lora-project/gateway/receiver.js

var SX127x = require('sx127x'); // or require('sx127x')

var sx127x = new SX127x({
  frequency: 866e6,
  resetPin: 17,
  dio0Pin: 4,
  syncWord: 0x22,
  crc: true
});

var count = 0;

// open the device
sx127x.open(function(err) {
  console.log('open', err ? err : 'success');

  if (err) {
    throw err;
  }

  // add a event listener for data events
  sx127x.on('data', function(data, rssi) {
    //console.log('Origin Data: ', data, data.length);
    console.log('data:', '\'' + data.toString() + '\'', rssi);
    let json = {};
    try{
	    json = JSON.parse(data.toString());
	    if(json.count % 5 == 0){
		setTimeout(function(){
	    	sx127x.write(new Buffer('Count is ' + json.count), err => {
			console.log('write data', new Buffer('Count is ' + json.count));
			if(err) console.log('send error' , err);
			setRX()
		});
		}, 1000);
	    }
    }catch(e){}
  });

  setRX();
});

function setRX(){
  // enable receive mode
  sx127x.receive(function(err) {
    console.log('receive', err ? err : 'success');
  });
}

process.on('SIGINT', function() {
  // close the device
  sx127x.close(function(err) {
    console.log('close', err ? err : 'success');
    process.exit();
  });
});