/***************************************************************************
  This is a library for the BME280 humidity, temperature & pressure sensor
  Designed specifically to work with the Adafruit BME280 Breakout
  ----> http://www.adafruit.com/products/2650
  These sensors use I2C or SPI to communicate, 2 or 4 pins are required
  to interface. The device's I2C address is either 0x76 or 0x77.
  Adafruit invests time and resources providing this open source code,
  please support Adafruit andopen-source hardware by purchasing products
  from Adafruit!
  Written by Limor Fried & Kevin Townsend for Adafruit Industries.
  BSD license, all text above must be included in any redistribution
 ***************************************************************************/

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include <SD.h>

#define BME_SCK 13
#define BME_MISO 12
#define BME_MOSI 11
#define BME_CS 10
#define SD_CS 9

#define SEALEVELPRESSURE_HPA (1013.25)
// Calculated from https://barani.biz/apps/sea-level-pressure/

//Adafruit_BME280 bme; // I2C
Adafruit_BME280 bme(BME_CS); // hardware SPI
//Adafruit_BME280 bme(BME_CS, BME_MOSI, BME_MISO, BME_SCK); // software SPI

unsigned long delayTime;

void setup() {
    Serial.begin(9600);
    Serial.println(F("BME280 test"));

    bool status;

    // default settings
    // (you can also pass in a Wire library object like &Wire2)
    status = bme.begin();  
    if (!status) {
        Serial.println("Could not find a valid BME280 sensor, check wiring!");
        while (1);
    }

    Serial.print("Initializing SD card...");

    // see if the card is present and can be initialized:
    if (!SD.begin(SD_CS)) {
        Serial.println("Card failed, or not present");
        // don't do anything more:
        while (1);
    }
    Serial.println("card initialized.");


    Serial.println("-- Default Test --");
    delayTime = 1000;

    Serial.println();
}


void loop() { 
    String dataString = printValues();

    File dataFile = SD.open("datalog.txt", FILE_WRITE);

    // if the file is available, write to it:
    if (dataFile) {
        dataFile.println(dataString);
        dataFile.close();
        // print to the serial port too:
//        Serial.println(dataString);
    }
    // if the file isn't open, pop up an error:
    else {
        Serial.println("error opening datalog.txt");
    }

    delay(delayTime);
}


String printValues() {
    String dataString = "";
    char str_temp[7];

    Serial.print("Temperature = ");
    Serial.print(bme.readTemperature());
    Serial.println(" *C");
    dtostrf(bme.readTemperature(), 4, 2, str_temp);
    dataString = String(str_temp);

    Serial.print("Pressure = ");
    Serial.print(bme.readPressure() / 100.0F);
    Serial.println(" hPa");
    dtostrf((bme.readPressure() / 100.0F), 4, 2, str_temp);
    dataString += "," + String(str_temp);

    Serial.print("Approx. Altitude = ");
    Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
    Serial.println(" m");

    Serial.print("Humidity = ");
    Serial.print(bme.readHumidity());
    Serial.println(" %");
    dtostrf(bme.readHumidity(), 4, 2, str_temp);
    dataString += "," + String(str_temp);

    Serial.println();
//    Serial.println(dataString);

    return(dataString);
}