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프로세싱과 보드를 연동, Firmata | Main | 적외선 센서/LED


Smoothing


센서에서 신호를 입력받을 때 급격한 신호변화나 노이즈가 생길 수 있습니다. 아래 예제는 순차적으로 입력받은 신호의 평균을 계산해서 신호를 안정화시킵니다.

/*
  Smoothing
  Reads repeatedly from an analog input, calculating a running average
  and printing it to the computer.  Keeps ten readings in an array and 
  continually averages them.
  
  The circuit:
    * Analog sensor (potentiometer will do) attached to analog input 0

  Created 22 April 2007
  By David A. Mellis  

  http://www.arduino.cc/en/Tutorial/Smoothing


*/


// Define the number of samples to keep track of.  The higher the number,
// the more the readings will be smoothed, but the slower the output will
// respond to the input.  Using a constant rather than a normal variable lets
// use this value to determine the size of the readings array.
const int numReadings = 10;

int readings[numReadings];      // the readings from the analog input
int index = 0;                  // the index of the current reading
int total = 0;                  // the running total
int average = 0;                // the average

int inputPin = 0;

void setup()
{
  // initialize serial communication with computer:
  Serial.begin(9600);                   
  // initialize all the readings to 0: 
  for (int thisReading = 0; thisReading < numReadings; thisReading++)
    readings[thisReading] = 0;          
}

void loop() {
  // subtract the last reading:
  total= total - readings[index];         
  // read from the sensor:  
  readings[index] = analogRead(inputPin); 
  // add the reading to the total:
  total= total + readings[index];       
  // advance to the next position in the array:  
  index = index + 1;                    

  // if we're at the end of the array...
  if (index >= numReadings)              
    // ...wrap around to the beginning: 
    index = 0;                           

  // calculate the average:
  average = total / numReadings;         
  // send it to the computer (as ASCII digits) 
  Serial.println(average, DEC);               
}

Posted by tokage at July 16, 2008 12:02 AM