#include <WiFi.h>
#include <HTTPClient.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED display width and height
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

// Create display object
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
#define VOLTAGE_SENSOR_PIN A2   // ADC pin for voltage sensor
#define CURRENT_SENSOR_PIN A0  // ADC pin for ACS712 current sensor

#define REF_VOLTAGE 3.3  // ESP32-C3 operates on 3.3V
#define ADC_RESOLUTION 4095  // 12-bit ADC (0-4095)

#define SENSITIVITY 185  // Set this based on your ACS712 module: (5A = 185mV/A, 20A = 100mV/A, 30A = 66mV/A)
#define VOLTAGE_DIVIDER_FACTOR 4.3  // Adjust based on calibration

const int numSamples = 200;  
float zeroPoint = 0;  

// Replace with your WiFi credentials
const char* ssid = "FABLAB";
const char* password = "12345678";

// Replace with your ThingSpeak Write API Key
const char* apiKey = "9HO2SSQ4PUUDVWAY";

// ThingSpeak API URL
const char* server = "http://api.thingspeak.com/update";

void setup() {
Serial.begin(115200);
if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // 0x3C is the I2C address
Serial.println(F("SSD1306 allocation failed"));
while (1); // Halt execution
}

display.clearDisplay();
display.setTextSize(2);
display.setTextColor(SSD1306_WHITE);
pinMode(VOLTAGE_SENSOR_PIN, INPUT);
pinMode(CURRENT_SENSOR_PIN, INPUT);
delay(500);

// Calibrate Zero Point (Idle Voltage when NO Load)
long sum = 0;
for (int i = 0; i < numSamples; i++) {
sum += analogReadMilliVolts(CURRENT_SENSOR_PIN);
delay(5);
}
zeroPoint = sum / numSamples;
Serial.print("Zero Point (No Load): ");
Serial.print(zeroPoint);
Serial.println(" mV");


WiFi.begin(ssid, password);

Serial.print("Connecting to WiFi...");
while (WiFi.status() != WL_CONNECTED) {
Serial.print(".");
delay(100);
}
Serial.println("\nConnected to WiFi!");
}
// Function to measure AC Current RMS correctly
float readACCurrent() {
float sumSquared = 0;
for (int i = 0; i < numSamples; i++) {
float voltage = analogReadMilliVolts(CURRENT_SENSOR_PIN);  
float current = (voltage - zeroPoint) / SENSITIVITY;  
sumSquared += current * current;
delayMicroseconds(50);  // Sampling rate improvement
}
return sqrt(sumSquared / numSamples);  // RMS Current Calculation
}

// Function to measure Voltage
float readVoltage() {
int adcValue = analogRead(VOLTAGE_SENSOR_PIN);
float voltage = (adcValue * REF_VOLTAGE) / ADC_RESOLUTION;  
return voltage * VOLTAGE_DIVIDER_FACTOR;  // Adjust with divider factor
}
void loop() {
if (WiFi.status() == WL_CONNECTED) {
HTTPClient http;
float voltage = readVoltage();  
float current = readACCurrent();  
float power = voltage * current;  // Power Calculation: P = V * I
display.clearDisplay();
display.setCursor(0, 0);
display.print("volt=");
display.setCursor(70, 0);
display.print(voltage);
display.setCursor(0, 18);
display.print("Amp=");
display.setCursor(60, 18);
display.print(current);
display.setCursor(0, 40);
display.print("power=");
display.setCursor(80, 40);
display.print(power);
display.display();
Serial.print("Voltage: ");
Serial.print(voltage);
Serial.print(" V  |  AC Current: ");
Serial.print(current, 3);
Serial.print(" A  |  Power: ");
Serial.print(power, 3);
Serial.println(" W");
// Generate random values
float value1 = voltage;  // Example: Temperature
float value2 = current;  // Example: Humidity
float value3 =power; // Example: Light Intensity

// Construct the request URL
String url = String(server) + "?api_key=" + apiKey + 
            "&field1=" + String(value1) + 
            "&field2=" + String(value2) + 
            "&field3=" + String(value3);

Serial.println("Sending data to ThingSpeak...");
Serial.println(url);

// Send data to ThingSpeak
http.begin(url);
int httpCode = http.GET();

if (httpCode > 0) {
  Serial.println("Data sent successfully!");
} else {
  Serial.println("Failed to send data.");
}

http.end();
} else {
Serial.println("WiFi Disconnected!");
}

delay(500); // ThingSpeak allows updates every 15 seconds
}