included)
• Adafruit_MCP4725 library (Arduino Library Manager)