F/A-18 StandBy Compass

[Rapti]

Hello everyone,
I am trying to build the Standby Compass for my F/A-18 pit.
For the A-10 I have successfully put it into operation with an Arduino sketch available on github:

#define DCSBIOS_IRQ_SERIAL

#include <AccelStepper.h>
#include "DcsBios.h"

struct StepperConfig {
  unsigned int maxSteps;
  unsigned int acceleration;
  unsigned int maxSpeed;
};

class Vid60Stepper : public DcsBios::Int16Buffer {
  private:
    AccelStepper& stepper;
    StepperConfig& stepperConfig;
    inline bool zeroDetected() {
       return digitalRead(irDetectorPin) == 1;
       }
    unsigned int (*map_function)(unsigned int);
    unsigned char initState;
    long currentStepperPosition;
    long lastAccelStepperPosition;
    unsigned char irDetectorPin;
    long zeroOffset;
    bool movingForward;
    bool lastZeroDetectState;

    long normalizeStepperPosition(long pos) {
      if (pos < 0) return pos + stepperConfig.maxSteps;
      if (pos >= stepperConfig.maxSteps) return pos - stepperConfig.maxSteps;
      return pos;
    }

    void updateCurrentStepperPosition() {
      // adjust currentStepperPosition to include the distance our stepper motor
      // was moved since we last updated it
      long movementSinceLastUpdate = stepper.currentPosition() - lastAccelStepperPosition;
      currentStepperPosition = normalizeStepperPosition(currentStepperPosition + movementSinceLastUpdate);
      lastAccelStepperPosition = stepper.currentPosition();
    }
  public:
    Vid60Stepper(unsigned int address,
        AccelStepper& stepper,
        StepperConfig& stepperConfig,
        unsigned char irDetectorPin,
        long zeroOffset, unsigned int (*map_function)(unsigned int)): Int16Buffer(address),
     stepper(stepper),
     stepperConfig(stepperConfig),
     irDetectorPin(irDetectorPin),
     zeroOffset(zeroOffset),
     map_function(map_function),
     initState(0),
     currentStepperPosition(0),
     lastAccelStepperPosition(0)
    {
    }

    virtual void loop() {
      
      if (initState == 0) { // not initialized yet
        pinMode(irDetectorPin, INPUT);
        stepper.setMaxSpeed(stepperConfig.maxSpeed);
        stepper.setSpeed(1200);
        
        initState = 1;
      }
      if (initState == 1) {
        // move off zero if already there so we always get movement on reset
        // (to verify that the stepper is working)
        if (zeroDetected()) {
          stepper.runSpeed();
        } else {
            initState = 2;
        }
      }
      if (initState == 2) { // zeroing
        if (!zeroDetected()) {
          stepper.runSpeed();
        } else {
            stepper.setAcceleration(stepperConfig.acceleration);
            stepper.runToNewPosition(stepper.currentPosition() + zeroOffset);
            // tell the AccelStepper library that we are at position zero
            stepper.setCurrentPosition(0);
            lastAccelStepperPosition = 0;
            // set stepper acceleration in steps per second per second
            // (default is zero)
            stepper.setAcceleration(stepperConfig.acceleration);
            
            lastZeroDetectState = true;
            initState = 3;
        }
      }
      if (initState == 3) { // running normally
        
        // recalibrate when passing through zero position
        bool currentZeroDetectState = zeroDetected();
        if (!lastZeroDetectState && currentZeroDetectState && movingForward) {
          // we have moved from left to right into the 'zero detect window'
          // and are now at position 0
          lastAccelStepperPosition = stepper.currentPosition();
          currentStepperPosition = normalizeStepperPosition(zeroOffset);
        } else if (lastZeroDetectState && !currentZeroDetectState && !movingForward) {
          // we have moved from right to left out of the 'zero detect window'
          // and are now at position (maxSteps-1)
          lastAccelStepperPosition = stepper.currentPosition();
          currentStepperPosition = normalizeStepperPosition(stepperConfig.maxSteps + zeroOffset);
        }
        lastZeroDetectState = currentZeroDetectState;
        
        
        if (hasUpdatedData()) {
            // convert data from DCS to a target position expressed as a number of steps
            long targetPosition = (long)map_function(getData());

            updateCurrentStepperPosition();
            
            long delta = targetPosition - currentStepperPosition;
            
            // if we would move more than 180 degree counterclockwise, move clockwise instead
            if (delta < -((long)(stepperConfig.maxSteps/2))) delta += stepperConfig.maxSteps;
            // if we would move more than 180 degree clockwise, move counterclockwise instead
            if (delta > (stepperConfig.maxSteps/2)) delta -= (long)stepperConfig.maxSteps;

            movingForward = (delta >= 0);
            
            // tell AccelStepper to move relative to the current position
            stepper.move(delta);
            
        }
        stepper.run();
      }
    }
};

/* modify below this line */

/* define stepper parameters
   multiple Vid60Stepper instances can share the same StepperConfig object */
struct StepperConfig stepperConfig = {
  6000,  // maxSteps
  2000, // maxSpeed
  1000 // acceleration
  };


// define AccelStepper instance
AccelStepper stepper(AccelStepper::DRIVER, 5, 6);
// define Vid60Stepper class that uses the AccelStepper instance defined in the line above
//           v-- arbitrary name
Vid60Stepper hsiHdg(0x104c,          // address of stepper data
                             stepper,         // name of AccelStepper instance
                             stepperConfig,   // StepperConfig struct instance
                             4,              // IR Detector Pin (must be HIGH in zero position)
                             0,               // zero offset
                             [](unsigned int newValue) -> unsigned int {
  /* this function needs to map newValue to the correct number of steps */
  return map(newValue, 0, 65535, 0, stepperConfig.maxSteps-1);
});


void setup() {
  DcsBios::setup();
  
}

void loop() {
 
  DcsBios::loop();
}

This uses the “heading” value of the HSI as input for the standby compass: hsiHdg(0x104c).

However, the F/A-18 does not have an HSI for which the heading value can be used.
However, there is the “Magnetic Heading” under CommonData, which is output for each aircraft.

But I don't know what to enter in the Arduino code.
I tried it with the following value: HdgDegMag(0x0464)
But it does not work.

Does anyone know what needs to be entered?null

 

A-10 Heading:

Common Data Heading:

Edited March 30 by Rapti

[No1sonuk]

One problem you'll have is that the full rotation of the A-10 HSI is 0-65535, but the common data magnetic is 0-359. 

It looks like the code you have is designed to work with 0-65535 input.  Try changing the value shown below.

If that fails, try writing a stepper routine that takes a position number, and send it from a normal DCS-BIOS code block.

[Rapti]

I try that. Thanks for the tip.

Gesendet von meinem SM-S928B mit Tapatalk

[Rapti]

Unfortunately, changing the value did not help.

If anyone has a working sketch, I would be happy, as I unfortunately have no programming skills myself

[No1sonuk]

8 hours ago, Rapti said:

Unfortunately, changing the value did not help.

If anyone has a working sketch, I would be happy, as I unfortunately have no programming skills myself

What's your hardware setup?

[Rapti]

On 4/7/2025 at 7:27 PM, No1sonuk said:

What's your hardware setup?

the stepper motor is an x27-168
The driver is a SparkFun EasyDriver

Its controlled by a arduino nano

Its the same setup then the setup from the warthog project.