ESP32 LoRa Thingspeak Gateway + LoRa Sensor Node

In this project, we will make ESP32 LoRa Thingspeak Gateway with LoRa Sensor Node. The project is basically a sensor monitoring system on Thingspeak Server using an ESP32 board & LoRa Module SX1278 or SX1276.

Overview

In the last couple of years, there is a number of communication technologies available for interaction between IoT devices. The most popular ones are the Wi-Fi Technology and Bluetooth Module. But they have few limitations like limited range, limited access points & high power consumption. So LoRa technology is introduced by Semtech to fix all these issue. Using a single battery the device operates over a year.

So, in this IoT Project, we will design ESP32 LoRa Gateway & also ESP32 LoRa Sensor Node to monitor the sensor reading wirelessly from a few kilometer distances. The sender will read the humidity and temperature data using DHT11 Sensor. Then it transmits the data via LoRa Radio. The data is received by the receiver module. The receiver will then send the data to Thingspeak Server after certain interval.

Before getting started, you can visit the following posts:
1. Interfacing SX1278 (Ra-02) LORA Module with Arduino: Check Here
2. Sending Sensor Data Wirelessly with LoRa SX1278 & Arduino: Check Here
3. ESP8266 & LoRa SX1278 Transmitter Receiver with DHT11: Check Here
4. ESP32 & LoRa SX1278/76 Transmitter Receiver with OLED: Check Here
5. ESP32 LoRa Sensor Data Monitoring on Web Server: Check Here

Bill of Materials

Following are the components required for making this project. All the components can easily be purchased from Amazon. The components purchase link is given below.

S.N.	Components Name	Quantity	Purchase Links
1	ESP32 Board	2	Amazon \| AliExpress
2	LoRa Module SX1278	2	Amazon \| AliExpress
3	DHT11 Sensor	1	Amazon \| AliExpress
4	Connecting Wires	10	Amazon \| AliExpress
5	Breadboard	1	Amazon \| AliExpress

Installing the Required Libraries

Several Libraries are required for the project to program the ESP32 Board with Arduino IDE.

1. DHT11 Library

To read the temperature and humidity we need any temperature humidity sensor. For that DHT11 is the best and cheap sensor. We need to install DHT11 Library for that. Download the library from below and add to the Arduino IDE.

Download DHT11 Library

2. LoRa Library

We need an Arduino library for sending and receiving data using LoRa radios. The library supports module like Semtech SX1276, SX1277, SX1278, SX1279 and also HopeRF RFM95W, RFM96W and RFM98W.

Download LoRa Radio Library

Circuit: ESP32 LoRa Thingspeak Gateway with LoRa Sensor Node

Now let us see the sender and receiver circuit for building ESP32 LoRa Gateway & Sensor Node. I assembled both the circuit on breadboard. You can make it on PCB if you want.

ESP32 LoRa Sensor Node

Here is an ESP32 LoRa Sensor Node Circuit with DHT11 Sensor. This part work as a transmitter. The humidity and temperature data is read by DHT11 Humidity Temperature Sensor and transmitted using LoRa Radio.

The connection is fairly simple. Simlarly connect the Lora SX1278 & ESP32 as follows.

ESP32 Pins	SX1278 Pins
GND	GND
3.3V	VCC
D5	NSS
D23	MOSI
D19	MISO
D18	SCK
D14	RST
D2	DIO0

Similarly connect the DHT11 digital input pin to GPIO4 of ESP32. Connect its VCC to 3.3V & GND to GND of ESP32.

ESP32 LoRa Thingspeak Gateway

Here is an ESP32 LoRa Module SX1278 Gateway Circuit. This part work as a Receiver. The humidity and temperature data is received using LoRa Radio & uploaded to Thingspeak Server.

The ESP32 & LoRa SX1278 connection same as above.

Setting Up Thingspeak

In order to Monitor the Sensor Data on Thingspeak Server, you first need to Setup the Thingspeak. To set up the Thingspeak Server, visit https://thingspeak.com/. Create an account or simply sign in if you created the account earlier. Then create a new channel with following details.

ESP32 LoRa Sensor Node Code

After assembling the circuit on breadboard for Sensor Node Circuit. Copy the following code and upload it to the ESP32 Board. Before uploading make sure to do the changes in the LoRa frequency according to region.

1	#define BAND 433E6 //433E6 for Asia, 866E6 for Europe, 915E6 for North America

//Libraries for LoRa

#include <SPI.h>

#include <LoRa.h>

//Libraries for LoRa

#include "DHT.h"

#define DHTPIN 4 //pin where the dht11 is connected

DHT dht(DHTPIN, DHT11);

//define the pins used by the LoRa transceiver module

#define ss 5

#define rst 14

#define dio0 2

#define BAND 433E6 //433E6 for Asia, 866E6 for Europe, 915E6 for North America

//packet counter

int readingID = 0;

int counter = 0;

String LoRaMessage = "";

float temperature = 0;

float humidity = 0;

//Initialize LoRa module

void startLoRA()

{

LoRa.setPins(ss, rst, dio0); //setup LoRa transceiver module

while (!LoRa.begin(BAND) && counter < 10) {

Serial.print(".");

counter++;

delay(500);

}

if (counter == 10)

{

// Increment readingID on every new reading

readingID++;

Serial.println("Starting LoRa failed!");

}

Serial.println("LoRa Initialization OK!");

delay(2000);

}

void startDHT()

{

if (isnan(humidity) || isnan(temperature))

