Continious Rotation Servo Control with Potentiometer


Ok I am working on something pretty hacky and I was looking for some advice ;D. First of my coding is not the best so I’d be grateful for some advice.

Let me explain. I have a .net gadgeteer spider connected via an extender to a servo that has been hacked. The servo speed is being controlled by pwm but because it is hacked for continuous rotation I have removed the stop from the potentiometer and connected it so I can control the position.

All is well - I get the position of the servo from the pot and can control speed and stop the servo.

When working together though to control position it goes back and forward a lot before it stops and is quite slow to respond.

Problems seem to be noise from the servo that causes the potentiometer value to spike and change a lot. I have it on a separate supply with common ground and am trying capacitors but not luck. I also tried smoothing it with a running average but it slows it down too much.

This is the main bit of my code and I wondered if anyone had any suggestion for how to control the position and movement to a new position based on moving the servo and stopping when it reaches the desired position.

Any advice much appreciated.

   void compass_MeasurementComplete(Compass sender, Compass.MeasurementCompleteEventArgs e)
            Debug.Print("Compass" + e.Angle);

        void timer_Tick(GT.Timer timer)

        int lastPosition;
        int movingToPosition; // constantly updated
        bool movingForward = false;

        // move servo to a particular position
        void move(int moveToPosition)
            // return current pot position
            int currentPosition = potDegrees();
            Debug.Print("current position: " + currentPosition);

                        // stop with definable threshold value
            if (currentPosition > (moveToPosition - stopThreshold) && currentPosition < (moveToPosition + stopThreshold))
           //     moveServo(stopSpeed);
                servo.IsActive = false;
                servo.IsActive = true;
                // first work out direction to move in
                // forward
                if (currentPosition < moveToPosition)
                // backwards
                else if (moveToPosition < currentPosition)

        // reads the potentiometer and converts this to degrees of rotation
        int potDegrees()
            // read pot value
            double currentValue = pot.ReadProportion();

            // map to 360 degrees
            double degreeValue = map(currentValue, 0, 1, 0, 360);

            // smooth spikes
    //        int finalValue = smooth((int)degreeValue);
            int finalValue = ((int)degreeValue);
            // convert to int and return
            return (finalValue);