Ph sensor connect to arduino

[juhina]

Why when connect ph with arduino give me wrong values?

What correct code

[build_1971]

Please read the forum guidelines.
Tell us about your specific sensor, your wiring and your current code...
And the results you get...

[juhina]

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <SimpleTimer.h>

SimpleTimer timer;

float calibration_value = 21.34 - 0.7;
int phval = 0;
unsigned long int avgval;
int buffer_arr[10],temp;

float ph_act;
// for the OLED display

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void setup()
{
Wire.begin();
Serial.begin(9600);
display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
display.clearDisplay();
display.setTextColor(WHITE);

timer.setInterval(500L, display_pHValue);
}
void loop() {
timer.run(); // Initiates SimpleTimer
for(int i=0;i<10;i++)
{
buffer_arr[i]=analogRead(A0);
delay(30);
}
for(int i=0;i<9;i++)
{
for(int j=i+1;j<10;j++)
{
if(buffer_arr[i]>buffer_arr[j])
{
temp=buffer_arr[i];
buffer_arr[i]=buffer_arr[j];
buffer_arr[j]=temp;
}
}
}
avgval=0;
for(int i=2;i<8;i++)
avgval+=buffer_arr[i];
float volt=(float)avgval*5.0/1024/6;
ph_act = -5.70 * volt + calibration_value;

Serial.println("pH Val: ");
Serial.print(ph_act);
delay(1000);
}

void display_pHValue()
{
// display on Oled display

// Oled display
display.clearDisplay();
display.setTextSize(2);
display.setCursor(0,0); // column row
display.print("pH:");

display.setTextSize(2);
display.setCursor(55, 0);
display.print(ph_act);

/*
display.setTextSize(2);
display.setCursor(0,30);
display.print("EC:");

display.setTextSize(2);
display.setCursor(60, 30);
display.print(345);
display.setCursor(95, 50);
*/
display.display();
}

This the code which I use it

The ph value showing

0.7and it not change

[van_der_decken]

Please take a few minutes and read the forum guidelines at How to get the best out of this forum.

Please use code tags.

Give us a link to the datasheet for your sensor, or at least a link to the page where you bought it from. No one here can read minds: we don't know what sensor you're using until you tell us.