627 Delta Wing Flight Control Mixer with PWM Output
627 : Delta Wing Flight Control Mixer with PWM Output
- Author: Markus Jsaper Lassen
- Description: Digital flight control system for a delta wing aircraft that processes control inputs, applies stabilization logic, and generates PWM signals for elevon and rudder actuators using a time-multiplexed output interface.
- GitHub repository
- Open in 3D viewer
- Clock: 50000000 Hz
How it works
This project implements a digital flight control mixer for a delta wing aircraft using a limited 8-bit IO interface.
Control and sensor data are received through the 8-bit input bus (ui_in) using a simple command-based protocol. Data is first sent as a command word to select a target register, followed by a data word to update that register. These registers represent control inputs and internal system states.
The system processes these inputs using digital logic to generate actuator control signals for the left elevon, right elevon, and rudder. The control signals are converted into PWM-compatible values representing actuator positions.
Due to the limited number of output pins, the three actuator signals are time-multiplexed onto a single 8-bit output bus (uo_out). Each output cycle contains:
- 3-bit channel tag identifying the actuator (left elevon, right elevon, or rudder)
- 5-bit PWM value representing the actuator command
This allows multiple control channels to be transmitted efficiently over a constrained interface.
How to test
-
Provide an 8-bit input word on
ui[7:0]. -
Send a command word of the form:
0xFFin the upper 8 bits- register ID in the lower 8 bits
-
Follow with a data word containing the value to be written to that register.
-
Observe the output on
uo[7:0]. The output cycles through actuator channels and provides:- Upper 3 bits: actuator identifier
- Lower 5 bits: PWM value
-
Decode the output stream to extract individual actuator commands:
001→ left elevon010→ right elevon011→ rudder
External hardware
This design is fully digital and does not require external hardware to operate.
For practical use, the output can be connected to:
- A microcontroller or FPGA to decode the multiplexed PWM data
- Servo drivers or PWM generators to control physical actuators
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | Data input bit 0 (LSB) | PWM data bit 0 | Unused |
| 1 | Data input bit 1 | PWM data bit 1 | Unused |
| 2 | Data input bit 2 | PWM data bit 2 | Unused |
| 3 | Data input bit 3 | PWM data bit 3 | Unused |
| 4 | Data input bit 4 | PWM data bit 4 | Unused |
| 5 | Data input bit 5 | Channel tag bit 0 | Unused |
| 6 | Data input bit 6 | Channel tag bit 1 | Unused |
| 7 | Data input bit 7 (MSB) | Channel tag bit 2 | Unused |