Input_rc Module Documentation

Toolbox: Sensors and Actuators

Introduction

One-sentence Description: Acquires and outputs remote controller input signals from the PX4 side, supporting customizable channel selection and various remote controller status information.

This module belongs to the Sensors and Actuators interface library of the RflySim toolchain and is used to obtain raw remote controller input data received by the PX4 flight controller on the Simulink side. Based on user configuration, the module can output PWM pulse width values for specified channels, and optionally output auxiliary information such as the total detected channel count, remote controller failsafe status, input source type, received signal strength indicator (RSSI), and connection loss status, satisfying diverse drone remote control simulation development requirements.

This module relies on the remote controller input parsing results from the PX4 flight controller. In the simulation chain, PX4 parses real remote controller signals or simulation-generated remote control signals and passes them to this module. Users can directly read and utilize the data in custom control algorithms within Simulink, supporting typical scenarios such as hardware-in-the-loop simulation and remote controller controller development and debugging, without requiring additional development of remote controller signal reception and parsing logic.

Port Descriptions

Input Ports (Inputs)

This module has no input ports.

Output Ports (Outputs)

Port Name	Data Type	Dimension	Description
rc_channels	uint16	N×1	N is the number of selected channels; outputs the PWM pulse width values of the corresponding selected remote controller channels
channel_count	uint32	Scalar	Total number of remote controller channels detected by the PX4 detector; activated only when the "Channel Count" output option is enabled
rc_failsafe	boolean	Scalar	Remote controller failsafe flag; true indicates the remote controller transmitter has triggered a FailSafe signal or is out of operational range; activated only when the "RC Failsafe" output option is enabled
rc_input_source	uint8	Scalar	Enumerated value indicating the source of the remote controller input signal; definitions are given in RC_INPUT_SOURCE_ENUM.m; activated only when the "RC Input Source" output option is enabled
rssi	int	Scalar	Received Signal Strength Indicator; range: <0 undefined, 0 no signal, 255 full signal reception; activated only when the "RSSI" output option is enabled
rc_lost	boolean	Scalar	Remote controller connection status flag; true indicates that no valid data frame was received within the expected time, meaning the connection has been lost; activated only when the "RC Lost Connection" output option is enabled

Parameter Configuration (Parameters)

The following parameters can be configured in the Mask dialog box opened by double-clicking the module:

Parameter Name	Type	Default Value	Optional Values/Range	Description
SelectedChannels	vector of uint16	[1,2,3,4]	Each element ranges from 1 to the maximum supported channel count	Remote controller channel numbers to be output
OutputChannelCount	boolean	false	true/false	Whether to output channel count information
OutputRcFailsafe	boolean	false	true/false	Whether to output the remote controller failsafe flag
OutputRcInputSource	boolean	false	true/false	Whether to output the remote controller input source information
OutputRssi	boolean	false	true/false	Whether to output the received signal strength indicator
OutputRcLost	boolean	false	true/false	Whether to output the remote controller connection loss flag
SampleTime	double	0.01	>0	Module sampling time, in seconds

Parameter Setting Descriptions

SelectedChannels

This parameter specifies the remote controller channel numbers to be output. For example, entering [1,2,3,4] indicates outputting the PWM signal values for channels 1–4; the dimension of the output port rc_channels is determined by the number of channels specified by this parameter.

Optional Output Control Parameters

The five parameters OutputChannelCount, OutputRcFailsafe, OutputRcInputSource, OutputRssi, and OutputRcLost control whether the corresponding information is output. When a parameter is enabled, the module adds the corresponding output port to output the specified information.

SampleTime

This parameter specifies the sampling interval for the module to read remote controller data from the simulated flight controller, in seconds. A value of 0.01 generally suffices for most simulation scenarios.

Module Characteristics (Block Characteristics)

Characteristic	Value
Supported Data Types	double, single, uint16, uint32, boolean
Direct Feedthrough	No
Sample Time	Discrete
Code Generation Support	No

Data Communication Protocol

This module does not involve network communication.

Related Modules

Module Name	Description
Output_pwm	Outputs PWM signals to drone actuators
IMU_sim	Simulates inertial measurement unit data output
GPS_sim	Simulates GPS position and velocity data output
Baro_sim	Simulates barometric altimeter data output
Mag_sim	Simulates magnetometer data output

Usage Example

For related usage examples, refer to the following path:

``` [RflySim Installation Path]/RflySimAPIs/5.RflySimFlyCtrl/0.ApiExps/2.PSPOfficialExps/Readme.pdf

Please refer to Readme.pdf in the path above for complete example descriptions and operational steps.

Notes and Common Issues

• Initialization Sequence: This module relies on the PX4底层 communication link initialization in the RflySim simulation environment. It must be placed within an enabled subsystem in the Simulink model, and the remote controller signal should only be read after the flight controller completes its initialization. Otherwise, it may output invalid zero-value data.
• Sample Time Matching: The module’s sample time is recommended to match the flight controller’s state update cycle (typically 0.004 s to 0.01 s). An overly large sample time will cause remote controller command update delays, while an overly small sample time introduces unnecessary performance overhead.
• Failsafe State Judgment: The reliability of the RC Failsafe output depends on the hardware configuration of the remote controller receiver. Some low-cost PPM receivers do not actively report failsafe states; therefore, it is recommended to jointly assess the remote controller link status by combining the RC Lost Connection output, avoiding misjudgment based on a single signal.
• Channel Selection Configuration: The selected channel index must not exceed the maximum number of channels actually detected by PX4. If the configured channel index exceeds the detection range, the corresponding output will remain at the initial zero value. You can enable the Channel Count output to verify the actual number of detected channels.
• RSSI Signal Range Explanation: The RSSI output valid range is 0–255. A value less than 0 indicates that the current remote controller input source does not support RSSI output, which is not a module fault. To use the RSSI function, please confirm that your remote controller input source supports this signal output.
• Consistency Between Simulation and Real Hardware: In HITL simulation, this module reads the remote controller signals connected to the real hardware. If using pure simulation (SITL) mode, you must manually input remote controller channel values via Simulink; otherwise, no valid input will be available by default.

Changelog

• v4.0 (2024-08-12): Initial release, supporting outputs of remote controller channel values, channel count, failsafe status, input source, RSSI, and connection status.