Lora Modules

lora-modules

Goal: Establish long-range, low-power radio communication using Semtech LoRa transceivers (SX1276/SX1278, RFM95, SX1262) via SPI.

1. Hardware Interface

LoRa chips communicate via SPI and use a few extra interrupt pins to notify the MCU when a packet is received.

• SCK, MISO, MOSI -> Hardware SPI.
• NSS (Chip Select).
• RST (Reset pin).
• DIO0, DIO1 (Data Input/Output interrupts).

Logic Level: Strictly 3.3V.

2. Point-to-Point vs LoRaWAN

• LoRa (Physical Layer): Two nodes talking directly to each other using the RadioHead (RH_RF95) or LoRa library. No network joining, no encryption by default.
• LoRaWAN (MAC Layer): Connecting an edge node to public networks like The Things Network (TTN) or Helium. Requires the LMIC (LoRaMAC-in-C) library. Uses AES-128 encryption and requires AppSKey/NwkSKey provisioning.

3. Simple Point-to-Point Example (Arduino)

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

void setup() {
  Serial.begin(115200);
  // CS=10, reset=9, DIO0=2
  LoRa.setPins(10, 9, 2);

  // Initialize at 868 MHz (Europe) or 915 MHz (US)
  if (!LoRa.begin(868E6)) {
    Serial.println("Starting LoRa failed!");
    while (1);
  }
}

void loop() {
  LoRa.beginPacket();
  LoRa.print("Hello from Malskill");
  LoRa.endPacket();
  delay(10000);
}

4. Spreading Factor (SF)

You can tune the signal using LoRa.setSpreadingFactor(sf).

• SF7: Faster transmission, shorter range, less power consumption.
• SF12: Ultra-slow transmission, maximum range, punches through buildings.