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• Jewel Box Calibration

  W4KRL • 04/30/2014 at 22:48 • 0 comments

  Good accuracy and linearity.

• Electrical Schematic

  W4KRL • 04/28/2014 at 14:35 • 0 comments

• Digispark Code

  W4KRL • 04/28/2014 at 14:32 • 0 comments

  // DS_ServoMeter

  // Karl Berger W4KRL

  // April 27, 2014

  // Released into the public domain

  // Converts a 0 to 5 Volt signal into a corresponding

  // position on a servo. The servo command is smoothed to

  // reduce jitter.

  // Uses SimpleServo in the DigiSpark library by

  // Benjamin Holt

  #include <SimpleServo.h>

  //create a servo object

  SimpleServo myservo;

  // The analog input signal is connected to P2

  // For pin mapping see:

  // http://digistump.com/wiki/digispark/tutorials/pinguide

  const int kAnalogInputPin = 1;

  // connect the servo signal line to P5

  const int kServoPin = 5;

  // Most servos are rated for 180 degree span but may be non-linear near

  // the extremes. A meter span of 120 degrees or less is more reliable.

  const int kScaleSpan = 120;

  // 4 samples provides good smoothing. More will slow the response.

  // Less will increase jitter.

  const int kSmoothingSamples = 4;

  //int smoothed_val = 0;

  // attach the servo to a pin then exercise it

  void setup(){

  myservo.attach(kServoPin);

  ExerciseServos();

  }

  // read the analog signal, smooth it and convert it to a position

  // in degrees for display by the servo

  void loop(){

  // static variables retain their value between function calls

  static int smoothed_val = 0;

  // read the input voltage

  int val = analogRead(kAnalogInputPin); // this is pin P2

  // smooth the value by keeping a moving average

  smoothed_val = smoothed_val + ((val - smoothed_val) / kSmoothingSamples);

  // rescale val to the meter span

  val = map(smoothed_val, 0, 1023, 0, kScaleSpan);

  //command the servo to the corresponding position

  SetServo(val);

  //add some delay to let the servo seek its position

  delay(15);

  }

  //adjust the motion of the servo to match the actual

  //position to the command

  void SetServo(int val)

  {

  const int kServoZero = 20;

  const int kServoFullScale = 150;

  int pos = map(val, 0, kScaleSpan, kServoZero, kServoFullScale);

  myservo.write(pos);

  }

  //Position at zero and full scale to check calibration

  void ExerciseServos(){

  const int kDwell = 1000;

  SetServo(0);

  delay(kDwell);

  SetServo(kScaleSpan);

  delay(kDwell);

  SetServo(0);

  delay(kDwell);

  }

• Expanded some build steps

  W4KRL • 04/28/2014 at 13:42 • 0 comments

  Added some detail to the construction and adjustment steps.

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