ESP-1ch-Gateway/libraries/Heltec_ESP32_Dev-Boards/examples/LoRa/LoRaSetSyncWord/LoRaSetSyncWord.ino

/*
  Heltec.LoRa Duplex communication with Sync Word

  Sends a message every half second, and polls continually
  for new incoming messages. Sets the Heltec.LoRa radio's Sync Word.

  Spreading factor is basically the radio's network ID. Radios with different
  Sync Words will not receive each other's transmissions. This is one way you
  can filter out radios you want to ignore, without making an addressing scheme.

  See the Semtech datasheet, http://www.semtech.com/images/datasheet/sx1276.pdf
  for more on Sync Word.

  by Aaron.Lee from HelTec AutoMation, ChengDu, China
  成都惠利特自动化科技有限公司
  www.heltec.cn
  
  this project also realess in GitHub:
  https://github.com/Heltec-Aaron-Lee/WiFi_Kit_series
*/
#include "heltec.h"
#define BAND    433E6  //you can set band here directly,e.g. 868E6,915E6

byte msgCount = 0;            // count of outgoing messages
int interval = 2000;          // interval between sends
long lastSendTime = 0;        // time of last packet send

void setup()
{
  //WIFI Kit series V1 not support Vext control
  Heltec.begin(true /*DisplayEnable Enable*/, true /*Heltec.Heltec.Heltec.LoRa Disable*/, true /*Serial Enable*/, true /*PABOOST Enable*/, BAND /*long BAND*/);
 
  LoRa.setSyncWord(0xF3);           // ranges from 0-0xFF, default 0x34, see API docs
  Serial.println("Heltec.LoRa init succeeded.");
}

void loop()
{
  if (millis() - lastSendTime > interval)
  {
    String message = "HeHeltec.LoRa World! ";   // send a message
    message += msgCount;
    sendMessage(message);
    Serial.println("Sending " + message);
    lastSendTime = millis();            // timestamp the message
    interval = random(2000) + 1000;    // 2-3 seconds
    msgCount++;
  }

  // parse for a packet, and call onReceive with the result:
  onReceive(LoRa.parsePacket());
}

void sendMessage(String outgoing)
{
  LoRa.beginPacket();                   // start packet
  LoRa.print(outgoing);                 // add payload
  LoRa.endPacket();                     // finish packet and send it
  msgCount++;                           // increment message ID
}

void onReceive(int packetSize)
{
  if (packetSize == 0) return;          // if there's no packet, return

  // read packet header bytes:
  String incoming = "";
 
  while (LoRa.available())
  {
    incoming += (char)LoRa.read();
  }

  Serial.println("Message: " + incoming);
  Serial.println("RSSI: " + String(LoRa.packetRssi()));
  Serial.println("Snr: " + String(LoRa.packetSnr()));
  Serial.println();
}