/**
 * BME280-OLED
 *
 * By: Mike Klepper
 * Date: 31 March 2017
 *
 * This program reads data from the BMP280 and shows it on a
 * SSD1306 OLED display. It will alternte between British and
 * metric units.
 *
 * See blog post on patriot-geek.blogspot.com
 * for connections.
 */

#include "Wire.h"
#include "Adafruit_Sensor.h"
#include "Adafruit_BME280.h"
#include "SSD1306.h"

const float SEA_LEVEL_PRESSURE_HPA = 1013.25;
const int DELAY = 3000;
const int STARTUP_DELAY = 500;


Adafruit_BME280 bme;

SSD1306 display(0x3C, 4, 5);

void setup()
{
  Serial.begin(115200);

  if(!bme.begin())
  {
    Serial.println("Could not find a valid BME280 sensor, check wiring!");
    while (1)
    {
        yield();
        delay(DELAY);
    }
  }
  delay(STARTUP_DELAY);

  display.init();
  display.flipScreenVertically();

}

void loop()
{
  float tempC = bme.readTemperature();
  float humidity = bme.readHumidity();
  float pressurePascals = bme.readPressure();

  // Print to serial monitor
  printToSerial(tempC, humidity, pressurePascals);

  // Display data on screen in British units
  drawWithBritishUnits(tempC, humidity, pressurePascals);
  yield();
  delay(DELAY);

  // Display data on screen in metric units
  drawWithMetricUnits(tempC, humidity, pressurePascals);
  yield();
  delay(DELAY);
}


void drawWithBritishUnits(float tempC, float humidity, float pressurePascals)
{
  float tempF = 9.0/5.0 * tempC + 32.0;
  float pressureInchesOfMercury = 0.000295299830714 * pressurePascals;

  display.clear();

  display.drawRect(0, 0, DISPLAY_WIDTH, DISPLAY_HEIGHT);

  display.setFont(ArialMT_Plain_16);
  display.drawString(35, 3, "BME280");

  display.setFont(ArialMT_Plain_10);
  display.drawString(5, 22, "Temperature = " + String(tempF) + " *F");
  display.drawString(5, 35, "Humidity = " + String(humidity) + "%");
  display.drawString(5, 48, "Pressure = " + String(pressureInchesOfMercury) + " inHg");

  display.display();
}

void drawWithMetricUnits(float tempC, float humidity, float pressurePascals)
{
  float pressureHectoPascals = pressurePascals / 100.0;

  display.clear();

  display.drawRect(0, 0, DISPLAY_WIDTH, DISPLAY_HEIGHT);

  display.setFont(ArialMT_Plain_16);
  display.drawString(35, 3, "BME280");

  display.setFont(ArialMT_Plain_10);
  display.drawString(5, 22, "Temperature = " + String(tempC) + " *C");
  display.drawString(5, 35, "Humidity = " + String(humidity) + "%");
  display.drawString(5, 48, "Pressure = " + String(pressureHectoPascals) + " h,Pa");

  display.display();
}

void printToSerial(float tempC, float humidity, float pressurePascals)
{
    // Temperature
    float tempF = 9.0/5.0 * tempC + 32.0;

    Serial.println("Temperature:");
    printValueAndUnits(tempC, "*C");
    printValueAndUnits(tempF, "*F");
    //printValueAndUnits(tempC, "°C");
    //printValueAndUnits(tempF, "°F");
    Serial.println("");

    // Barometric pressure
    float pressureHectoPascals = pressurePascals / 100.0;
    float pressureInchesOfMercury = 0.000295299830714 * pressurePascals;

    Serial.println("Pressure:");
    printValueAndUnits(pressurePascals, "Pa");
    printValueAndUnits(pressureHectoPascals, "hPa");
    printValueAndUnits(pressureInchesOfMercury, "inHg");
    Serial.println("");

    // Humidity
    Serial.println("Humidity:");
    printValueAndUnits(humidity, "%");
    Serial.println("");

    // Approximate altitude
    float altitudeMeters = bme.readAltitude(SEA_LEVEL_PRESSURE_HPA);
    float altitudeFeet = 3.28 * altitudeMeters;

    Serial.println("Approx. Altitude:");
    printValueAndUnits(altitudeMeters, "m");
    printValueAndUnits(altitudeFeet, "ft");
    Serial.println();
}

void printValueAndUnits(float value, String units)
{
    Serial.print("     ");
    Serial.print(value);
    Serial.print(" ");
    Serial.println(units);
}