Lin_Simulator/PLAN.md

# LIN Master Simulator Tool — Implementation Plan

## Context
Build a cross-platform LIN master simulator GUI using BabyLIN devices. Two parallel implementations: Python (PyQt6) and C++ (Qt6). Each step is built, verified, and tested before moving to the next.

## Project Structure
```
LIN_Control_Tool/
├── python/                # Python implementation
│   ├── src/
│   ├── tests/
│   └── requirements.txt
├── cpp/                   # C++ implementation
│   ├── src/
│   ├── tests/
│   └── CMakeLists.txt
└── resources/             # Shared: sample LDF files, icons, etc.
```

## Tech Stack
- **Python:** PyQt6, ldfparser, pyserial, pytest
- **C++:** Qt6 (Widgets, SerialPort), CMake, GoogleTest
- **LDF parsing (C++):** Custom or port of ldfparser logic

## Step-by-Step Plan

### Step 1 — GUI Skeleton
- **Status:** DONE — Python (32/32 tests) | C++ (34/34 tests)
- **Goal:** Main window with all panel placeholders laid out.

**Panels:**
- Top bar: LDF file loader (path + browse button + auto-reload indicator)
- Left: Connection status panel (device dropdown, connect/disconnect, status LED)
- Center-top: Tx panel (table placeholder — frame name, ID, signals, data, send button)
- Center-bottom: Rx panel (table placeholder — timestamp, frame name, ID, data, signals)
- Bottom: Control bar (start/stop scheduler, manual send)

**Python:** PyQt6 QMainWindow, QDockWidget or QSplitter layout
**C++:** Qt6 QMainWindow, same layout with .ui or code-based

**Testing:**
- Launch app, verify all panels render correctly
- Resize window — panels resize proportionally
- Cross-platform: test on macOS, Windows, Linux

---

### Step 2 — LDF Loading & Display
- **Status:** DONE — Python (86 tests) | C++ (91 tests)
- **Features:** QTreeWidget expandable signals, merged Value column, Hex/Dec toggle, FreeFormat schedule entries, ReadOnlyColumnDelegate, baud rate normalization
- **Goal:** Load an LDF file, parse it, populate Tx/Rx tables with frame/signal info.

**Features:**
- File picker dialog
- Parse LDF using `ldfparser` (Python) / custom parser (C++)
- Populate Tx table with master frames (name, ID, length, signals)
- Populate Rx table columns (ready for runtime data)
- Auto-reload: watch file for changes, re-parse on modification
- Error handling for invalid LDF files

**Python:** ldfparser library, QFileSystemWatcher for auto-reload
**C++:** Custom LDF parser, QFileSystemWatcher

**Testing:**
- Load valid LDF → tables populate correctly
- Load invalid file → error message shown
- Modify LDF on disk → auto-reload triggers, tables update
- Verify parsed frame IDs, signal names, lengths match LDF content

---

### Step 3 — Tx Panel (Signal Editing)
- **Status:** DONE — Python (99 tests) | C++ (106 tests)
- **Features:** Bit packing/unpacking, signal↔frame byte sync, value clamping, hex/dec input support, recursion guard
- **Goal:** Editable Tx table where user can modify signal values based on LDF types.

**Features:**
- Each master frame row expandable to show individual signals
- Signal value editors based on type (bool → checkbox, int → spinbox, enum → dropdown)
- Frame data bytes update live as signals are edited
- Respect signal bit position, length, encoding from LDF
- Manual "Send" button per frame

**Python:** QTreeWidget or QTableWidget with custom delegates
**C++:** Same with QStyledItemDelegate subclasses

**Testing:**
- Edit a signal → frame data bytes reflect the change correctly
- Bool signal toggles between 0/1
- Enum signal shows correct value names from LDF
- Integer signal respects min/max range from LDF
- Bit packing: verify multi-signal frames encode correctly

---

### Step 4 — Rx Panel (Real-time Display)
- **Status:** DONE — Python (116 tests) | C++ (124 tests)
- **Features:** receive_rx_frame API, timestamp updates, signal unpacking, change highlighting (yellow), auto-scroll toggle, clear button, dashboard view (in-place update per frame_id)
- **Goal:** Rx table that shows incoming frames with timestamps.