{

Serial.println("Failed to read from DHT sensor!");

return;

}

void getReadings(){

humidity = dht.readHumidity();

temperature = dht.readTemperature();

Serial.print(F("Humidity: "));

Serial.print(humidity);

Serial.print(F("% Temperature: "));

Serial.print(temperature);

Serial.println(F("°C "));

}

void sendReadings() {

LoRaMessage = String(readingID) + "/" + String(temperature) + "&" + String(humidity) ;

//Send LoRa packet to receiver

LoRa.beginPacket();

LoRa.print(LoRaMessage);

LoRa.endPacket();

Serial.print("Sending packet: ");

Serial.println(readingID);

readingID++;

Serial.println(LoRaMessage);

}

void setup() {

//initialize Serial Monitor

Serial.begin(115200);

dht.begin();

startDHT();

startLoRA();

}

void loop() {

getReadings();

sendReadings();

delay(500);

}

ESP32 LoRa Gateway Code

You can now copy the below code and upload the Gateway code to ESP32 Board. In the below code make changes to WiFi SSID, Password & Thingspeak API Key.

String apiKey = "14K8UL2QEK8BTHN6"; // Enter your Write API key from ThingSpeak

const char *ssid = "Alexahome"; // replace with your wifi ssid and wpa2 key

const char *password = "12345678";

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// Import Wi-Fi library

#include <WiFi.h>

//Libraries for LoRa

#include <SPI.h>

#include <LoRa.h>

//define the pins used by the LoRa transceiver module

#define ss 5

#define rst 14

#define dio0 2

#define BAND 433E6 //433E6 for Asia, 866E6 for Europe, 915E6 for North America

// Replace with your network credentials

String apiKey = "14K8UL2QEK8BTHN6"; // Enter your Write API key from ThingSpeak

const char *ssid = "Alexahome"; // replace with your wifi ssid and wpa2 key

const char *password = "12345678";

const char* server = "api.thingspeak.com";

WiFiClient client;

// Initialize variables to get and save LoRa data

int rssi;

String loRaMessage;

String temperature;

String humidity;

String readingID;

// Replaces placeholder with DHT values

String processor(const String& var){

//Serial.println(var);

if(var == "TEMPERATURE")

{

return temperature;

}

else if(var == "HUMIDITY")

{

return humidity;

}

else if (var == "RRSI")

{

return String(rssi);

}

return String();

}

void setup() {

Serial.begin(115200);

int counter;

//setup LoRa transceiver module

LoRa.setPins(ss, rst, dio0); //setup LoRa transceiver module

while (!LoRa.begin(BAND) && counter < 10) {

Serial.print(".");

counter++;

delay(2000);

}

if (counter == 10) {

// Increment readingID on every new reading

Serial.println("Starting LoRa failed!");

}

Serial.println("LoRa Initialization OK!");

delay(2000);

// Connect to Wi-Fi network with SSID and password

Serial.print("Connecting to ");

Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {

delay(2000);

Serial.print(".");

}

// Print local IP address and start web server

Serial.println("");

Serial.println("WiFi connected.");

Serial.println("IP address: ");

Serial.println(WiFi.localIP());

}

// Read LoRa packet and get the sensor readings

void loop()

{

int packetSize = LoRa.parsePacket();

if (packetSize)

{

Serial.print("Lora packet received: ");

while (LoRa.available()) // Read packet

{

String LoRaData = LoRa.readString();

Serial.print(LoRaData);

int pos1 = LoRaData.indexOf('/');

int pos2 = LoRaData.indexOf('&');

readingID = LoRaData.substring(0, pos1); // Get readingID

temperature = LoRaData.substring(pos1 +1, pos2); // Get temperature

humidity = LoRaData.substring(pos2+1, LoRaData.length()); // Get humidity

}

rssi = LoRa.packetRssi(); // Get RSSI

Serial.print(" with RSSI ");

Serial.println(rssi);

}

if (client.connect(server, 80)) // "184.106.153.149" or api.thingspeak.com

{

String postStr = apiKey;

postStr += "&field1=";

postStr += String(readingID);

postStr += "&field2=";

postStr += String(temperature);

postStr += "&field3=";

postStr += String(humidity);

postStr += "&field4=";

postStr += String(rssi);

postStr += "\r\n\r\n\r\n\r\n";

client.print("POST /update HTTP/1.1\n");

client.print("Host: api.thingspeak.com\n");

client.print("Connection: close\n");

client.print("X-THINGSPEAKAPIKEY: " + apiKey + "\n");

client.print("Content-Type: application/x-www-form-urlencoded\n");

client.print("Content-Length: ");

client.print(postStr.length());

client.print("\n\n");

client.print(postStr);

}

//delay(30000);

}

Monitoring Sensor Data on Thingspeak Server

Once the code is uploaded, you can open the Serial Monitor on both the Gateway & Sensor Node Circuit. You will see the following output if the code is connections are correct.

Now you can visit Thingspeak Private View. There you can see the data for Packet Number, Temperature, Humidity & Gateway is uploaded after the interval of 15 seconds. You can modify the delay function in the code to change the timing of the data retrieval.

View 2 Comments

2 Comments

Andres Jaramillo on December 8, 2020 1:28 AM

Hello, good afternoon, I have a question
When I execute your code, the receiver node connects to my internet network but does not print the message of the received packets, the temperature, humidity and the rssi. Maybe you know why it is?

sandeep singh on May 12, 2021 11:10 PM

sir i am not able to receive the data on lora gateway code is correct everything is correct can you tell me