RC_SUB_ACTION Enumeration

RC_SUB_ACTION is an enumeration that defines the operational state of remote control (RC) channel input handling in a drone control system.
It determines how RC commands from a transmitter (TX) are processed and whether they are passed through, modified, or overridden by software.

This enum is used to manage the autonomy level of RC input—ranging from fully released (no input sent) to active joystick control (direct channel override)—and plays a key role in safety and automation logic, especially during mode transitions like switching to guided flight.

Definition

typedef enum RC_SUB_ACTION 
{
    // No RC channel data is sent to the drone.
    RC_SUB_ACTION_RELEASED                      =   0,
    
    // Center values (1500 µs) are sent; physical TX has no effect.
    RC_SUB_ACTION_CENTER_CHANNELS               =   1,
    
    // Last known RC values are frozen and continuously sent.
    RC_SUB_ACTION_FREEZE_CHANNELS               =   2,
    
    // Live RC channel values from software (e.g. app) are sent.
    RC_SUB_ACTION_JOYSTICK_CHANNELS             =   4,
    
    // Velocity commands sent instead of raw RC; used in guided mode.
    RC_SUB_ACTION_JOYSTICK_CHANNELS_GUIDED      =   8
} RC_SUB_ACTION;

Type: enum (C++ scoped enumeration)
Purpose: Controls how RC input is applied to the drone’s flight controller
Used in: ANDRUAV_VEHICLE_INFO::rc_sub_action to reflect current RC override state
Values are powers of two or sequential integers, suggesting possible bitmask use or simple state tracking
Initial value: Set to RC_SUB_ACTION_RELEASED during initialization

The enum is tightly coupled with RC override logic, where physical transmitter input can be disabled in favor of software-generated commands—critical for autonomous or app-controlled flight.

Enum Values

Example Usages

Initialization

One primary use is initializing the RC state when the system starts:

de::fcb::mission::CMissionManager::getInstance().getAndruavMission().clear();

// Initialize RC override state to released (no input sent)
m_andruav_vehicle_info.rc_sub_action = RC_SUB_ACTION::RC_SUB_ACTION_RELEASED;

Command Parsing

Another key usage is in parsing incoming commands from a remote source (e.g. mobile app):

int rc_sub_action = cmd["b"].get<int>();

// Interpret integer command as RC_SUB_ACTION enum
m_fcbMain.adjustRemoteJoystickByMode((RC_SUB_ACTION)rc_sub_action);

Here, the JSON field "b" carries the desired RC mode, which is cast directly into the RC_SUB_ACTION enum and dispatched to control logic.

Guided Mode Activation

The RC_SUB_ACTION_JOYSTICK_CHANNELS_GUIDED mode is activated when the drone enters guided flight and joystick control is desired:

m_andruav_vehicle_info.rc_sub_action =
    RC_SUB_ACTION::RC_SUB_ACTION_JOYSTICK_CHANNELS_GUIDED;

m_fcb_facade.sendErrorMessage(..., std::string("RX Joystick Guided Mode"));

Control Dispatch

In the control dispatch logic, both joystick modes are grouped but behavior diverges based on current flight mode:

case RC_SUB_ACTION::RC_SUB_ACTION_JOYSTICK_CHANNELS:
case RC_SUB_ACTION::RC_SUB_ACTION_JOYSTICK_CHANNELS_GUIDED: {
  if (m_andruav_vehicle_info.flying_mode == VEHICLE_MODE_GUIDED) {
    enableRemoteControlGuided(); // Uses ctrlGuidedVelocityInLocalFrame
  } else {
    enableRemoteControl(); // Uses sendRCChannels()
  }
}

Timeout Handling

In the main control loop, timeout handling is applied for safety:

case RC_SUB_ACTION::RC_SUB_ACTION_JOYSTICK_CHANNELS_GUIDED: {
  if (now - m_andruav_vehicle_info.rc_command_last_update_time > RCCHANNEL_OVERRIDES_TIMEOUT) {
    releaseRemoteControl();
  }
}

This ensures safety: if no new joystick input arrives within RCCHANNEL_OVERRIDES_TIMEOUT (3 seconds), control is released and the drone may enter a safe mode (e.g., brake).

Notes

RC_SUB_ACTION_JOYSTICK_CHANNELS_GUIDED is specifically intended for guided mode flight, where velocity commands (not raw PWM) are sent—this enables smoother autonomous maneuvers.
The enum values skip 3 and 5–7, suggesting possible future extensions or alignment with bitmask-style flags (though not currently used as bitflags).
Despite being called “joystick”, this system does not require a physical joystick—it refers to software-emulated RC inputs from apps or tracking systems.
The system may automatically switch to RC_SUB_ACTION_JOYSTICK_CHANNELS_GUIDED from RC_SUB_ACTION_JOYSTICK_CHANNELS when entering guided flight.