problem with the duplex

[ghost]

I have an error when I try to communicate two modules "error: message length does not match length"

Hello, I have two arduino mega 2560 connected at two Ra-02 sx1278 like this:

LORA------------MEGA 3,3--------------3,3 GND-------------GND MOSI------------51 SCK-------------52 MISO-----------50 NSS-------------10 RESET-----------9 DIO0-------------2

and my code is :

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

const int csPin = 7;          // LoRa radio chip select
const int resetPin = 6;       // LoRa radio reset
const int irqPin = 1;         // change for your board; must be a hardware interrupt pin

String outgoing;              // outgoing message

byte msgCount = 0;            // count of outgoing messages
byte localAddress = 0xBA;     // address of this device
byte destination = 0xFF;      // destination to send to
long lastSendTime = 0;        // last send time
int interval = 2501;          // interval between sends

void setup() {
  Serial.begin(9600);                   // initialize serial
  while (!Serial);

  Serial.println("LoRa Duplex");

  // override the default CS, reset, and IRQ pins (optional)
  //LoRa.setPins(csPin, resetPin, irqPin);// set CS, reset, IRQ pin
  LoRa.setPins(10, 9, 2);//NSS, NRESET, and DIO0 pins can be changed by using LoRa.setPins(ss, reset, dio0).

  if (!LoRa.begin(433E6)) {             // initialize ratio at 915 MHz
    Serial.println("LoRa init failed. Check your connections.");
    while (true);                       // if failed, do nothing
  }

  Serial.println("LoRa init succeeded.");
}

void loop() {
  if (millis() - lastSendTime > interval) {
    String message = "HeLoRa world from BA";   // send a message
    sendMessage(message);
    Serial.println("Sending " + message);
    lastSendTime = millis();            // timestamp the message
    interval = random(2000) + 1000;    // 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;          // if there's no packet, 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

  String incoming = "";

  while (LoRa.available()) {
    incoming += (char)LoRa.read();
  }

  if (incomingLength != incoming.length()) {   // check length for error
    Serial.println("error: message length does not match length");
    return;                             // skip rest of function
  }

  // if the recipient isn't this device or broadcast,
  if (recipient != localAddress && recipient != 0xFF) {
    Serial.println("This message is not for me.");
    return;                             // skip rest of function
  }

  // if message is for this device, or broadcast, print details:
  Serial.println("Received from: 0x" + String(sender, HEX));
  Serial.println("Sent to: 0x" + String(recipient, HEX));
  Serial.println("Message ID: " + String(incomingMsgId));
  Serial.println("Message length: " + String(incomingLength));
  Serial.println("Message: " + incoming);
  Serial.println("RSSI: " + String(LoRa.packetRssi()));
  Serial.println("Snr: " + String(LoRa.packetSnr()));
  Serial.println();
}

For the 2nd one, I change the adress for OxBB.

The connetion work one time before write "error: message length does not match length". Somebody can help me ? Thanks

[IoTThinks]

Sometimes, the packet is corrupted and the length may not fit.

CS is actually SS/NSS. Try to change to SS to pin 53. I believe the pins for SPI in Arduino may be fixed.

NSS is pin 53 on the small picture

[ghost]

Thanks for your answer IoTThinks, I have done that :) Well, now It's work for a moment.. and maybe after 5mn It doesn't work anymore.... very strange

[IoTThinks]

Try this example instead. https://github.com/sandeepmistry/arduino-LoRa/blob/master/examples/LoRaDuplexCallback/LoRaDuplexCallback.ino

Check how they use LoRa.onReceive(onReceive) and LoRa.receive() in setup()

Your code below doesn't look right to me. parsePacket() is for single receive mode. and onReceive is for continuous mode.

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

=> "message length does not match length" is understandable now. As parsePacket() will return 0 if no packet is received and onReceive is only called when a packet is received.

[ghost]

I tried your example, it receive one message from the other but after sending his first message, it doesn't receive anything anymore.

