I need help with my Gravity PH sensor. The problem i'm facing is that i only get ph value of 6 to 7 even when i put the probe into a ph 4 buffer solution. I've done the calibration but its not doing anything, it says buffer solution 7 even though its 4. Please help, i'm super new to this

this is the pin connection

VCC - 5.v

gnd - gnd

data pin - GPIO 2

and these are my code

#include "DFRobot_ESP_PH.h"

#include "EEPROM.h"

DFRobot_ESP_PH ph;

#define ESPADC 4096.0 // the esp Analog Digital Conversion value

#define ESPVOLTAGE 3300 // the esp voltage supply value

#define PH_PIN 2 // the esp gpio data pin number

float voltage, phValue;

const float fixedTemperature = 25.0; // constant temperature for pH calculation

void setup() {

Serial.begin(115200);

EEPROM.begin(32); // needed to permit storage of calibration value in eeprom

ph.begin();

// Calibration configuration

ph.calibration(0.78, 7.0); // voltage value for pH 7 solution

ph.calibration(1.036, 4.0); // voltage value for pH 4 solution

}

void loop() {

static unsigned long timepoint = millis();

if (millis() - timepoint > 1000U) // time interval: 1s

{

timepoint = millis();

// Read raw analog value from the pH sensor

int rawPinValue = analogRead(PH_PIN);

Serial.print("Raw Pin Value: ");

Serial.println(rawPinValue);

// Convert raw pin value to voltage

voltage = rawPinValue / ESPADC * ESPVOLTAGE;

Serial.print("Voltage: ");

Serial.println(voltage, 4);

// Convert voltage to pH value with a fixed temperature

phValue = ph.readPH(voltage, fixedTemperature);

Serial.print("pH: ");

Serial.println(phValue, 4);

}

delay(2000); // Delay for 2 seconds (2000 milliseconds)

}