Finger Gap Tester

Measures the time gap between simultaneous button presses on a fighting game controller. Built for FGC players who want to understand their natural finger timing, detect stray inputs, and tune their NOBD sync window.

Download the latest FingerGapTester.exe →

No Python, no install, no dev tools. Just download, double-click, plug in your stick, and start pressing buttons. It's a single self-contained .exe — nothing else needed.

The exe is unsigned, so Windows SmartScreen may show a "Windows protected your PC" warning the first time. Click More info → Run anyway.

Two versions included:

• Windows GUI (.exe) — download above, just run it (no setup)
• Rust GUI (source) — build the native desktop app yourself with cargo
• Python CLI — lightweight terminal tool, runs anywhere with Python + pygame

• Pair detection — measures the gap (in ms) between two buttons pressed "at the same time"
• Stray press detection — flags solo button presses that didn't pair with anything (potential unwanted jabs during wavedashing)
• Bounce detection — catches switch bounce (re-press within 5ms of release)
• Pre-fire analysis — identifies pairs where the first button was solo for 1+ USB frames before the second arrived
• Off-time tracking — measures time between release and re-press for stray diagnosis
• OBD / macro detection — warns when >50% of presses have 0ms gap
• Recommended NOBD value — suggests a sync window based on your average finger gap

• Python 3.x
• pygame (pip install pygame)
• A USB gamepad/fightstick

pip install pygame
python test_finger_gap.py

1. Plug in your stick
2. Run the script
3. Press two buttons at the same time, over and over (like LP+HP for a dash)
4. The script shows gaps in real time and flags strays/bounces
5. Press Ctrl+C to see full summary stats

  #  1  Btn 0+3  gap:   3.2ms  (avg: 3.2ms  min: 3.2ms  max: 3.2ms)
  #  2  Btn 0+3  gap:   2.8ms  (avg: 3.0ms  min: 2.8ms  max: 3.2ms)
  >>> STRAY: Btn 3 solo for 52.1ms (no pair arrived)  [off-time: 89.3ms]
  #  3  Btn 0+3  gap:   4.1ms  (avg: 3.4ms  min: 2.8ms  max: 4.1ms)
  !! BOUNCE: Btn 0 re-pressed after 2.3ms off

Summary at the end includes finger gap stats, distribution histogram, pre-fire analysis, stray breakdown by button/reason, and off-time analysis.

• Rust toolchain (install from rustup.rs)
• A USB gamepad/fightstick

cd rust
cargo build --release
./target/release/finger-gap-tester    # or .exe on Windows

Gap Tester — press two buttons simultaneously to measure your finger gap:

• Live stats: pairs, average, median, fastest, slowest
• Stray count + stray rate percentage
• Bounce count, pre-fire count
• Distribution histogram
• Recommended NOBD value
• Event log with color-coded strays (red) and bounces (orange)

Button Monitor — per-button diagnostics:

• Active button indicators (light up when held)
• Stats table: press count, hold duration, repress gap
• Full event log with timing details

NOBD (No OBD) is a firmware-level sync window for GP2040-CE controllers. It groups near-simultaneous button presses so they arrive on the same USB frame — giving you reliable dashes, throw techs, and multi-button inputs without OBD macros.

This tester helps you find your natural finger gap so you can set the sync window to the right value.

MIT