Arduino UNO LoRa SX1278 not sending/receiving data correctly - c++

Question

When I upload the code to try 2-way communication of LoRa Sx1278 with Arduino UNO it fails to work. I am using 2 modules with the same code. This is the output I receive:
23:09:27.186 -> Received packet: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^' with RSSI -70
23:09:28.207 -> Sending message
I understand the module receives a message but fails to read it, and the second LoRa module with the receiver code fails.
Here is my code:
#include <Wire.h>
#include <SPI.h>
#include <LoRa.h>
String outgoing;
byte msgCount = 0; // count of outgoing messages
byte localAddress = 0xBB; // address of this device
byte destination = 0xFF; // destination to send to
long lastSendTime = 0; // last send time
int interval = 300; // interval between sends
void setup() {
Serial.begin(115200);
while (!Serial);
Serial.println("LoRa Two-Way Communication");
if (!LoRa.begin(433E6)) {
Serial.println("Starting LoRa failed!");
delay(100);
while (1);
}
}
void loop() {
if (millis() - lastSendTime > interval) {
String message = "data from sensors";
Serial.println("Sending message");
sendMessage(message);
// Serial.println("Sending " + message);
lastSendTime = millis(); // timestamp the message
interval = random(50) + 300; // 2-3 seconds
}
// 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.write(msgCount); // add message ID
LoRa.write(outgoing.length()); // add payload length
LoRa.print(outgoing); // add payload
LoRa.endPacket(); // finish packet and send it
msgCount++; // increment message ID
}
void onReceive(int packetSize) {
if (packetSize == 0) return;
// read packet header bytes:
int recipient = LoRa.read(); // recipient address
byte sender = LoRa.read(); // sender address
byte incomingMsgId = LoRa.read(); // incoming msg ID
byte incomingLength = LoRa.read(); // incoming msg length
// received a packet
Serial.print("Received packet: ");
String LoRaData = LoRa.readString();
Serial.print(LoRaData);
// read packet
while (LoRa.available()) {
Serial.print((char)LoRa.read());
}
// print RSSI of packet
Serial.print("' with RSSI ");
Serial.println(LoRa.packetRssi());
delay(1000);
}
I got the code from a tutorial and changed it so it is used to test the module for 2-way communication. Earlier, I tried an example from the library "LoRa Sender" and "LoRa Receiver" and it works flawlessly, so this isn't a hardware issue as far as I am concerned.

Answer 1

There are a few things that are not quite right in the code, but the main one is this: interval = random(50) + 300; // 2-3 seconds That's nowhere near 2 seconds. interval is in milliseconds, so a maximum of 50+300 will give you 0.35 seconds. Which means that both devices are transmitting NON-STOP, and can't hear each other. Try something like 2000 + random(1000)... Although there are better ways to get a random than using random. But anyway.
Also, stay off 433e6, it's a busy frequency, and if there are people nearby with a car remote control, you'll receive a lot of stuff not from you.