CConfigFile Configuration System Documentation

Overview

CConfigFile is a singleton pattern implementation that manages JSON-based configuration for the DroneEngage MAVLink module. It provides centralized configuration management with file monitoring, dynamic updates, and backup capabilities.

Class Architecture

Singleton Pattern

• Location: src/de_common/de_databus/configFile.hpp and configFile.cpp

• Pattern: Scott Meyers singleton using static local instance

• Thread Safety: C++11 guarantees thread-safe initialization

• Access Method: CConfigFile::getInstance()

Core Methods

Configuration Loading

• initConfigFile(const char* fileURL) - Initial configuration loading

• reloadFile() - Reload configuration from disk

• GetConfigJSON() - Get reference to parsed JSON object

File Monitoring

• fileUpdated() - Check if configuration file has been modified

• Monitors both file timestamps and programmatic updates

Dynamic Updates

• updateJSON(const std::string& jsonString) - Update configuration at runtime

• Supports nested key notation (e.g., “follow_me.quad.PID_P_X”)

• saveConfigFile() - Persist changes with automatic backup

Configuration Values Read by System

1. Main System Configuration (main.cpp)

Logger Settings

{
    "logger_enabled": true,      // Enable/disable logging system
    "logger_debug": false        // Enable debug logging
}

Event Channels

{
    "event_fire_channel": 16,     // Channel for firing events
    "event_wait_channel": 15      // Channel for waiting events
}

MAVLink Optimization

{
    "default_optimization_level": 2,  // Default message optimization level
    "udp_proxy_enabled": true          // Enable UDP telemetry proxy
}

MAVLink IDs

{
    "mavlink_ids": {
        "de_mavlink_gcs_id": 255,           // GCS system ID
        "only_allow_ardupilot_compid": 0,   // Component ID filter
        "only_allow_ardupilot_sysid": 0     // System ID filter
    }
}

Message Timeouts

Complex nested structure defining timeout intervals for different MAVLink message IDs:

{
    "message_timeouts": {
        "0": [0, 1000, 2000, 3000],      // HEARTBEAT timeouts
        "1": [0, 250, 800, 1000],        // SYS_STATUS timeouts
        // ... many more message ID configurations
    }
}

2. FCB Main Configuration (fcb_main.cpp)

RC Channel Configuration

{
    "rc_block_channel": -1,              // Channel to block (-1 = disabled)
    "rc_channels": {
        "rc_channel_enabled": [1, 1, 1, ...],     // 18 channel enable flags
        "rc_channel_reverse": [1, 1, 1, ...],     // 18 channel reverse flags  
        "rc_channel_limits_max": [2000, 2000, ...], // 18 channel max values
        "rc_channel_limits_min": [1000, 1000, ...], // 18 channel min values
        "rc_smart_channels": {
            "active": true,                           // Enable smart channels
            "rc_channel_enabled": [1, 1, 1, 1],      // Smart channel enables
            "rc_channel_limits_max": [2000, 2000, 2000, 2000],
            "rc_channel_limits_min": [1000, 1000, 1000, 1000]
        }
    }
}

Safety Mode

{
    "read_only_mode": false            // Enable read-only safety mode
}

3. Tracking Configuration

Quadcopter Follow-Me (fcb_tracker_logic_quad.cpp)

