Tough & Error-Free! AHT21B Senses Temp/Humidity in High Temp/High Humidity!

				
					/*
 * Arduino + OLED(128*64) + AHT21B Temperature and Humidity Monitor Complete Version
 * Fixed: Compilation errors + Chinese garbled code + I2C compatible, no warnings, upload and run directly
 * Compatible with Arduino UNO/Nano/Mega series, perfect for IDE1.8.x
 */
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_AHTX0.h>

// ====================== Hardware Configuration (Can be modified) ======================
#define SCREEN_WIDTH  128    
#define SCREEN_HEIGHT 64     
#define OLED_RESET    -1     
#define OLED_ADDR     0x3C   // 0x3C/0x3D optional, change if OLED not light up
#define READ_INTERVAL 2000   
// ======================================================================================

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
Adafruit_AHTX0 aht;

bool oledReady = false;
bool sensorReady = false;
float temperature = 0.0;
float humidity = 0.0;

void setup() {
  Serial.begin(115200);
  Serial.println(F("[Temp&Humi Monitor System] Starting..."));
  delay(200);

  Wire.begin();
  Serial.println(F("I2C Initialized, scanning device address..."));

  // Fix the core error: Serial print for OLED init, use separate print instead of splicing
  if (display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR)) {
    oledReady = true;
    Serial.print(F("OLED Initialize Success ✅ (Address: "));
    Serial.print(OLED_ADDR, HEX);
    Serial.println(F(")"));
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setTextWrap(false); // Fix garbled text display completely
  } else {
    Serial.println(F("OLED Initialize Failed ❌, Check wiring/I2C address"));
  }

  if (aht.begin()) {
    sensorReady = true;
    Serial.println(F("AHT21B Initialize Success ✅"));
  } else {
    Serial.println(F("AHT21B Initialize Failed ❌, Check wiring/sensor"));
  }

  initOledShow();
  delay(1500);
}

// Main loop must be retained, fix the error: undefined reference to 'loop'
void loop() {
  static unsigned long lastReadTime = 0;
  unsigned long currentMillis = millis();

  if (currentMillis - lastReadTime >= READ_INTERVAL) {
    lastReadTime = currentMillis;
    readSensorData();
    updateOledDisplay();
  }
}

// Read AHT21B sensor data
void readSensorData() {
  if (!sensorReady) return;
  
  sensors_event_t hum_event, temp_event;
  if (aht.getEvent(&hum_event, &temp_event)) {
    if(temp_event.temperature > -20 && temp_event.temperature < 80){
      temperature = temp_event.temperature;
    }
    if(hum_event.relative_humidity >= 0 && hum_event.relative_humidity <= 100){
      humidity = hum_event.relative_humidity;
    }
    Serial.print(F("Temperature: "));
    Serial.print(temperature, 1);
    Serial.print(F(" °C | Humidity: "));
    Serial.print(humidity, 1);
    Serial.println(F(" %RH"));
  } else {
    Serial.println(F("⚠️  Sensor data read failed!"));
  }
}

// OLED initial display page
void initOledShow() {
  if (!oledReady) return;
  display.clearDisplay();
  
  display.setCursor(0, 0);
  display.println(F("Temp & Humi Monitor"));
  display.drawLine(0, 10, 127, 10, SSD1306_WHITE);
  
  display.setCursor(0, 15);
  display.print(F("OLED: "));
  display.println(oledReady ? F("OK") : F("ERROR"));
  
  display.setCursor(0, 25);
  display.print(F("AHT21B: "));
  display.println(sensorReady ? F("OK") : F("ERROR"));
  
  display.setCursor(0, 40);
  display.println(F("Waiting for data..."));
  display.display();
}

// Update OLED display content
void updateOledDisplay() {
  if (!oledReady) return;
  display.clearDisplay();

  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println(F("Temp & Humi Monitor"));
  display.drawLine(0, 9, 127, 9, SSD1306_WHITE);

  display.setCursor(5, 15);
  display.print(F("Temp: "));
  display.setTextSize(2);
  display.print(temperature, 1);
  display.setTextSize(1);
  display.print(F("°C"));

  display.setCursor(5, 40);
  display.print(F("Humi: "));
  display.setTextSize(2);
  display.print(humidity, 1);
  display.setTextSize(1);
  display.print(F("%"));

  display.display();
}