Making pedometer with accelerometer

Projects Programming
1

Hi everyone, I want to make pedometer with ADXL345 and ARDUINO UNO board. I am using ADXL345 with Full resolution

  Wire.beginTransmission(ADXL345); // Start communicating with the device
  Wire.write(0x31);
  Wire.write(0x0B);
  Wire.endTransmission();

and

Wire.beginTransmission(ADXL345);
  Wire.write(0x2C);
  Wire.write(0x09); //For low power 000x x pin set to 1  /1001 determine Hz
  Wire.endTransmission();

According to datasheet, I am using it with Output Data Rate = 50 and Bandwidth (Hz) =25 .

So data rate 20 ms I guess. When I checked the pedometer codes, they use like

delay(200);
delay(50);

How can I determine good delay ?

My codes full code here

void loop() {
  // === Read acceleromter data === //
  Wire.beginTransmission(ADXL345);
  Wire.write(0x32); // Start with register 0x32 (ACCEL_XOUT_H)
  Wire.endTransmission(false);
  Wire.requestFrom(ADXL345, 6, true); // Read 6 registers total, each axis value is stored in 2 registers
  X_out = ( Wire.read() | Wire.read() << 8); // X-axis value
  X = X_out /256; //For a range of +-2g, we need to divide the raw values by 256, according to the datasheet
  Y_out = ( Wire.read() | Wire.read() << 8); // Y-axis value
  Y = Y_out /256;
  Z_out = ( Wire.read() | Wire.read() << 8); // Z-axis value
  Z = Z_out /256;

  ave = sqrt((X - xave) * (X - xave) + (Y - yave) * (Y - yave) + (Z - zave) * (Z - zave));//  ave = sqrt(x*x + y*y +z*z); 

  if(sampling == 0)
  {
    maxave = ave;
    minave = ave;
  }

  else if(maxave < ave)
  {
    maxave = ave;
  }

  else if(minave > ave)
  {
    minave = ave;
  }

  sampling++;

  if(sampling >= 20)
  {
    threshold = (maxave + minave) / 2 + 0.3;
    sampling = 0;
  }
delay(200);

Screen Shot 2022-11-21 at 14.25.41

Red line = threshold value and blue line steps of mine. I made 14 steps in this graph. If we count the peak values, it is equal 16 I guess.

I have 2 question.
How can I determine good delay ?

threshold = (maxave + minave) / 2 + 0.3;

As you can see, I am using a fixed value (0.3). How can I make this dynamic ? If I don't choose a fixed value, anyone can use it.

2

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