LoRa Two Way Communication Failed

Official Hardware Retired Esplora
1

I Have a problem with the concept of LoRa Two Way Communication. I tried to apply this concept in my project. So the project is like this:

when there is an object that passes from point A to point B, the ultrasonic sensor will be triggered and the arduino will send a message from point A to point B. The problem is when point a sends a message to point b, sometimes point b can't send a message back to point a, and vice versa.

The sensor will be attached on left, right, and bellow the pillars.

What i used :

  1. Arduiono Uno R3
  2. LoRa Ra-02
  3. Sensor Ultrasonic HC-SR04

4

here's my messy code.

Transmitter

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

#define TRIGGER1 8
#define TRIGGER2 6
#define TRIGGER3 4

#define ECHO1 7
#define ECHO2 5
#define ECHO3 3

#define LED A0

const int ss = 10;
const int rst = 9;
const int dio0 = 2;

int count = 0;

byte localAddress = 0xBB;     // address of this device
byte destination = 0xFF;      // destination to send to
long lastSendTime = 0;        // last send time
int interval = 50;          // interval between sends

String outgoing;
String LoRaData;

long duration, distance, FIRSTSensor,SECONDSensor,THIRDSensor;


void setup() {
  Serial.begin (115200);
  Serial.println("Starting the system");
  
  Serial.println("LoRa Transmiter"); 

  pinMode(TRIGGER1, OUTPUT);
  pinMode(TRIGGER2, OUTPUT);
  pinMode(TRIGGER3, OUTPUT);
  
  pinMode(ECHO1, INPUT);
  pinMode(ECHO2, INPUT);
  pinMode(ECHO3, INPUT);
  
  pinMode(LED, OUTPUT);

  LoRa.setPins(ss, rst, dio0);
  
  while (!Serial);
  if (!LoRa.begin(433E6)){
    Serial.println("Starting LoRa failed!");
    while(1);
  }
}

void loop() {
  if(millis() - lastSendTime > interval){
    SonarSensor(TRIGGER1, ECHO1);
    FIRSTSensor = distance;

    SonarSensor(TRIGGER2, ECHO2);
    SECONDSensor = distance;

    SonarSensor(TRIGGER3, ECHO3);
    THIRDSensor = distance;
    
    if((FIRSTSensor >=5) & (FIRSTSensor <=8)){
      if((SECONDSensor >=8) & (SECONDSensor <=10)){
        if((THIRDSensor >=5) & (THIRDSensor <=8)){
      
          count = count-1;
          digitalWrite(LED,HIGH); 
          Serial.print("MOBIL TERDETEKSI\n");
          String message = "ONNN";
          sendMessage(message);
          delay(3000);
          //digitalWrite(LED, LOW);
        }
      }
    }
    if(count==0){
      digitalWrite(LED, LOW);
    }
    if(count<=-3){
      //Serial.println("GANTIAN");
      digitalWrite(LED, HIGH);
    }
    //lastSendTime = millis();        // timestamp the message
    //interval = random(50) + 150;    // 2-3 seconds
    //onReceive(LoRa.parsePacket());
  }
     // parse for a packet, and call onReceive with the result:
     onReceive(LoRa.parsePacket());
}

void sendMessage(String outgoing){
  LoRa.beginPacket();                   // start packet
  LoRa.write(destination);              // add destination address
  LoRa.write(localAddress);             // add sender address
  LoRa.print(outgoing);                 // add payload
  //LoRa.endPacket();                     // finish packet and send it
  LoRa.endPacket(true);                 // lora non-blocking mode
}

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

  int recipient = LoRa.read();          // recipient address
  byte sender = LoRa.read();            // sender address

  String incoming = "";                 // payload of packet

  Serial.print("Packet incoming : " + incoming);

  while (LoRa.available()) {            // can't use readString() in callback, so
    incoming += (char)LoRa.read();      // add bytes one by one
  }

  if(incoming == "ONN"){
    //count++;
    digitalWrite(LED, HIGH);
    Serial.println("Message: " + incoming);
    Serial.println("MOBIL TERDTEKSI");
    Serial.println("RSSI: " + String(LoRa.packetRssi()));
    Serial.println("Snr: " + String(LoRa.packetSnr()));
    Serial.println(count = count+1);

  }
}

void SonarSensor(int TRIGGER,int ECHO) {
  
  digitalWrite(TRIGGER, LOW);
  delayMicroseconds(2);
  
  digitalWrite(TRIGGER, HIGH);
  delayMicroseconds(10);
  
  digitalWrite(TRIGGER, LOW);
  duration = pulseIn(ECHO, HIGH);
  distance = (duration/2) / 29.1;

