// Forum: https://forum.arduino.cc/t/oled-ssd1306-works-fine-on-esp32c-but-not-on-nano-328p-with-the-same-resolution/1215937
// This Wokwi project: https://wokwi.com/projects/387937940405058561

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_BME680.h"
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define BME_SCK 13
#define BME_MISO 12
#define BME_MOSI 11
#define BME_CS 10

#define SEALEVELPRESSURE_HPA (1013.25)
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

Adafruit_BME680 bme; // I2C
//Adafruit_BME680 bme(BME_CS); // hardware SPI
//Adafruit_BME680 bme(BME_CS, BME_MOSI, BME_MISO,  BME_SCK);

//Adafruit_SSD1306 display = Adafruit_SSD1306();
Adafruit_SSD1306 display = Adafruit_SSD1306(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin(9600);
  Serial.println(F("BME680 test"));

  // by default, we'll generate the high voltage from the 3.3v line internally! (neat!)
  //display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr 0x3C (for the 128x32)
  //display.begin(0x3C, false);
  
  Serial.print(F("freeMemory before OLED initialization: "));
  Serial.println(freeMemory());

 if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C))
  {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  
  // init done
  display.display();
  delay(100);
  display.clearDisplay();
  display.display();
  display.setTextSize(1);
  display.setTextColor(WHITE);

  Serial.print(F("freeMemory after OLED initialization: "));
  Serial.println(freeMemory());

  if (!bme.begin()) {
    Serial.println("Could not find a valid BME680 sensor, check wiring!");
    while (1);
  }

  // Set up oversampling and filter initialization
  bme.setTemperatureOversampling(BME680_OS_8X);
  bme.setHumidityOversampling(BME680_OS_2X);
  bme.setPressureOversampling(BME680_OS_4X);
  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
  bme.setGasHeater(320, 150); // 320*C for 150 ms
}

void loop() {
  /*

  display.setCursor(0,0);
  display.clearDisplay();

  if (! bme.performReading()) {
    //Serial.println("Failed to perform reading :(");
    return;
  }
  //display.println("--------------------");
  //display.println("** Sensor BME680 **");
  //display.println("--------------------");
  
  //Serial.print("Temperature = "); 
  //Serial.print(bme.temperature); 
  //Serial.println(" *C");
  display.print(F("Temp: ")); 
  display.print(bme.temperature); 
  display.println(F(" *C"));

  //Serial.print("Pressure = "); 
  //Serial.print(bme.pressure / 100.0); 
  //Serial.println(" hPa");
  display.print(F("Pres: ")); 
  display.print(bme.pressure / 100); 
  display.println(F(" hPa"));

  //Serial.print(F("Humidity = ")); 
  //Serial.print(bme.humidity); 
  //Serial.println(F(" %"));
  display.print(F("Humi: ")); 
  display.print(bme.humidity); 
  display.println(F(" %"));

  //Serial.print(F("Gas = ")); 
  //Serial.print(bme.gas_resistance / 1000.0); 
  //Serial.println(F(" KOhms"));
  display.print(F("Gas : ")); 
  display.print(bme.gas_resistance / 1000.0); 
  display.println(F(" KOhms"));

  display.println(F("--------------------"));
  //Serial.println();
  display.display();

  */

  delay(2000);
}


#ifdef __arm__
// should use uinstd.h to define sbrk but Due causes a conflict
extern "C" char* sbrk(int incr);
#else  // __ARM__
extern char *__brkval;
#endif  // __arm__

int freeMemory() {
  char top;
#ifdef __arm__
  return &top - reinterpret_cast<char*>(sbrk(0));
#elif defined(CORE_TEENSY) || (ARDUINO > 103 && ARDUINO != 151)
  return &top - __brkval;
#else  // __arm__
  return __brkval ? &top - __brkval : &top - __malloc_heap_start;
#endif  // __arm__
}