How to Use Dfrobot gravity : ph meter: Examples, Pinouts, and Specs

The DFRobot Gravity: pH Meter (SEN0169V2) is a sensor module designed to measure the pH level of a solution. It is widely used in various applications such as environmental monitoring, aquaponics, hydroponics, and other scientific research fields. This module provides a simple and cost-effective way to measure the acidity or alkalinity of a solution, making it an essential tool for hobbyists and professionals alike.

1. Connect the pH Sensor to the Arduino UNO:

   • Connect the VCC pin of the pH sensor to the 5V pin on the Arduino.
   • Connect the GND pin of the pH sensor to the GND pin on the Arduino.
   • Connect the AOUT pin of the pH sensor to an analog input pin (e.g., A0) on the Arduino.

2. Calibrate the pH Sensor:

   • Immerse the pH probe in a standard buffer solution (e.g., pH 7.0).
   • Adjust the potentiometer on the sensor module until the output voltage corresponds to the pH value of the buffer solution.

3. Write and Upload the Arduino Code:

   • Use the following sample code to read the pH value from the sensor and display it on the serial monitor.

// DFRobot Gravity: pH Meter (SEN0169V2) Sample Code
// Connect the pH sensor to analog pin A0

#define SensorPin A0  // Define the analog pin for the pH sensor
#define Offset 0.00   // Define the offset value for calibration
#define SamplingInterval 20  // Sampling interval in milliseconds
#define PrintInterval 800    // Print interval in milliseconds
#define ArrayLength 40       // Length of the sample array

int pHArray[ArrayLength];    // Array to store pH readings
int pHArrayIndex = 0;        // Index for the pH array

void setup() {
  Serial.begin(9600);  // Initialize serial communication
  pinMode(SensorPin, INPUT);  // Set the sensor pin as input
}

void loop() {
  static unsigned long samplingTime = millis();
  static unsigned long printTime = millis();
  static float pHValue, voltage;

  if (millis() - samplingTime > SamplingInterval) {
    samplingTime = millis();
    pHArray[pHArrayIndex++] = analogRead(SensorPin);  // Read the sensor value
    if (pHArrayIndex == ArrayLength) pHArrayIndex = 0;
  }

  if (millis() - printTime > PrintInterval) {
    printTime = millis();
    voltage = averageArray(pHArray, ArrayLength) * 5.0 / 1024;  // Convert to voltage
    pHValue = 3.5 * voltage + Offset;  // Convert voltage to pH value
    Serial.print("Voltage: ");
    Serial.print(voltage, 2);
    Serial.print("V  pH Value: ");
    Serial.println(pHValue, 2);
  }
}

float averageArray(int* arr, int number) {
  int i;
  int max, min;
  float avg;
  long amount = 0;
  if (number <= 0) {
    Serial.println("Error: Array length must be greater than 0");
    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 = (float)amount / (number - 2);
  }
  return avg;
}

• Calibration: Regularly calibrate the pH sensor using standard buffer solutions to ensure accurate readings.
• Cleaning: Clean the pH probe with distilled water after each use to prevent contamination.
• Storage: Store the pH probe in a storage solution to maintain its sensitivity and accuracy.
• Temperature: Be aware that temperature can affect pH readings. Use a temperature compensation method if necessary.

1. Inaccurate Readings:

   • Solution: Ensure the sensor is properly calibrated using standard buffer solutions. Check for any contamination on the probe and clean it if necessary.

2. No Output or Fluctuating Readings:

   • Solution: Verify all connections between the sensor and the Arduino. Ensure the probe is fully immersed in the solution and not touching the container walls.

3. Slow Response Time:

   • Solution: Allow the probe to stabilize in the solution for at least one minute before taking readings. Ensure the probe is clean and free from any deposits.

• Check Connections: Ensure all connections are secure and correctly placed.
• Calibrate Regularly: Regular calibration is essential for accurate measurements.
• Clean the Probe: Rinse the probe with distilled water after each use to prevent contamination.
• Use Fresh Buffer Solutions: Always use fresh and uncontaminated buffer solutions for calibration.

By following this documentation, users can effectively utilize the DFRobot Gravity: pH Meter (SEN0169V2) in their projects, ensuring accurate and reliable pH measurements.