water_temp/reciver/lora_reciver/src/main.cpp

// OLED
#include <Wire.h>  // Only needed for Arduino 1.6.5 and earlier
#include "SSD1306.h" // alias for `#include "SSD1306Wire.h"`

// LORA
#include <SPI.h>
#include <LoRa.h>

// MQTT
#include <WiFi.h>
#include <PubSubClient.h>


SSD1306 display(0x3c, 4, 15);

//OLED pins to ESP32 GPIOs via this connection:
//OLED_SDA GPIO4
//OLED_SCL GPIO15
//OLED_RST GPIO16

 

// WIFI_LoRa_32 ports

// GPIO5  SX1278 SCK
// GPIO19 SX1278 MISO
// GPIO27 SX1278 MOSI
// GPIO18 SX1278 CS
// GPIO14 SX1278 RESET
// GPIO26 SX1278 IRQ(Interrupt Request)

#define SS 18
#define RST 14
#define DI0 26
// #define BAND 429E6

// LoRa Settings 
#define BAND 434500000.00
#define spreadingFactor 9
// #define SignalBandwidth 62.5E3
#define SignalBandwidth 31.25E3

#define codingRateDenominator 8



// WiFi Network Credentials
const char *ssid =  "SoS IOT";   
const char *password =  "godisr8n"; 

// MQTTCredentials
const char *MQTT_USER = "simon";
const char *MQTT_PASS = "bajsa123";

IPAddress broker(10,0,0,3); // IP address of your MQTT broker eg. 192.168.1.50
const char *ID = "esp_1";  // Name of our device, must be unique
const char *TOPIC = "test/sensor";  // Topic to subcribe to
WiFiClient wclient;

PubSubClient client(wclient); // Setup MQTT client

String data = "";

// Connect to WiFi network
void setup_wifi() {
  Serial.print("\nConnecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password); // Connect to network

  while (WiFi.status() != WL_CONNECTED) { // Wait for connection
    delay(500);
    Serial.print(".");
  }

  Serial.println();
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

// Reconnect to client
void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect(ID,MQTT_USER,MQTT_PASS)) {
      Serial.println("connected");
      Serial.print("Publishing to: ");
      Serial.println(TOPIC);
      Serial.println('\n');

    } else {
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}



// ADC? Battery voltage
// const uint8_t vbatPin = 34;
// float VBAT;  // battery voltage from ESP32 ADC read
  
void setup() {
  pinMode(16,OUTPUT);
  digitalWrite(16, LOW); // set GPIO16 low to reset OLED
  delay(50);
  digitalWrite(16, HIGH);

  display.init();
  display.flipScreenVertically();
  display.setFont(ArialMT_Plain_10);
  display.setTextAlignment(TEXT_ALIGN_LEFT);
  
  Serial.begin(115200);
  while (!Serial); //if just the the basic function, must connect to a computer
  delay(1000);
  
  Serial.println("LoRa Receiver");
  display.drawString(5,5,"LoRa Receiver");
  display.display();
  SPI.begin(5,19,27,18);
  LoRa.setPins(SS,RST,DI0);

/*     
  pinMode(vbatPin, INPUT);
  VBAT = (120.0/20.0) * (float)(analogRead(vbatPin)) / 1024.0; // LiPo battery voltage in volts
  Serial.println("Vbat = "); Serial.print(VBAT); Serial.println(" Volts");
*/

  if (!LoRa.begin(BAND)) {
    display.drawString(5,25,"Starting LoRa failed!");
    while (1);
  }
  Serial.println("LoRa Initial OK!");
  
  Serial.print("LoRa Frequency: ");
  Serial.println(BAND);
  
  Serial.print("LoRa Spreading Factor: ");
  Serial.println(spreadingFactor);
  LoRa.setSpreadingFactor(spreadingFactor);
  
  Serial.print("LoRa Signal Bandwidth: ");
  Serial.println(SignalBandwidth);
  LoRa.setSignalBandwidth(SignalBandwidth);

  LoRa.setCodingRate4(codingRateDenominator);
  
  display.drawString(5,25,"LoRa Initializing OK!");
  display.display();
  
  setup_wifi(); // Connect to network
  client.setServer(broker, 1883);
}

void loop() {
  if (!client.connected())  // Reconnect if connection is lost
  {
    reconnect();
  }
  client.loop();
  // try to parse packet
  int packetSize = LoRa.parsePacket();
  if (packetSize) {
    // received a packets
    Serial.print("Received packet. ");
    
    display.clear();
    display.setFont(ArialMT_Plain_16);
    display.drawString(3, 0, "Received packet ");
    display.display();
    
    // read packet
    while (LoRa.available()) {
      data = LoRa.readString();
      Serial.print(data);
      display.drawString(20,22, data);
      display.display();
    }
    
    // print RSSI of packet
    Serial.print(" with RSSI ");
    Serial.println(LoRa.packetRssi());
    Serial.print(" with SNR ");
    Serial.println(LoRa.packetSnr());
    // display.drawString(0, 45, "RSSI: ");
    // display.drawString(50, 45, (String)LoRa.packetRssi());
    
    display.drawString(0, 45, (String)LoRa.packetRssi() + "dB (" + (String)LoRa.packetSnr() +"dB)");
        
    display.display();
    client.publish(TOPIC, data.c_str() );
    Serial.println((String)TOPIC + " => " + data  + ";");
  }
}