Reads strain gauge load cell with HX711 and controls large pointer.

StrainMeterDemo.ino

#include <HX711.h>
#include <Servo.h> 

#define DOUT 3
#define CLK 2
#define SERVOPIN 9

const int nAvg=5;
const int nXPixels=160;
const int nYPixels=128;

#define maxservo 125 // Maximum degree setting that is safe for servo
#define minservo 45 // Minimum degree setting that is safe for servo

HX711 loadCell(DOUT, CLK);
Servo pointerServo;

float relative_position;
int absolute_position;
int initial_reading;
int servo_range;

void setup() {
  // Setup the LCD
  Serial.begin(115200);

  // Initialize Servo and set to far left
  pointerServo.attach(SERVOPIN);
  move_servo(pointerServo, 0);
  loadCell.set_gain(128);
  // Set all values in history array to 100 point average
  initial_reading = loadCell.read_average(50);
  //initial_reading = abs(initial_reading);

}

void loop() {
  int reading = loadCell.read_average(2);
  reading = abs(reading - initial_reading);
  reading = runningAverage(reading);
  Serial.println(reading);
  //Serial.print(",");
  set_pointer(pointerServo, 0, 1000, reading);

}

void set_pointer(Servo &servo,float min_val, float max_val, float input_val) {
  // Sets the pointer to point at the input value given the full scale
  // and zero values of the scale.
  relative_position = float(input_val - min_val)/(max_val - min_val);
  servo_range = maxservo - minservo;
  absolute_position = relative_position * servo_range + minservo;
  move_servo(servo, absolute_position);
}

long runningAverage(int M)
{
  static int LM[20];      // LastMeasurements
  static byte index = 0;
  static long sum = 0;
  static byte count = 0;
  static int LMSIZE=20;
  // keep sum updated to improve speed.
  sum -= LM[index];
  LM[index] = M;
  sum += LM[index];
  index = index % LMSIZE;
  if (count < LMSIZE) count++;

  return sum / count;
}

void move_servo(Servo &servo, int position) {
  // Moves the servo to the desired position, only if it fits
  // within the safety bounds defined
  if (position > maxservo) { position = maxservo; }
  if (position < minservo) { position = minservo; }
  servo.write(position);
}