Published December 13, 2020 © GPL3+

LoRa Blynk app Interfacing

Sending The Data From The LoRa Modules To Blynk Servers Using Ai-Thinker LoRa Modules

IntermediateFull instructions provided6 hours3,584

Things used in this project

Hardware components

DFRobot FireBeetle ESP32 IOT Microcontroller (Supports Wi-Fi & Bluetooth)

NodeMCU ESP8266 Breakout Board

ElectroPeak 0.96" OLED 64x128 Display Module

DHT11 Temperature & Humidity Sensor (3 pins)

Ai-Thinker Ra-02 LoRa Module

433 Mhz Antenna

LM1117 3.3 V REGULATOR

LED (generic)

Resistor 1k ohm

Software apps and online services

Arduino IDE

Blynk

Hand tools and fabrication machines

Soldering iron (generic)

Solder Wire, Lead Free

PCB Holder, Soldering Iron

Solder Flux, Soldering

Storage Case, General Purpose

Multitool, Screwdriver

Wire Stripper & Cutter, 18-10 AWG / 0.75-4mm² Capacity Wires

Story

Connecting LoRa with cloud Requires LoRaWAN Gateway is a bit Costlier and does not have any mobile phone application to visualize the received data. relying on the web dashboard to see the received data every time is not handy. In order to overcome these issues, I have Interfaced LoRa modules with Blynk App.

Here in this project, I am using two separate circuits to transmit the data using LoRa, Receiving, and retransmitting the data to Blynk. I am using Ai-Thinker Ra-02 LoRa modules in this project.

in order to test the project, I am using a DHT11 sensor as an input and sending the temperature and humidity details to the cloud server through the Lora module and internet.

To test the operating range I have kept the Transmitter 1.5 Km away from the receiver at that time received signal sensitivity is - 100 dB.

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in this project, I am using ESP32 instead of the Arduino series microcontroller because of the Logic voltage level difference(Arduino microcontroller logic voltage level is 5 volt), the Ai-Thinker Ra 02 modules work on 3.3-volt logic voltage level. The difference in logic voltage level creates the communication problem between the LoRa and microcontroller hence I have chosen the ESP32 and NodeMCU where the logic voltage levels of both the microcontroller are 3.3volt.

To transmit the data and Receiving data I am utilizing the Arduino Json V6 library. this library helps to receive the data and helps to process the data easily.

Transmitter Section

In this transmitter section, I am using ESP32, OLED, Temperature, and humidity sensor, Ai-Thinker Ra 02 LoRa Module. this transmitter section part collects the temperature and humidity data from the DHT11 and transmits the data using Ai-Thinker Ra 02 LoRa module and displays data on the OLED Display.

Transmitter Section Block diagram

Transmitter Section Front View

Receiver and Retransmitting Section

In this section, I am using NodeMCU and receiving the data from the LoRa Module. in order to retransmit the received data to the cloud server(Blynk Server), I am using the internet connection by utilizing the Wi-fi function of the Nodemcu. the NodeMCU transmits the data to the server's predefined virtual ports. On the Blynk App, we can analyze the received data and can be store those data for future references.

To analyze the signal sensitivity of the receiver I am sending the RSSI details to the virtual Port where we can analyze the Signal sensitivity in the graph.

Receiver Section Block Diagram

Receiver Circuit

A View of LoRa Module Unplugged from the Board

Blynk App Output

Code

#define BLYNK_PRINT Serial
#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include <SPI.h>
#include <LoRa.h>
#include <ArduinoJson.h>  //REQUIRES ARDUINO JSON V6

//define the pins used by the transceiver module
#define ss 15  //D8 Of NodeMCU
#define rst 16 //D0 Of Nodemcu
#define dio0 2  //D2 Of Nodemcu

String LoRaData;
String jsonBuffer;
float ta;// Temperature details 
float ha; // Humidity details
float rs; //Rssi details

char auth[] = "Your blynk app token id";// Your blynk app token id
char ssid[] = "Wifi name"; // your Wifi name
char pass[] = "wifi password"; // your wifi password

BlynkTimer timer;

void setup() {
  Serial.begin(9600);
  while (!Serial);
  Serial.println("LoRa Receiver");
  LoRa.setPins(ss, rst, dio0);

  while (!LoRa.begin(433E6)) {
    Serial.println("LoRa Intialization problem");
    delay(500);
  }
  LoRa.setSyncWord(0xF3);
  Serial.println("LoRa Initializing OK!");
  Blynk.begin(auth, ssid, pass);
  timer.setInterval(1000L, sendSensor);
}

void loop() {
  int packetSize = LoRa.parsePacket();
  if (packetSize) {
    while (LoRa.available()) {
      LoRaData = LoRa.readString();
      }
    StaticJsonDocument<300> doc;
    DeserializationError err = deserializeJson(doc, LoRaData);
    
    if (err == DeserializationError::Ok)
    {
      Serial.print("Temperature:");
      Serial.print(doc["DATA1"].as<float>());
      Serial.println();
      Serial.print("Humidity:");
      Serial.print(doc["Humidity"].as<float>());
      Serial.println();
      ta = (doc["DATA1"].as<float>()); // temperature details recieving 
      ha = (doc["Humidity"].as<float>());//Humidity details receiving
      rs = (LoRa.packetRssi());
      }
      }
      Blynk.run();
      timer.run();
      }
      
      void sendSensor()
      {
        Blynk.virtualWrite(V0,ta);
        Blynk.virtualWrite(V1,ha);
        Blynk.virtualWrite(V2,rs);
        }

#include <SPI.h>
#include <LoRa.h>
#include <ArduinoJson.h> //REQUIRES ARDUINO JSON V6
#include<String.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_Sensor.h>
#include <DHT.h>
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
unsigned long startMillis = 0; 
const long interval = 1000;
#define DHTPIN 4     // Digital pin connected to the DHT sensor
float t;
float h;
#define ss 5
#define rst 14
#define dio0 2
#define DHTTYPE  DHT11
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  LoRa.setPins(ss, rst, dio0);
  while (!Serial);
  Serial.println("LoRa Sender");

  if (!LoRa.begin(433E6)) {
    Serial.println("Starting LoRa failed!");
    while (1);
  }

  LoRa.setTxPower(20);
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  delay(1000);
  display.clearDisplay();
  display.setTextColor(WHITE);
  dht.begin();
}

void loop() {
  t = dht.readTemperature();
  h = dht.readHumidity();
  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
  }
  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.print("Temperature: ");
  display.setTextSize(2);
  display.setCursor(0, 10);
  display.print(t);
  display.print(" ");
  display.setTextSize(1);
  display.cp437(true);
  display.write(167);
  display.setTextSize(2);
  display.print("C");
  display.setTextSize(1);
  display.setCursor(0, 35);
  display.print("Humidity: ");
  display.setTextSize(2);
  display.setCursor(0, 45);
  display.print(h);
  display.print(" %");
  display.display();
  
//Serializing the Data to transmit using LoRa

  StaticJsonDocument<100> testDocument;
  testDocument["DATA1"] = t;
  testDocument["Humidity"] = h;
  char buffer[100];
  LoRa.beginPacket();
  LoRa.print(buffer);
  LoRa.endPacket();
  serializeJson(testDocument, buffer);
  Serial.print("Sending packet:");
  Serial.print(buffer);
}