Embedded Gateway for Drone Flight Control
CM4 based gateway enabling zero installation remote flight control from any PC browser, with full integration for external automation and AI flight software.
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System at a glance
One Gateway. From PC to Drone.
Remote PC
Operator or external software
UDP Link
WebRTC DataChannel
CM4 gateway
Control logic and monitoring
Signal interposer
ADC measurements, switching, DAC outputs
Controller → drone
RF transmission to the aircraft
Compatibility
Compatibility & Enclosure
DJI Aircraft Compatibility
Supports all DJI drones compatible with RC-N1, RC-N2 and RC-N3 controllers.
Integrated Controller Enclosure
Designed for the DJI RC-N1, RC-N2 and RC-N3, replacing the phone mount area with the Haddacerra gateway.
Controllers with built-in screens are not supported by the current enclosure design.
System Specifications
Physical hardware components, compute architecture, and radio interface specifications.
| Subsystem | Hardware Specification | Design Function & Parameter |
|---|---|---|
| Compute Module | Raspberry Pi Compute Module 4 | Handles local telemetry processing, input decoding, and UDP network tunnel execution. |
| System Storage | On-board eMMC Flash Memory | eMMC storage eliminates reliance on removable microSD media. |
| Interposer | Custom PI-zero sized PCB | Daughter card featuring switches, DAC's, closed loop voltage sensing with ADC's, watchdog protection and TVS ESD protection. |
| CM4 Carrier Board | Custom CM4 IO Board | Houses the CM4 compute module and Interposer PCB. Integrates onboard power regulation circuitry and a 2000mAh battery. |
| WiFi Interface | Skylab WG217 Wi-Fi Module | The WG217 module uses Realtek RTL8811CU and operates on 5 GHz while configured to a 20 MHz channel bandwidth, intended to limit the occupied spectrum. actual range, stability and noise may vary. |
Interposer Architecture
Hardware-level integration and signal flow between transmitter electronics, companion compute, and network layers.
Analog & Digital Stick Intercept
The interposer sits inline between the RC's joystick signal circuitry and its main board, interfacing with five control channels without modifying the controller's firmware. It monitors the original signals and preserves their native path in NC (Passthrough Mode). When NO (CM4/Remote Control Mode) is selected, hardware analog switches route the DAC's signals into the transmitter path, allowing the CM4 to supply remote or AI generated control inputs.
UDP Transport / NAT Traversal
The gateway establishes low latency control sessions through WebSocket based signaling coordinated between the browser, the CM4 agent, and the relay infrastructure. ICE (Interactive Connectivity Establishment) evaluates available network paths, leveraging STUN for public address discovery and a Coturn relay as a mandatory fallback when direct peer-to-peer connectivity is blocked by strict firewalls or CGNAT. Control data and telemetry travel over a fully encrypted WebRTC DataChannel secured via DTLS and SCTP over UDP. This architecture enables reliable, secure remote hardware operation across cellular networks and strict CGNAT without requiring a publicly reachable IP address or VPN.
Hardware State Switching
High speed switches determine which control signals reach the RC transmitter. In NO(CM4) mode, the DAC outputs drive the RC control lines, enabling remote or AI inputs. In NC(Passthrough) mode, the DAC outputs are isolated from the RC control lines, allowing the RC's original signals to pass through normally. The gateway continues monitoring signal levels and system state.
Multi-Layer Safety & Failsafe Architecture
DUAL-LAYER PROTECTION- • UDP Telemetry Health: Continuous software monitoring evaluates packet arrival rates, jitter, and frame loss across the IP tunnel.
- • Connection Timeout Limits: If remote PC telemetry drops or exceeds preset latency thresholds, the software immediately executes defined safe fallback routines.
- • Command Boundary Validation: Incoming remote control arrays are checked against valid operational bounds to prevent malformed or out-of-range inputs from executing.
- • Hardware-Level Manual Takeover: The local pilot can restore manual control(NC Mode) through the state toggle on the left side of the enclosure.