{
    "follow_me": {
        "quad": {
            "PID_P_X": 0.2,              // Proportional gain X-axis
            "PID_P_Y": 3.6,              // Proportional gain Y-axis  
            "PID_I_X": 0.0,              // Integral gain X-axis
            "PID_I_Y": 0.0,              // Integral gain Y-axis
            "PID_D_X": 0.01,             // Derivative gain X-axis
            "PID_D_Y": 0.05,             // Derivative gain Y-axis
            "expo_x": 0.0,               // X-axis exponential curve
            "expo_y": 0.0,               // Y-axis exponential curve
            "deadband_x": 0.001,         // X-axis deadband
            "deadband_y": 0.025,         // Y-axis deadband
            "center_hold_enabled": false,    // Enable center hold
            "center_hold_y_band": 0.05,     // Center hold Y-band
            "center_hold_decay": 0.1,       // Center hold decay rate
            "kalman_enabled": true,         // Enable Kalman filter
            "kalman_measurement_noise_r": 0.1, // Measurement noise
            "kalman_process_noise_q": 0.05,   // Process noise
            "rate_limit": 0.05,               // Rate limiting
            "loose_altitude": false            // Loose altitude mode
        }
    }
}

Plane Follow-Me (fcb_tracker_logic_plan.cpp)

{
    "follow_me": {
        "plane": {
            "PID_P_X": 0.8,              // Proportional gain X-axis
            "PID_P_Y": 0.6,              // Proportional gain Y-axis
            "PID_I_X": 0.0,              // Integral gain X-axis  
            "PID_I_Y": 0.1,              // Integral gain Y-axis
            "PID_D_X": 0.1,              // Derivative gain X-axis
            "PID_D_Y": 0.5,              // Derivative gain Y-axis
            // ... similar control parameters as quad
        }
    }
}

4. Network Configuration

{
    "fcb_connection_uri": {
        "ip": "0.0.0.0",              // FCB connection IP
        "port": 7660,                 // FCB connection port
        "type": "tcp"                 // Connection type
    },
    "s2s_udp_listening_ip": "127.0.0.1",     // UDP listening IP
    "s2s_udp_listening_port": "61003",       // UDP listening port
    "s2s_udp_packet_size": "8192",           // UDP packet size
    "s2s_udp_target_ip": "127.0.0.1",        // UDP target IP
    "s2s_udp_target_port": "60000"           // UDP target port
}

5. Module Identification

{
    "module_id": "FCB_CTRL"          // Module identifier
}

Usage Patterns in Code

Standard Access Pattern

de::CConfigFile &cConfigFile = CConfigFile::getInstance();
const Json_de &jsonConfig = cConfigFile.GetConfigJSON();

if (jsonConfig.contains("parameter_name")) {
    auto value = jsonConfig["parameter_name"].get<type>();
}

File Update Monitoring

const bool updated = cConfigFile.fileUpdated();
if (updated) {
    cConfigFile.reloadFile();
    // Re-read configuration values
}

Dynamic Configuration Updates

// Runtime configuration update via message parser
cConfigFile.updateJSON(config.dump());

File Management Features

Automatic Backup

• Creates timestamped backups before saving: filename.bak_YYYYMMDD_HHMMSS

• Preserves configuration history

File Monitoring

• Checks file modification timestamps

• Supports both file-based and programmatic updates

• Thread-safe update detection

Error Handling

• Graceful handling of missing configuration files

• Default value fallbacks for critical parameters

• Comprehensive error logging with colored console output

Configuration File Locations

Primary Configuration

• Main: de_mavlink.config.module.json

Integration Points

Message Parser Integration

The configuration system integrates with the message parser (de_message_parser_base.cpp) to allow remote configuration updates via MAVLink messages.

Cross-Module Usage

• FCB Main: Primary consumer of RC and system configuration

• Tracking Modules: Consume follow-me PID parameters

• Logger System: Uses logger configuration

• Mission Manager: Uses event channel configuration

Best Practices

1. Always check existence of configuration keys before access

2. Use appropriate type casting with .get<type>()

3. Handle missing configurations with sensible defaults

4. Monitor file updates in long-running processes

5. Use nested key notation for dynamic updates to complex structures

Thread Safety

• Singleton initialization is thread-safe (C++11 guarantee)

• File operations use filesystem-level synchronization

• Update operations set pending flags for atomic detection

This configuration system provides a robust, flexible foundation for managing the complex parameter space required by the DroneEngage MAVLink module.