/*
  Reads temperature from HT11 sensor and writes to SD card
  SD card read/write via LC Technology SD Module (www.lctech-inc.com)
 
 * SD card attached to SPI bus as follows:
 ** MOSI - pin 11
 ** MISO - pin 12
 ** SCK  - pin 13
 ** CS   - pin 4
 ** GND  - GND
 ** +3.3 - 3.3V
 
 HT11 Sensor is wired per below. Note: with checked openings facing you,
 pin 1 is to the left.
 ** PIN 1 - 3.3V or 5V
 ** PIN 2 - Data (to pins attached below (probably 2)
 ** PIN 3 - NC
 ** PIN 4 - Ground
 
 This example code is in the public domain.
 
 */
#define SOFTWARE_SPI 1
#define ITERATIONS 25
 
#include <SD.h>         // SD Card library
#include <dht11.h>      // DHT111 temperature probe Library
 
dht11 DHT11;
 
 
File myFile;
 
void shutdown()
{
        // add you emergency shutdown code here
        while (1); // endless loop
}
 
void setup()
{
// Open serial communications and wait for port to open:
        Serial.begin(9600);
        DHT11.attach(2);
        Serial.println("DHT11 TEST PROGRAM ");
        Serial.print("LIBRARY VERSION: ");
        Serial.println(DHT11LIB_VERSION);
 
 
        Serial.print("Initializing SD card...");
        // On the Ethernet Shield, CS is pin 4. It's set as an output by default.
        // Note that even if it's not used as the CS pin, the hardware SS pin
        // (10 on most Arduino boards, 53 on the Mega) must be left as an output
        // or the SD library functions will not work.
        pinMode(10, OUTPUT);
 
        if (!SD.begin(4)) {
                Serial.println("initialization failed!");
                return;
        }
 
        Serial.println("initialization done.");
 
        // open the file. note that only one file can be open at a time,
        // so you have to close this one before opening another.
        myFile = SD.open("temps.txt", FILE_WRITE);
 
        // if the file opened okay, write to it:
        if (!myFile) {
            // if the file didn't open, print an error:
            Serial.println("error opening file - Halting system");
            shutdown();
        }
 
        Serial.print("Test limited to ");
        Serial.print(ITERATIONS, DEC);
        Serial.println(" temperature readings");
        Serial.println("File on SD created, temperature tests will now start");
}
 
void loop()
{
        int n, chk;
 
        myFile.println("Test of LC Technology SD Module and DFRobot DHT11 Temperature & Humidity Sensor");
        myFile.print("Test limited to ");
        myFile.print(ITERATIONS, DEC);
        myFile.println(" temperature readings");
        for (n = 0; n < ITERATIONS; n++) {
                chk = DHT11.read();
                Serial.print("Sensor read: ");
                myFile.print("\nSensor read: ");
 
                switch (chk) {
                case 0:
                        Serial.println("OK");
                        myFile.println("OK");
                        myFile.print("Humidity (%): ");
                        myFile.println((float)DHT11.humidity, DEC);
 
                        myFile.print("Temperature (");
                        myFile.print((char)176);        // Print degree symbol
                        myFile.print("C): ");
                        myFile.println((float)DHT11.temperature, DEC);
 
                        myFile.print("Temperature (");
                        myFile.print((char)176);
                        myFile.print("F): ");
                        myFile.println(DHT11.fahrenheit(), DEC);
 
                        myFile.print("Temperature (");
                        myFile.print((char)176);
                        myFile.print("K): ");
                        myFile.println(DHT11.kelvin(), DEC);
 
                        myFile.print("Dew Point (");
                        myFile.print((char)176);
                        myFile.print("C): ");
                        myFile.println(DHT11.dewPoint(), DEC);
 
                        myFile.print("Dew PointFast (");
                        myFile.print((char)176);
                        myFile.print("C): ");
                        myFile.println(DHT11.dewPointFast(), DEC);
                        break;
 
                case -1:
                        Serial.println("Checksum error");
                        Serial.println("Checksum error");
                        break;
 
                case -2:
                        Serial.println("Time out error");
                        myFile.println("Time out error");
                        break;
 
                default:
                        Serial.println("Unknown error");
                        myFile.println("Unknown error");
                        break;
                }
                delay(2000);    // 2-second pause
        }
        Serial.println("Test Complete - Halting system");
        myFile.close();
        shutdown();
}