아두이노:pH미터 만들기(Gravity 아날로그 pH센서) 편집하기

{{아두이노}}

==개요==
Gravity에서 나온 pH센서들은 일반, Pro 등 버전이 다르지만 기본적으로 사용법은 같다.
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==사용법==
메카솔루션에서 잘 정리해두었다. https://blog.naver.com/roboholic84/222252612286

코드만 따로 떼어 여기에 둔다.<syntaxhighlight lang="c">
#define SensorPin A0
#define Offset 0.33  // ph7.0 측정 시 오프셋
#define LED 13
#define samplingInterval 20
#define printInterval 800
#define ArrayLenth 40

int pHArray[ArrayLenth];
int pHArrayIndex = 0;
void setup(void) {
  pinMode(LED, OUTPUT);
  Serial.begin(9600);
  Serial.println("pH meter experiment!");
}
void loop(void) {
  static unsigned long samplingTime = millis();
  static unsigned long printTime = millis();
  static float pHValue, voltage;
  if (millis() - samplingTime > samplingInterval) {
    pHArray[pHArrayIndex++] = analogRead(SensorPin);
    if (pHArrayIndex == ArrayLenth) pHArrayIndex = 0;
    voltage = avergearray(pHArray, ArrayLenth) * 5.0 / 1024;
    pHValue = 3.5 * voltage + Offset;
    samplingTime = millis();
  }
  if (millis() - printTime > printInterval) {
    Serial.print("Voltage:");
    Serial.print(voltage, 2);
    Serial.print("    pH value: ");
    Serial.println(pHValue, 2);
    digitalWrite(LED, digitalRead(LED) ^ 1);
    printTime = millis();
  }
}
double avergearray(int* arr, int number) {
  int i;
  int max, min;
  double avg;
  long amount = 0;
  if (number <= 0) {
    Serial.println("Error number for the array to avraging!/n");
    return 0;
  }
  if (number < 5) {
    for (i = 0; i < number; i++) {
      amount += arr[i];
    }
    avg = amount / number;
    return avg;
  } else {
    if (arr[0] < arr[1]) {
      min = arr[0];
      max = arr[1];
    } else {
      min = arr[1];
      max = arr[0];
    }
    for (i = 2; i < number; i++) {
      if (arr[i] < min) {
        amount += min;
        min = arr[i];
      } else {
        if (arr[i] > max) {
          amount += max;
          max = arr[i];
        } else {
          amount += arr[i];
        }
      }
    }
    avg = (double)amount / (number - 2);
  }
  return avg;
}
</syntaxhighlight>