# Host Application

C++ application running on the LattePanda's Linux side. Handles camera acquisition, serial communication with the Arduino firmware, and MQTT-based remote control.

## Dependencies

| Library | Purpose |
|---------|---------|
| **Vimba SDK** | Camera control (Allied Vision / FLIR) |
| **Eclipse Paho MQTT C/C++** | MQTT client for telemetry and remote commands |
| **OpenCV 4** | Image processing and codecs |
| **libjxl** | JPEG XL image encoding |
| **Boost** | Program options, ASIO (serial), Spirit (parsing), threading |

Install system packages (Debian/Ubuntu):
```bash
sudo apt install libboost-all-dev libopencv-dev libjxl-dev libpaho-mqttpp3-dev libpaho-mqtt3-dev
```

Vimba SDK must be installed separately from Allied Vision.

## Build

```bash
mkdir build && cd build
cmake ..
make -j$(nproc)
```

## Usage

```bash
./FireWatchTower_2axis [options]

Options:
  -h, --help          Produce help message
  -i, --init [bool]   Run gimbal endstop initialization sequence
  -s, --start [bool]  Auto-start camera acquisition on launch
```

Example:
```bash
./FireWatchTower_2axis --init true --start true
```

## Serial Communication

The host communicates with the Arduino firmware over `/dev/ttyACM0` at 115200 baud.

### Incoming Telemetry

The firmware periodically sends motor status lines prefixed with `$`, semicolon-delimited:
```
$Xenc;Xerr;sgt_val;sgt_stat;is_moving;control_status;hdg;deviation_warn;humid;temp;fan_pwm
```

Parsed into `motor_info` struct in [Serial.h](Serial.h).

### Outgoing Commands

Single-character commands sent via `serial.sendCommand()`:
- `r` — Reset motor parameters and power on
- `e` — Reset SGT (step goal threshold)
- `q` — Run endstop homing sequence
- `y` — Load heading calibration from EEPROM
- `ud80` — Set auto-scan step length
- `p` — Step yaw to next position (trigger after stop)
- `kd<heading>` — Set target heading (guided mode)

## MQTT Integration

Connects to broker at `172.16.42.1` (hardcoded; modify [MQTT.cpp](MQTT.cpp) to change). Subscribes to two control topics and publishes status/camera events.

### Subscribed Topics

| Topic | Payload | Effect |
|-------|---------|--------|
| `GGS/FWT/<name>/ControlCode` | `0` or `1` | Switch control mode: 0=free scan, 1=guided heading |
| `GGS/FWT/<name>/target_HDG` | Float string | Target yaw heading for guided mode |

### Published Topics

| Topic | Payload | Description |
|-------|---------|-------------|
| `GGS/FWT/<name>/StatusCode` | Integer | Current control mode |
| `GGS/FWT/<name>/CamEvent/RGB` | — | Camera event notifications |

## Interactive Commands (stdin)

While running, the host accepts commands on stdin parsed by Boost.Spirit:

| Command | Description |
|---------|-------------|
| `start` | Start camera acquisition |
| `stop` | Stop camera acquisition |
| `set camera <option> <value>` | Set camera parameter via Vimba |
| `set fps <value>` | Change image rate (images/sec) |
| `set motorctl <command>` | Send raw command to firmware |
| `debug` | Toggle motor controller info output |
| `exit` | Shut down |

## Source Files

| File | Purpose |
|------|---------|
| [FWT_host.cpp](FWT_host.cpp) | Main entry point, CLI parsing, main loop |
| [Camera.h](Camera.h) / [Camera.cpp](Camera.cpp) | Vimba camera handler, image queue, JPEG XL encoding |
| [MQTT.h](MQTT.h) / [MQTT.cpp](MQTT.cpp) | Paho MQTT client wrapper, callback handling |
| [Serial.h](Serial.h) | Boost.ASIО serial port, telemetry parser |
| [Parser.h](Parser.h) | Boost.Spirit stdin command parser |
| [timing.h](timing.h) | Timer utility class |
| [Log.h](Log.h) | Logging utilities |
| [JPEG_XL.h](JPEG_XL.h) | JPEG XL encoding wrapper |