}

Receiver

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

#define TRIGGER1 8
#define TRIGGER2 6
#define TRIGGER3 4

#define ECHO1 7
#define ECHO2 5
#define ECHO3 3

#define LED A0

const int ss = 10;
const int rst = 9;
const int dio0 = 2;

int count = 0;

byte localAddress = 0xBB;     // address of this device
byte destination = 0xFF;      // destination to send to
long lastSendTime = 0;        // last send time
int interval = 50;          // interval between sends

String outgoing;
String LoRaData;

long duration, distance, FIRSTSensor,SECONDSensor,THIRDSensor;


void setup() {
  Serial.begin (115200);
  Serial.println("Starting the system");
  
  Serial.println("LoRa Transmiter"); 

  pinMode(TRIGGER1, OUTPUT);
  pinMode(TRIGGER2, OUTPUT);
  pinMode(TRIGGER3, OUTPUT);
  
  pinMode(ECHO1, INPUT);
  pinMode(ECHO2, INPUT);
  pinMode(ECHO3, INPUT);
  
  pinMode(LED, OUTPUT);

  LoRa.setPins(ss, rst, dio0);
  
  while (!Serial);
  if (!LoRa.begin(433E6)){
    Serial.println("Starting LoRa failed!");
    while(1);
  }
}

void loop() {
  if(millis() - lastSendTime > interval){
    SonarSensor(TRIGGER1, ECHO1);
    FIRSTSensor = distance;

    SonarSensor(TRIGGER2, ECHO2);
    SECONDSensor = distance;

    SonarSensor(TRIGGER3, ECHO3);
    THIRDSensor = distance;

    
    if((FIRSTSensor >=5) & (FIRSTSensor <=8)){
      if((SECONDSensor >=8) & (SECONDSensor <=10)){
        if((THIRDSensor >=5) & (THIRDSensor <=8)){
      
          count = count-1;
          digitalWrite(LED,HIGH); 
          Serial.print("MOBIL TERDETEKSI\n");
          String message = "ONNN";
          sendMessage(message);
          delay(3000);
          //digitalWrite(LED, LOW);
        }
      }
    }
    if(count==0){
      digitalWrite(LED, LOW);
    }
    if(count<=-3){
      //Serial.println("GANTIAN");
      digitalWrite(LED, HIGH);
    }
    //lastSendTime = millis();        // timestamp the message
    //interval = random(50) + 150;    // 2-3 seconds
    //onReceive(LoRa.parsePacket());
  }
     // parse for a packet, and call onReceive with the result:
     onReceive(LoRa.parsePacket());
}

void sendMessage(String outgoing){
  LoRa.beginPacket();                   // start packet
  LoRa.write(destination);              // add destination address
  LoRa.write(localAddress);             // add sender address
  LoRa.print(outgoing);                 // add payload
  //LoRa.endPacket();                     // finish packet and send it
  LoRa.endPacket(true);                 // lora non-blocking mode
}

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

  int recipient = LoRa.read();          // recipient address
  byte sender = LoRa.read();            // sender address

  String incoming = "";                 // payload of packet

  Serial.print("Packet incoming : " + incoming);

  while (LoRa.available()) {            // can't use readString() in callback, so
    incoming += (char)LoRa.read();      // add bytes one by one
  }

  if(incoming == "ONN"){
    //count++;
    digitalWrite(LED, HIGH);
    Serial.println("Message: " + incoming);
    Serial.println("MOBIL TERDTEKSI");
    Serial.println("RSSI: " + String(LoRa.packetRssi()));
    Serial.println("Snr: " + String(LoRa.packetSnr()));
    Serial.println(count = count+1);

  }
}

void SonarSensor(int TRIGGER,int ECHO) {
  
  digitalWrite(TRIGGER, LOW);
  delayMicroseconds(2);
  
  digitalWrite(TRIGGER, HIGH);
  delayMicroseconds(10);
  
  digitalWrite(TRIGGER, LOW);
  duration = pulseIn(ECHO, HIGH);
  distance = (duration/2) / 29.1;

}

The Transmitter and Receiver are bassically the same, but why is it a problem. Is there any way to do LoRa two way communication like the concept i was expecting. Thank you

2

Its probably a problem because after you transmit a packet you then delay for 3 seconds before attempting to recieve a packet;

sendMessage(message);
delay(3000);

So if the packet is transmitted in that 3 seconds, it will be missed.

Also you need to appreciate that the LoRa devices are transceivers only, they are either in transmit or receive mode, so they cannot receive whilst transmitting.

I can point you to a LoRa library that has several worked examples of two way communications with LoRa devices.