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//modified lora library by Sandeep Mistry for Lora32U4
// lora receiverCallBack modified by hwthinker
 #include <SPI.h>
#include <LoRa.h>
 #ifdef ARDUINO_SAMD_MKRWAN1300
#error "This example is not compatible with the Arduino MKR WAN 1300 board!"
#endif
 // GPIO5  -- SX1278's SCK
// GPIO19 -- SX1278's MISO
// GPIO27 -- SX1278's MOSI
// GPIO18 -- SX1278's CS
// GPIO14 -- SX1278's RESET
// GPIO26 -- SX1278's IRQ(Interrupt Request)
 #define SS      8
#define RST     4
#define DI0     7
#define BAND    433E6  
 void setup() {
  Serial.begin(115200);
  //while (!Serial); disable for LORA32U4
//  SPI.begin(5,19,27,18);
  LoRa.setPins(SS,RST,DI0);
   Serial.println("LoRa Receiver Callback");
   if (!LoRa.begin(BAND)) {
    Serial.println("Starting LoRa failed!");
    while (1);
  }
   // register the receive callback
  LoRa.onReceive(onReceive);
   // put the radio into receive mode
  LoRa.receive();
}
 void loop() {
  // do nothing
}
 void onReceive(int packetSize) {
  // received a packet
  Serial.print("Received packet '");
   // read packet
  for (int i = 0; i < packetSize; i++) {
    Serial.print((char)LoRa.read());
  }
   // print RSSI of packet
  Serial.print("' with RSSI ");
  Serial.println(LoRa.packetRssi());
}