Wireless Lora RF Receiver Module Ra-02 Ai-Thinker 10KM 433MHZ SX1278

Features

• LoRa modulation using advanced RF technology for long-range communication
• SPI communication interface for easy microcontroller integration
• Mandatory external antenna connection
• Up to 10 km communication range (with 1 MHz bandwidth channel)
• Operating frequency: 433 MHz
• High receiver sensitivity: -136 dBm
• Maximum output power: +20 dBm
• Supports data rates up to 300 kbps
• Excellent blocking immunity in noisy RF environments
• Preamble detection for efficient packet reception
• Automatic RF Sense and CAD (Channel Activity Detection)
• Built-in clock recovery with bit synchronizer
• Packet engine supports up to 256-byte packets with CRC
• Built-in temperature sensor
• Ultra-low standby current: 1 µA

Specifications

• Frequency Range: 433 MHz
• Modulation: FSK / GFSK / MSK / LoRa
• Supply Voltage: 3.3 V (DO NOT use 5 V)
• Sensitivity: -136 dBm
• Output Power: +20 dBm
• Data Rate: < 300 kbps
• Dynamic Range RSSI: 127 dB
• Working Temperature: -40°C to +80°C
• Standby Current: 1 µA

Principle of Operation

LoRa (Long Range) technology uses Chirp Spread Spectrum (CSS) modulation, where data is encoded into chirp signals that sweep across frequencies. This technique provides high resistance to noise and interference, enabling long-range, low-power communication.

• Preamble & Chirp Detection: Enables reliable synchronization between transmitter and receiver
• Reverse Chirp: Signals the start of data transmission
• Robust Modulation: Maintains communication over long distances with minimal power

Pinout

Circuit Diagram

Warning: Always power the module with 3.3 V only. Do NOT connect to 5 V.

Library Installation (Arduino)

• Open Arduino IDE
• Go to Sketch → Include Library → Manage Libraries
• Search for LoRa by Sandeep Mistry
• Click Install

Example Code

Transmitter Code

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

int pot = A0;

void setup() {
  Serial.begin(9600);
  pinMode(pot, INPUT);
  while (!Serial);

  if (!LoRa.begin(433E6)) {
    while (1);
  }
}

void loop() {
  int val = map(analogRead(pot), 0, 1024, 0, 255);
  LoRa.beginPacket();
  LoRa.print(val);
  LoRa.endPacket();
  delay(50);
}

Receiver Code

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

int LED = 3;
String inString = "";
int val = 0;

void setup() {
  Serial.begin(9600);
  pinMode(LED, OUTPUT);
  while (!Serial);

  if (!LoRa.begin(433E6)) {
    while (1);
  }
}

void loop() {
  int packetSize = LoRa.parsePacket();
  if (packetSize) {
    while (LoRa.available()) {
      inString += (char)LoRa.read();
    }
    val = inString.toInt();
    inString = "";
  }
  analogWrite(LED, val);
}

Applications

• IoT and smart sensor networks
• Home and building automation
• Long-range remote monitoring
• Industrial monitoring and control
• Environmental and agricultural monitoring
• Smart metering systems
• Security and surveillance systems
• Mesh and star topology networks
• Amateur radio and experimental projects

Comparison

• SX1278 (433 MHz): External antenna, up to 10 km range
• RFM95 (916 MHz): Different frequency band, configurable bandwidth, often integrated antenna