ESP32 LoRa Long-Range Sensor Node — Up to 15 km on a Battery

WiFi range tops out at ~100 m. LoRa reaches 2–15 km (line of sight) on a CR2032 battery — making it the go-to choice for agriculture sensors, asset tracking, smart meter reading, and any outdoor IoT deployment where WiFi or cellular is impractical.

Hardware Required

Wiring — SX1278 to ESP32

Library Setup

Install the LoRa library by Sandeep Mistry from the Arduino Library Manager.

Transmitter Node Sketch

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

#define LORA_SS   5
#define LORA_RST  14
#define LORA_DIO0 2
#define SOIL_PIN  34  // analog soil moisture sensor

int packetCount = 0;

void setup() {
  Serial.begin(115200);
  LoRa.setPins(LORA_SS, LORA_RST, LORA_DIO0);
  if (!LoRa.begin(433E6)) {     // 433 MHz — change to 868E6 or 915E6 as needed
    Serial.println("LoRa init failed!");
    while (true);
  }
  LoRa.setSpreadingFactor(9);   // SF9 — good balance of range vs speed
  LoRa.setSignalBandwidth(125E3);
  LoRa.setCodingRate4(5);
  Serial.println("LoRa transmitter ready.");
}

void loop() {
  int soil = map(analogRead(SOIL_PIN), 4095, 1500, 0, 100); // % moisture
  float temp = (float)(analogRead(35)) * 0.1;               // placeholder

  String payload = String(packetCount) + "," +
                   String(soil) + "," +
                   String(temp, 1);

  LoRa.beginPacket();
  LoRa.print(payload);
  LoRa.endPacket();

  Serial.printf("Sent packet #%d: %s\n", packetCount, payload.c_str());
  packetCount++;
  delay(60000); // transmit every 60 seconds
}

Gateway / Receiver Sketch

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

// Same pin definitions as transmitter
#define LORA_SS 5; #define LORA_RST 14; #define LORA_DIO0 2;

const char* SSID = "YOUR_SSID"; const char* PASSWORD = "YOUR_PASSWORD";
const char* MQTT_HOST = "192.168.1.10";
WiFiClient wifiClient; PubSubClient mqtt(wifiClient);

void setup() {
  Serial.begin(115200);
  WiFi.begin(SSID, PASSWORD);
  while (WiFi.status() != WL_CONNECTED) delay(500);
  mqtt.setServer(MQTT_HOST, 1883);
  LoRa.setPins(5, 14, 2);
  LoRa.begin(433E6);
  LoRa.setSpreadingFactor(9);  // must match transmitter
  Serial.println("Gateway listening...");
}

void loop() {
  if (!mqtt.connected()) { mqtt.connect("lora-gateway"); }
  mqtt.loop();

  int packetSize = LoRa.parsePacket();
  if (packetSize) {
    String received = "";
    while (LoRa.available()) received += (char)LoRa.read();
    int rssi = LoRa.packetRssi();
    Serial.printf("Received: %s  RSSI: %d dBm\n", received.c_str(), rssi);
    mqtt.publish("lora/sensor/data", received.c_str());
    mqtt.publish("lora/sensor/rssi", String(rssi).c_str());
  }
}

Spreading Factor Reference