- • Hardware Relay Behavior: Dedicated hardware switching completely isolates the CM4 companion compute board when manual control is engaged or triggered.
- • Hardware Watchdog IC: Monitors CM4 GPIO heartbeat pulses; triggers instant physical switchover to manual controls and an audible alarm if companion compute fails or freezes.
- • Multi-Channel ESD Protection: Dedicated TVS diode arrays on all exposed signal lines safeguard onboard logic and companion compute against high voltage transient spikes.
- • Closed Loop Hardware Telemetry: 12 ADC channels monitor five passthrough (NC) signal channels, five driven (NO) signal channels, the physical state switch, and the main 5 V power rail. This provides real-time monitoring of signal levels, switching state and power rail health.
Interactive calibration wizard normalizes incoming USB HID inputs across 5 control channels (AETR + Gimbal Tilt). Maps raw stick deflection to a normalized range (-1.00 to +1.00) with real-time visual UI telemetry verification prior to link arming.
Closed loop voltage sampling reads center voltages directly from host transmitter channels. Trims DAC output levels to match host hardware baselines and commits calibration vectors directly to onboard DAC EEPROM. Eliminates DC voltage steps upon switchover and removes host RC recalibration requirements.
Technical Questions & Answers
Common deployment queries
Can I control a DJI drone remotely over the internet from a PC or laptop?
Yes. The Haddacerra CM4 interposer bridges physical controller inputs (such as DJI RC-N1/N2/N3 or EdgeTX radios) to a WebRTC gateway. This allows a remote pilot to operate the drone directly from any PC or laptop browser over 4G/5G mobile networks using encrypted, P2P data channels engineered for strict CGNAT traversal.
How to control a DJI drone from a PC or laptop?
Power on the Haddacerra CM4 gateway and physical controller (such as a DJI RC-N1/N2/N3 or EdgeTX), set the gateway state to NO mode(CM4), and open the web UI on any PC or laptop with a USB controller connected. The WebRTC gateway streams real-time telemetry and control inputs over 4G/5G mobile networks across CGNAT.
Can I fly a DJI drone with a USB PC gamepad or joystick?
Yes. The Haddacerra web UI uses the browser's native Gamepad API to map standard USB gamepads (such as Xbox, PlayStation), or EdgeTX radios directly inside any PC browser. Control inputs are sent over low latency WebRTC channels to the CM4 gateway, which drives the physical DJI remote controller signals via onboard DACs.
Is there a DJI Fly app alternative for PC or laptop?
DJI does not offer an official desktop version of DJI Fly. Haddacerra enables remote control of compatible DJI drones from a PC browser, with the original DJI controller remaining at the drone's location and maintaining its normal radio link. No modified app or DJI Mobile SDK integration is required. DJI Fly app or other compatible apps can be used normally.
Can I control a drone over a 4G or 5G cellular network?
Yes. The Haddacerra CM4 gateway establishes low latency and secure WebRTC data channels engineered to operate seamlessly over standard 4G or 5G cellular connections. Because mobile networks enforce strict Carrier-Grade NAT (CGNAT), the system uses integrated STUN/TURN traversal to maintain direct, secure peer-to-peer control and live telemetry streams without requiring a static IP or VPN tunnel.
How is live video transport handled?
The gateway handles flight control inputs and telemetry separately from video. Live video is streamed from the mounted Android device via RTSP to a MediaMTX server, making the feed available in the web control portal or a browser. The live stream uses the mobile device's internet connection, while the gateway's UDP tunnel handles control and telemetry.
What radio controllers are supported?
The system is designed to fit around the RC-N1 RC-N2 RC-N3, but can also support open-source radio platforms running EdgeTX.
Does Haddacerra include an AI flight control system?
No. Haddacerra provides the hardware platform for remote, automated or AI generated control inputs. The AI or automation software runs externally and supplies the control commands; The gateway handles their delivery to the compatible radio controller, along with signal interfacing, monitoring and hardware mode switching.