LoRa Peer to Peer: LoRa for P2P Wireless Communication

The Internet of Things connects things together. The connection can be based on different protocols such as MQTT, AMQP, HTTP, CoAP, LoRaWAN, or Cellular communication. In this blog, we will learn what LoRa communication is, how LoRa is used for P2P (peer-to-peer) wireless communication, and how to make a P2P communication between two LoRa modules using ESP32 by doing a hands-on example.

What is LoRa for P2P Communication

LoRa stands for long-range, which is the modulation technique using chirp spread spectrum (CSS). This modulation technique is generally used by LoRaWAN (long-range wireless network) to communicate at long range using minimal energy consumption.

LoRa is highly effective in areas with limited or insufficient WiFi or cellular communication networks, such as remote locations, agricultural fields, and environmental monitoring.

To understand the LoRa P2P communication, it is important to understand the LoRaWAN architecture. LoRa operates in unlicensed sub-GHz frequency bands (e.g., 868 MHz in Europe, 915 MHz in the U.S.), enabling long-range communication with minimal energy consumption.

The architecture of LoRaWAN uses the stars-of-stars topology and consists of End devices, Gateways, Network servers, and Application servers.

LoRaWAN architecture

In the LoRaWAN architecture, the data flows from End devices to the application server or reversed, but in P2P communication is when two P2P devices communicate with each other or make connections as shown in the following figure, device 1 and device 5 is making a P2P communication.

LoRa Peer-to-Peer communication

In the next section, we will use the LoRa module with ESP32 to make a P2P communication using ESP32.

LoRa Peer-to-Peer Project Example

For this example and the demonstration of P2P communication, we will use two LoRa RYLR993 modules and connect them to ESP32. RYLR993 LoRa modules are from REYAX which support multiple frequency bands, low power consumption, and long range.

Interfacing ESP32 with RYLR993 module

The LoRa module is connected to the ESP32 using Serial communication. Both ESP32s will be connected to the RYLR993 module in the following way:

Interfacing ESP32 with RYLR993 module

The connections in the above figure are as follows,

• 3.3V: LoRa module's power supply pin to the 3.3V pin on the ESP32.
• GND: LoRa module's ground pin to the GND pin on the ESP32.
• RX: LoRa module's RX (receive) pin to the D5 pin on the ESP32.
• TX: LoRa module's TX (transmit) pin to the D4 pin on the ESP32.

Next, we will upload the code to both ESP32s using Arduino IDE.

Code Uploading

Then using the Arduino IDE, we will upload the following code to the ESP32s one by one. One ESP32 will be configured with Address 1 and the other with Address 2.

// Include the necessary library
#include <HardwareSerial.h>

// Create an instance of HardwareSerial
HardwareSerial ReyaxLoRaSerial(1);

void sendATCommand(String command, String expectedResponse, unsigned long timeout = 1000) {
  ReyaxLoRaSerial.println(command);
  unsigned long startTime = millis();
  String response = "";

  while (millis() - startTime < timeout) {
    if (ReyaxLoRaSerial.available()) {
      response += (char)ReyaxLoRaSerial.read();
    }
    if (response.indexOf(expectedResponse) != -1) {
      Serial.println("[OK] " + command);
      return;
    }
  }

  Serial.println("[ERROR] " + command);
  Serial.println("Response: " + response);
}

void setup() {
  // Initialize the primary hardware serial port for monitoring
  Serial.begin(115200);
  Serial.println();
  delay(2000);

  // Initialize the secondary hardware serial port for communication with Reyax LoRa
  // Parameters are (TX pin, RX pin)
  ReyaxLoRaSerial.begin(9600, SERIAL_8N1, 4, 5); // Change 4 and 5 to the pins you want to use

  delay(1000);

  Serial.println("Initializing Reyax LoRa Module...");

  // Send AT commands to configure the device
  sendATCommand("AT", "OK");
  sendATCommand("AT+OPMODE=1", "OK"); // Set to proprietary mode
  sendATCommand("AT+ADDRESS=1", "OK"); // Set device address to 1 for device 1 and 2 for device 2
  sendATCommand("AT+BAND=923000000", "RESET"); // Set frequency band and expect reset prompt

  Serial.println("Reyax LoRa Module Initialized.");
  Serial.println("Serial monitor settings:");
  Serial.println("- End Char  : Newline");
  Serial.println("- Baud Rate : 115200");
  Serial.println();
}

void loop() {
  static unsigned long lastSendTime = 0;
  unsigned long currentTime = millis();

  // Send a message every 2 minutes
  if (currentTime - lastSendTime >= 120000) {
    lastSendTime = currentTime;
    sendATCommand("AT+SEND=2,30,Hello from Arduino IDE ESP32", "OK"); //change AT+send=1 to send message to device 1 and AT+send=2 to send message to device 2
  }

  // Read data from ReyaxLoRa and send it to Serial monitor
  if (ReyaxLoRaSerial.available()) {
    Serial.println(ReyaxLoRaSerial.readString());
  }

  // Read data from Serial monitor and send it to ReyaxLoRa
  if (Serial.available()) {
    ReyaxLoRaSerial.print(Serial.readString());
  }
}

The above code requires AT commands for setup. AT commands are text-based instructions used to configure communication modules like LoRa, manage settings, and handle data transmission.

To view the received and sent messages, you can use the Arduino Serial monitor.

Note: Make sure to change the address of the device in the code.

sendATCommand("AT+ADDRESS=1", "OK"); // Set device address to 1 for device 1 and 2 for device 2 and make sure to change the device address while sending the message.

sendATCommand("AT+SEND=2,30,Hello from Arduino IDE ESP32", "OK"); //change AT+send=1 to send message to device 1 and AT+send=2 to send message to device 2

This hands-on example demonstrates how two LoRa modules can be used for P2P communication. P2P communication simplifies the system while retaining the key benefits of LoRa technology, such as long-distance connectivity, low power consumption, and enhanced security and privacy.

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Conclusion

This blog introduces the LoRa technique for Peer-to-Peer communication and uses a simple LoRa Peer-to-Peer example, which can be extended with the interfacing of sensors to send real data. If you have questions about your LoRa P2P or any other IoT project, chat with PCBONLINE from the online chat window.