How to apply a median filter with a time window of 500ms in particle photon

Troubleshooting
1

I am using particle photon to read the data from GSR sensor. I want to add a median filter and a mean filter in my code to remove the frequency noise and the rapid-transient noise. Then use the data with less noise to find the suddenly changed gap. However, I am new in particle photon and Arduino. I found some example code about the median filter and mean filter, but I don’t know how to combine them in my code. Does anyone know how to do that? or if there is a library to do that? Thank you in advance.

The following is the example code of the median filter and mean filter. (Arduino code)

int Filter_Value; // median filter
  
void setup() {
  Serial.begin(9600);       
  randomSeed(analogRead(0)); 
}
  
void loop() {
  Filter_Value = Filter();       
  Serial.println(Filter_Value); 
  delay(50);
}
  
int Get_AD() {
  return random(295, 305);
}
  
#define FILTER_N 101
int Filter() {
  int filter_buf[FILTER_N];
  int i, j;
  int filter_temp;
  for(i = 0; i < FILTER_N; i++) {
    filter_buf[i] = Get_AD();
    delay(1);
  }

  for(j = 0; j < FILTER_N - 1; j++) {
    for(i = 0; i < FILTER_N - 1 - j; i++) {
      if(filter_buf[i] > filter_buf[i + 1]) {
        filter_temp = filter_buf[i];
        filter_buf[i] = filter_buf[i + 1];
        filter_buf[i + 1] = filter_temp;
      }
    }
  }
  return filter_buf[(FILTER_N - 1) / 2];
}

int Filter_Value; // mean filter
  
void setup() {
  Serial.begin(9600);      
  randomSeed(analogRead(0));
}
  
void loop() {
  Filter_Value = Filter();    
  Serial.println(Filter_Value);
  delay(50);
}
  
int Get_AD() {
  return random(295, 305);
}
  
#define FILTER_N 12
int Filter() {
  int i;
  int filter_sum = 0;
  for(i = 0; i < FILTER_N; i++) {
    filter_sum += Get_AD();
    delay(1);
  }
  return (int)(filter_sum / FILTER_N);
}

The following part is my current code:

int gsr = A2;
int gsrV, gsrV2;

void setup(){
pinMode(gsr , INPUT);
}

void loop(){
gsrV = analogRead(gsr);
delay(1000);
gsrV2 = analogRead(gsr);
int temp = abs(gsrV - gsrV2);
}

In my code, “gsrV” and “gsrV2” are the raw data. Is that possible to create a function with median filter and mean filter to remove the noise in raw data first, then trasnfer these value to “gsrV” and “gsrV2” ?

2

This library works:

1 Like
3

Thank you for your reply.