Feature Idea: 🎮 Android Button Panel → Virtual HID Device for DCS World

[arn-c0de]

Type: Feature Request / Experimental Evaluation
Status: 🔬 Testing in Progress
Priority: Medium

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📋 Description

Implement a system that allows application to act as a configurable button panel for DCS World by transmitting input events over UDP connection back to forward_parsed_udp.py .

This document also serves as an experimental evaluation to determine whether the Virtual HID approach is better and easier suited than direct Export.lua commands for the application and every Module Aircraft.

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🏗️ Proposed Architecture

Option A: Virtual HID Device (Current Experiment)

┌──────────────┐    UDP/AES-GCM    ┌──────────────┐    HID Driver    ┌───────────┐
│   📱 Android │ ────────────────► │  🐍 Python   │ ───────────────► │ 🎮 DCS    │
│   Button App │                   │   Backend    │                  │   World   │
└──────────────┘                   └──────────────┘                  └───────────┘
                                   (vgamepad/uinput)                 (Std Joystick)

Option B: Direct Export.lua (Comparison)

┌──────────────┐    UDP/AES-GCM    ┌──────────────┐   Export.lua    ┌───────────┐
│   📱 Android │ ────────────────► │  🐍 Python   │ ───────────────► │ 🎮 DCS    │
│   Button App │                   │   Backend    │                  │   World   │
└──────────────┘                   └──────────────┘                  └───────────┘
                                   (Lua Socket)                      (LoSetCommand)

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⚖️ Comparison Matrix

Kriterium	Virtual HID	Export.lua
DCS Native Binding UI	✅	❌
Works with other games	✅	❌
No Lua scripting needed	✅	❌
Module-specific commands	❌	✅
No virtual device setup	❌	✅
Lower abstraction layers	❌	✅
Portable solution	✅	❌

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📦 Scope

✅ In Scope

• New Kotlin module with configurable buttons, switches, encoders
• Bidirectional UDP communication
• Secure channel: ECDH key exchange + AES-GCM encryption via forward_parsed_udp.py and crypto_handshake.py
• Python backend exposing virtual HID device
• DCS World recognition as standard input hardware
• Cross-platform backend (Windows/Linux)
• Working also in other games (MSFS , XPLANE etc)

❌ Out of Scope

• Android as direct USB HID (no root/custom kernel)
• Reverse engineering of DCS internals
• Macro functionality (1 event = 1 HID input)

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📐 Requirements

Requirement	Target	Status
End-to-end latency	< 10 ms	⏳
Event mapping	1:1 (no macros)	⏳
Device identification	Fixed VID/PID	⏳
License compliance	Apache/BSD/MIT only	⏳

🖥️ Platform Support

Platform	Implementation	Library
Windows	ViGEmBus	vgamepad
Linux	uinput/evdev	evdev

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✅ Acceptance Criteria

• Android button press visible in DCS as costumizable modular joystick button
• Secure channel established automatically on startup
• System runs reliably for extended sessions (8h+)
• No control inputs gone lost
• No conflicts with physical input devices

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🧪 Test Cases

Phase 1: Infrastructure Setup (if use seperate .py forwarder)

• 1.1 — Python backend stable on Windows (ViGEmBus)
• 1.2 — Python backend stable on Linux (uinput)
• 1.3 — Virtual joystick visible in Windows Game Controllers
• 1.4 — Virtual joystick visible in jstest/evtest (Linux)
• 1.5 — Fixed VID/PID persists across restarts
• 1.6 — ECDH key exchange successful
• 1.7 — AES-GCM packets decoded correctly

Phase 2: Basic HID Functionality

• 2.1 — Single button press registers
• 2.2 — Button release handled correctly
• 2.3 — Multiple simultaneous presses work
• 2.4 — Latency < 10 ms (button → HID event)
• 2.5 — No event loss at 10 Hz
• 2.6 — No event loss at 50 events/sec burst

Phase 3: DCS World Integration

• 3.1 — DCS detects virtual joystick in Controls
• 3.2 — Button bindable via DCS UI
• 3.3 — Bound button triggers correct action
• 3.4 — Binding persists across DCS restarts
• 3.5 — No conflict with physical joysticks
• 3.6 — ✈️ F/A-18C Hornet tested
• 3.7 — 🛩️ A-10C II tested
• 3.8 — 🚁 Ka-50 tested

Phase 4: Stability & Edge Cases

• 4.1 — Stable over 2h session
• 4.2 — Stable over 8h session
• 4.3 — Reconnect after app backgrounded
• 4.4 — Reconnect after network interruption
• 4.5 — Graceful backend restart handling
• 4.6 — No memory leaks (24h test)
• 4.7 — CPU usage < 5% idle / < 15% active

Phase 5: Export.lua Comparison 🔬

• 5.1 — Export.lua socket connection works
• 5.2 — LoSetCommand() executes externally
• 5.3 — Measure latency: UDP → Export.lua → action
• 5.4 — Module-specific commands work (e.g., UFC)
• 5.5 — GetDevice() cockpit manipulation works
• 5.6 — Compare latency: HID vs Export.lua
• 5.7 — Compare reliability: 1000 events test

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📊 Measurement Log

Test	Date	Result	Latency	Notes
2.4		⏳	— ms
5.3		⏳	— ms
5.6		⏳	— ms

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🛠️ Implementation Checklist

📱 Android App

• Button grid UI
• Button configuration (label, ID, type)
• UDP socket management
• ECDH key exchange (client)
• AES-GCM encryption
• Connection status indicator
• Reconnect logic
• Haptic feedback
• Config save/load (JSON)

🐍 Python Backend

• Async UDP server
• ECDH key exchange (server)
• AES-GCM decryption
• Event queue management
• Windows: ViGEmBus integration
• Linux: uinput integration
• Button mapping config (JSON/YAML)
• Structured logging
• Systemd service (Linux)
• Windows service wrapper

🎮 DCS Integration

• Virtual device recognition
• Test binding profile
• Module preset profiles
• User documentation

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🔮 Future Extensions

• Configurable button-to-HID mapping (JSON/YAML)
• Multi-device support
• Encoder and axis support
• Heartbeat and reconnect handling

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📌 Current Status

Phase	Status
Infrastructure	⏳In Progress
Basic HID	⏳ Open
DCS Integration	⏳ Open
Stability	⏳ Open
Comparison	⏳ Open

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