// example 4, master+ssd1306+DS18B20
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
String myString;

#include <OneWire.h> 
#include <DallasTemperature.h>
#define ONE_WIRE_BUS 2 
OneWire oneWire(ONE_WIRE_BUS); 
DallasTemperature sensors(&oneWire);

void setup() 
{  
  // DS18B20 setup
  sensors.begin(); 
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);// Address 0x3C for 128x64
  display.clearDisplay();
  display.display();
  SPI.begin();                            //Begins the SPI commnuication
  SPI.setClockDivider(SPI_CLOCK_DIV8);    //Sets clock for SPI communication at 8 (16/8=2Mhz)
  digitalWrite(SS,HIGH);                  // Setting SlaveSelect as HIGH (So master doesnt connnect with slave)
} 

void loop() 
{ 
  sensors.requestTemperatures();
  myString=String(sensors.getTempCByIndex(0));
  drawChar(myString+" oC"); 
  byte Mastersend,Mastereceive;         
  digitalWrite(SS, LOW);                  //Starts communication with Slave connected to master
  Mastersend = sensors.getTempCByIndex(0);                            
  Mastereceive=SPI.transfer(Mastersend); //Send the mastersend value to slave also receives value from slave
} 

 void drawChar(String str) {
  display.clearDisplay();
  display.setTextSize(2);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw white text
  display.setCursor(0, 0);     // Start at top-left corner
  display.cp437(true);         // Use full 256 char 'Code Page 437' font
  display.print(str);
  display.display();
}

//// example 4, slave+ESP8266
//#include <SPI.h>
//volatile boolean received;
//volatile byte Slavereceived, Slavesend;
//
//String AP = "Guest";       // AP NAME. Change it to the AP you are using. You can even use the your smartphone's hotspot. 
//String PASS = ""; // AP PASSWORD. At FLC, the Guest AP doesn't need a password
//String API = "YBFFEGYDGI54K3WN"; // Must be your ThingSpeak channel's API. 
//String HOST = "api.thingspeak.com";
//String PORT = "80";
//int countTrueCommand;
//int countTimeCommand; 
//boolean found = false; 
//int valSensor = 1;
//
//void setup() 
//{  
//  // ESP8266 setup
//  Serial.begin(115200); // ESP setup 
//  sendCommand("AT+RST",5,"OK");
//  sendCommand("AT",5,"OK");
//  sendCommand("AT+CWMODE=1",5,"OK");
//  String cmd = F("AT+CWJAP=\"");
//  cmd += AP;
//  cmd += F("\",\"");
//  cmd += PASS;
//  cmd += F("\"");
//  sendCommand(cmd,20,"OK"); 
//  
//  // SPI setup
//  pinMode(MISO,OUTPUT);                   //Sets MISO as OUTPUT (Have to Send data to Master IN 
//  SPCR |= _BV(SPE);                       //Turn on SPI in Slave Mode
//  received = false;
//  SPI.attachInterrupt();                  //Interrupt ON is set for SPI commnucation
//} 
//
//void loop() 
//{ 
//   if(received){ // if any SPI signal was received                         
//        byte sensorByte=Slavereceived;//integer data in F is ready
//        if (sensorByte!=185 && sensorByte!=-196){// Avoid the two error temperatures
//          String sensorByteStr = String(sensorByte);  
//          String getData = "GET /update?api_key="+ API +"&field1="+sensorByteStr; // send to ThingSpeak, needs to be a string
//          sendCommand("AT+CIPMUX=1",5,"OK");
//          sendCommand("AT+CIPSTART=0,\"TCP\",\""+ HOST +"\","+ PORT,15,"OK");
//          sendCommand("AT+CIPSEND=0," +String(getData.length()+4),4,">");
//          Serial.println(getData);
//          countTrueCommand++;
//        sendCommand("AT+CIPCLOSE=0",5,"OK");  
//      }
//   }
//} 
//
//ISR (SPI_STC_vect)  //Interrupt routine function 
//{
//  Slavereceived = SPDR; // Value received from master if store in variable slavereceived
//  received = true;      //Sets received as True 
//}
//
//void sendCommand(String command, int maxTime, char readReplay[]){// send data to ESP8266
//  while(countTimeCommand < (maxTime*1))
//  {
//    Serial.println(command);//at+cipsend
//    if(Serial.find(readReplay))//ok
//    {
//      found = true;
//      break;
//    }  
//    countTimeCommand++;
//  }  
//  if(found == true)
//  {
//    countTrueCommand++;
//    countTimeCommand = 0;
//  }  
//  if(found == false)
//  {
//    countTrueCommand = 0;
//    countTimeCommand = 0;
//  }  
//  found = false;
// }