Tutorial

be 4.00.If you measure the alkaline sample, the pH value of the standard solution should be 9.18.Subsection
calibration, just in order to get a better accuracy.
Before the pH electrode measured different solutions, we need to use water to wash it. We recommend using
deionized water.
(1)Connect equipments according to the graphic,that is,the pH electrode is connected to the BNC connector on the pH
meter boardand then use the connection lines,the pH meter board is connected to the ananlong port 0 of the Arduino
controller. When the Arduino controller gets power,you will see the blue LED on board is on.
(2)Upload the sample code to the Arduino controller.
(3)Put the pH electrode into the standard solution whose pH value is 7.00or directly shorted the input of the BNC
connector.Open the serial monitor of the Arduino IDE,you can see the pH value printed on it,and the error does not
exceed 0.3. Record the pH value printed,then compared with 7.00, and the difference should be changed into the
"Offset" in the sample code. For example,the pH value printed is 6.88,so the difference is 0.12.You should change the
"# define Offset 0.00" into "# define Offset 0.12" in your program.
(4)Put the pH electrode into the pH standard solution whose value is 4.00.Then wait about one minute,adjust the gain
potential device, let the value stabilise at around 4.00.At this time,the acidic calibration has been completed and you
can measure the pH value of an acidic solution.
Note:If you want to measure the pH value of other solution,you must wash the pH electrode first!
(5) According to the linear characteristics of pH electrode itself, after the above calibration,you can directly measure
the pH value of the alkaline solution, but if you want to get better accuracy, you can recalibrate it. Alkaline calibration
use the standard solution whose pH value is 9.18.Also adjust the gain potential device, let the value stabilise at around
9.18. After this calibration, you can measure the pH value of the alkaline solution.
Sample Code
Sample code for testing the PH meter and get the sensor feedback from the Arduino Serial Monitor.
/*
# This sample code is used to test the pH meter V1.0.
# Editor : YouYou
# Ver : 1.0
# Product: analog pH meter
# SKU : SEN0161
*/
#define SensorPin A0 //pH meter Analog output to Arduino Analog Input 0
#define Offset 0.00 //deviation compensate
#define LED 13
#define samplingInterval 20
#define printInterval 800
#define ArrayLenth 40 //times of collection
int pHArray[ArrayLenth]; //Store the average value of the sensor feedback
int pHArrayIndex=0;
void setup(void)
{
pinMode(LED,OUTPUT);
Serial.begin(9600);
Serial.println("pH meter experiment!"); //Test the serial monitor
}
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) //Every 800 milliseconds, print a numerical, convert the state of the LED indicator
{
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;