This is an instance of the Beta 1.2 version of dRehmFlight FC available here
This is a work in progress and is not ready yet. The flight controller is being transformed for an F-35 version of an r/c vertical take-off and landing model aircraft, as described by Nicholas Rehm, using a Teensy 4.1 and IMU 6050.
The following has been added to Nicholas Rehm code:
A C++ Config class (in folder src/Config) that supplies the following:
- EEPROM parameters save and retrieval
- USB port menu to allow for parameters modification at boot time
Some of the steps remaining to be done:
- Code adaptation for targeted model aircraft configuration
- Add Angle/Angle2/Rate selection
- Add USB trace output control
- Testing tools for Motors
- Testing tools for Servos
- Overall verification with selected electronics and hardware
- Data Logging for post-flight analysis
- Tests in flight
- Assess adding USB menu access in the main loop()
- Support for TelemetryViewer
Other potential changes:
- Telemetry transfer through S-Port
- Config modification from control transmitter
- LCD for debugging support
- Port to a standard quad FC (if fast enough)
- Other devices integration
Licensing: GPL-3.0
At boot time the setup() function of the main program is called to initialize the Teensy for preparation of the main loop() function. After the Serial port is initialized, the config.setup() method is called. This method retrieves the current configuration from the EEPROM and adjusts all parameters of the main application. If the EEPROM doesn't contain valid information (a crc32 checksum and a version number are used to ensure that), the parameters are initialized with the default values as defined in the original main application content.
The config.setup() method will then wait for 10 seconds for the user to send a carriage return character to the Teensy. If so, it will then show the main menu giving access to all configuration parameters of the main application and several other management functions. If nothing is received within 10 seconds, the config.setup() function will exit and control will be returned to the main application setup function that will resume the preparation of the device.
As stated, the Config class supplies a facility to modify any parameters of the main application through a series of menus. Menu entries are of the following kinds:
- Parameter: The current parameter name is shown in squared brackets, the value is in parentheses and can be modified if selected.
- Menu: If selected, the entry will show a sub-level menu.
- Task: A simple task will be launched if selected.
- Exit: Return to the main application.
The interaction with the menus is as follow:
- A menu is presented on the screen with a title and a list of numbered entries.
- A
>character is presented in the next line. - The user enters a number corresponding to the menu entry for which he wants to interact with, followed by a carriage-return. If no number is entered or the escape character is sent, the preceding menu will be shown to the user. If the current menu is the Main Menu, it will be refreshed.
- If the selected entry corresponds to another menu, it will then be presented to the user.
- If the selected entry corresponds to a modifiable parameter, the user will be requested to enter a new value for the parameter followed by a carriage-return. If no value is entered or the escape character is sent, the parameter will be left unchanged. For choice selectable parameters, a list of choices is presented and the corresponding choice number must be entered.
- If the selected entry corresponds to an action to be executed, it will be done and a message indicating the result of the action will be shown on screen.
To exit the main menu, it is required to explicitly enter the Exit menu entry number.
Any change made to a parameter is immediately modified in the running application. It is NOT updated in the saved parameters in EEPROM, this to allow for testing when the end state may not be stable or when there are other parameters to update. The user must explicitly request the main menu entry Save Params to EEPROM to have all parameters be saved in EEPROM.
The debugging menu is used to set debug support variables in the application. These variables are not saved in EEPROM and, if changed, will retrieve their default value at boot time.
Once control is returned to the main application, the config class is not allowed to regain control unless the Teensy is reset. This is to limit interfering with the main loop() function once it has been started. The impact: parameter changes that have not been saved before leaving control to the main application will not be retained. This behavior will be revisited once the impact of adding access to the parameters menu from the main loop() function is tested and conclusive.
The following changes have been made so far to the main source code src/dRehmFlight_Tensy_BETA_1.2.ino. This will be updated as changes are being done.
- New User parameter:
USB_output,receiver_onlyfor debugging purposes. Their value is modifiable through the menu system. - In the
setup()function, call to theconfig.setup()method. Before thesetup()function, an#includestatement to get the Config class available. - in the
loop()function, a switch statement to select which debugging output to send to the USB port. - Only 3 motors are being used, Motors 4..6 have been commented out. The 3 used motor are associated with Pins 0, 1, 2. Namely: Front motor, Right Aileron motor, Left Aileron motor respectively
- Only 5 servos are being used, Servos 6..7 have been commented out. The 5 used servos are associated with Pins 6, 7, 8, 9, 10. Namely: Front motor tilt, Right Aileron, Left Aileron, Right Elevator, Left Elevator.
- Channel numbers are separated from their PWM values: name of channel_x_pwm variables changed to relate them to their functions: channel_1_pwm is now throttle_pwm, channel_2_pwm is now aileron_pwm, and also for elevator, rudder, throttle_cut, and aux1. The same is done for the channel_x_pwm_prev variables. In the user-specific parameters, new parameters are used to associate channels with their functions. Current default values reflect the original code. This is to simplify the user preference changes for channel associations and the eventual integration in the menu parameters (and EEPROM saving).
- Motors and servos are separated from their pin values. No more s1, s2, ... and m1, m2...
- Code cleanup to get rid of compilation warning messages.
- FailedSafe() modified to take care of the sbusFailSave value when SBUS is being used.
- Debugging output is now using Serial.printf to format numbers such that they will have enough room without changing line length. Easier to look at the values while the display is scrolling.
- All numerical values used on the controlMixer() function are adjustable through the configuration menus.
- Transmitter: FrSky Taranis X9D
- Receiver: R-XSR (SBus)
- ESC: (Oneshot125)
- 3 Motors XNOVA Lightning 2206
- 5 PWM Servos
Here are the specific Transmitter command values that are used in the main code. These are related to the way the transmitter has been programmed.
- Throttle Cut (channel 7): Value lower than 1600 on channel. Engines are armed when the value is greater or equal to 1600.
- Hover, Transition, Forward Flight modes (channel 8): Greater than 1600 is Hover, Between 1400 and 1600 is transition, lower than 1400 is Forward Flight.
The 3D Parts contains all the parts that have been designed in support of this effort. Namely:
- Ailerons and their motor holder (FreeCAD+STEP+STL)
- Front motor holder (FreeCAD+STEP+STL)
- Servo holders (Fusion360+STEP+STL)