Arduino Uno + C# GUI — Single-Pulse Laser Trigger (Small, Well-Defined Task)

Description: I need a simple system to fire a single TTL trigger pulse to a laser module, controlled from a Windows desktop GUI. This is a small, well-scoped task — should be quick for an experienced Arduino/C# developer. Hardware: I have an Arduino Uno R3, but any similar AVR-based Arduino board (Nano, Uno R4, Mega, etc.) is fine if you prefer to develop/test on your own board first — final verification will be on my Uno R3 via remote demo. Requirements: Arduino firmware (C/C++, custom serial protocol — no Firmata): Serial commands: SET msec (set pulse width), FIRE (output single HIGH pulse of the set width, then LOW), STOP (force LOW immediately) Pulse width range: 100–2000 ms, clamped in firmware Digital output pin must default to LOW on power-up/reset (important — must never fire unintentionally) C# Windows GUI (WinForms or WPF): COM port selection (auto-detect/refresh) Numeric input for pulse width (100–2000 ms, default 500ms) "Fire" button sends SET + FIRE Emergency Stop / Laser Off button — large, red, visually separated from the Fire button. Sends STOP immediately (no confirmation dialog). After Stop, Fire button remains active and can be pressed again right away (no re-arm step needed). Status display (connected/disconnected, last-fired confirmation) Basic error handling (port not found, no response, timeout) Deliverables: Arduino .ino sketch C# GUI source code, buildable, with brief README Compiled, ready-to-run .exe (Windows), including any required runtime/dependency notes Short remote demo/handover call Out of scope: Firmata/StandardFirmata, repeating/burst pulse modes, multi-channel triggering, sub-millisecond precision, physical safety circuit design (software-only project).