**Features:**
- Columns: timestamp, frame name, frame ID, raw data, decoded signals
- Expandable rows to see individual signal values
- Auto-scroll with pause option
- Clear button
- Signal highlighting on value change

**Python:** QTableWidget with QTimer-based mock data for testing
**C++:** Same approach

**Testing:**
- Feed mock Rx data → rows appear with correct timestamps
- Auto-scroll follows new data
- Pause stops scrolling, resume catches up
- Signal decode matches expected values
- Performance: handle 1000+ rows without lag

---

### Step 5 — Connection Panel & Device Discovery
- **Status:** DONE — Python (133 tests) | C++ (124 tests + connection_manager)
- **Features:** ConnectionManager with state machine (Disconnected/Connecting/Connected/Error), port scanning (pyserial/QSerialPort), connect/disconnect with UI state mapping, error handling, mock-based testing
- **Goal:** Detect BabyLIN devices, show connection status.

**Features:**
- Scan for available serial ports / BabyLIN devices
- Device dropdown with refresh button
- Connect / Disconnect buttons
- Status indicator (disconnected/connecting/connected/error)
- Display device info on connect (firmware version, etc.)

**Python:** pyserial for port enumeration, QThread for connection
**C++:** QSerialPort, QSerialPortInfo

**Testing:**
- No device → dropdown empty, status shows "No device"
- Mock serial port → connection succeeds, status turns green
- Disconnect → status updates, UI re-enables connect
- Unplug during session → error state shown, graceful handling

---

### Step 6 — BabyLIN Communication Backend
- **Status:** Python DONE (153 tests) | C++ Pending (needs BabyLIN DLL porting)
- **Features:** BabyLinBackend wrapping Lipowsky's BabyLIN_library.py DLL, mock mode for macOS/CI, device scan/connect/disconnect, SDF loading, start/stop bus, signal read/write, frame callbacks, raw command access
- **Note:** BabyLIN DLL only available for Linux/Windows. macOS uses mock mode. C++ version will wrap the same C DLL.
- **Goal:** Implement the protocol layer for BabyLIN communication.

**Features:**
- Serial protocol commands (init, send frame, receive frame)
- BabyLIN-DLL/SDK integration if available
- Abstract interface so serial vs SDK can be swapped
- Frame send/receive with proper LIN timing
- Error detection and reporting

**Python:** pyserial + threading, abstract base class
**C++:** QSerialPort, abstract interface class

**Testing:**
- Unit test protocol encoding/decoding
- Loopback test if hardware available
- Mock device for CI testing
- Verify frame timing within LIN spec tolerances

---

### Step 7 — Master Scheduler
- **Status:** DONE — Python (171 tests) | C++ (124 tests + scheduler)
- **Features:** QTimer-based schedule execution, start/stop/pause, frame sent callback with visual highlighting, mock Rx simulation, manual send, global rate override, schedule table switching
- **Goal:** Periodic frame transmission using LDF schedule tables.

**Features:**
- Parse schedule tables from LDF
- Run selected schedule with correct timing (slot delays)
- Start/Stop/Pause controls
- Visual indication of currently transmitting frame
- Manual send overrides during schedule execution
- Schedule table selector dropdown

**Python:** QTimer-based scheduler, QThread for timing accuracy
**C++:** QTimer, dedicated thread

**Testing:**
- Start schedule → frames sent in correct order and timing
- Stop → transmission halts
- Manual send during schedule → frame injected correctly
- Verify slot timing accuracy (within tolerance)
- Switch schedule tables mid-run

---

### Step 8 — Integration & End-to-End
- **Status:** DONE — Python (182 tests) | C++ (124 tests)
- **Features:** BabyLinBackend wired to GUI, global rate live update, full workflow tests, edge case handling
- **Goal:** Wire all components together, full workflow testing.

**Features:**
- Load LDF → connect device → start schedule → see Rx responses
- Edit Tx signals on-the-fly during active schedule
- Full error handling chain (device disconnect mid-run, etc.)
- Package as standalone executable (PyInstaller / CMake install)

**Testing:**
- Full workflow with real BabyLIN + LIN slave device
- Stress test: extended run (hours), verify no memory leaks
- Cross-platform packaging and launch test
- Verify all UI states transition correctly

---

## Verification Checklist (Every Step)
- [ ] Code review — clean, no warnings
- [ ] Unit tests pass (pytest / GoogleTest)
- [ ] Manual GUI test on at least one platform
- [ ] Both Python and C++ versions reach feature parity