If I comment the line of sendMessage in the loop, It receive all the messages from the other...

/*
  LoRa Duplex communication wth callback
  Sends a message every half second, and uses callback
  for new incoming messages. Implements a one-byte addressing scheme,
  with 0xFF as the broadcast address.
  Note: while sending, LoRa radio is not listening for incoming messages.
  Note2: when using the callback method, you can't use any of the Stream
  functions that rely on the timeout, such as readString, parseInt(), etc.
  created 28 April 2017
  by Tom Igoe
*/
#include <SPI.h>              // include libraries
#include <LoRa.h>

#ifdef ARDUINO_SAMD_MKRWAN1300
#error "This example is not compatible with the Arduino MKR WAN 1300 board!"
#endif

const int csPin = 53;          // LoRa radio chip select
const int resetPin = 9;       // LoRa radio reset
const int irqPin = 2;         // change for your board; must be a hardware interrupt pin

String outgoing;              // outgoing message
byte msgCount = 0;            // count of outgoing messages
byte localAddress = 0xBA;     // address of this device
byte destination = 0xFF;      // destination to send to
long lastSendTime = 0;        // last send time
int interval = 2000;          // interval between sends

void setup() {
  Serial.begin(9600);                   // initialize serial
  while (!Serial);

  Serial.println("LoRa Duplex with callback");

  // override the default CS, reset, and IRQ pins (optional)
  LoRa.setPins(csPin, resetPin, irqPin);// set CS, reset, IRQ pin

  if (!LoRa.begin(433E6)) {             // initialize ratio at 915 MHz
    Serial.println("LoRa init failed. Check your connections.");
    while (true);                       // if failed, do nothing
  }

  LoRa.onReceive(onReceive);
  LoRa.receive();
  Serial.println("LoRa init succeeded.");
}

void loop() {
  if (millis() - lastSendTime > interval) {
    String message = "HeLoRa World from ba";   // send a message
    sendMessage(message);
    Serial.println("Sending " + message);
    lastSendTime = millis();            // timestamp the message
    interval = random(10000) + 1000;     // 2-3 seconds
    LoRa.receive();                     // go back into receive mode
  }
}

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){ 
    Serial.println("Receive packet who size == 0");
    return;          // if there's no packet, 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

  String incoming = "";                 // payload of packet

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

  if (incomingLength != incoming.length()) {   // check length for error
    Serial.println("error: message length does not match length");
    return;                             // skip rest of function
  }

  // if the recipient isn't this device or broadcast,
  if (recipient != localAddress && recipient != 0xFF) {
    Serial.println("This message is not for me.");
    return;                             // skip rest of function
  }

  // if message is for this device, or broadcast, print details:
  Serial.println("Received from: 0x" + String(sender, HEX));
  Serial.println("Sent to: 0x" + String(recipient, HEX));
  Serial.println("Message ID: " + String(incomingMsgId));
  Serial.println("Message length: " + String(incomingLength));
  Serial.println("Message: " + incoming);
  Serial.println("RSSI: " + String(LoRa.packetRssi()));
  Serial.println("Snr: " + String(LoRa.packetSnr()));
  Serial.println();
}

If I put this on the both arduino

if (!LoRa.begin(433E6)) {             // initialize ratio at 915 MHz
      Serial.println("LoRa init failed. Check your connections.");
      while (true);                       // if failed, do nothing
    }

    LoRa.onReceive(onReceive);
    LoRa.receive();

just after sendMessage, one arduine receive correctly all but not the other one... strange

[morganrallen]

@TrankilEmil098 if you're using version 0.7.1 please upgrade, we just discovered a bug that could be causing receive to only work once.

[ghost]

I have buy a new module and now that's work ! He was broken. Thanks again guys for you answer!

[IoTThinks]

I made Mega + sx1278 works at https://github.com/sandeepmistry/arduino-LoRa/issues/205#issuecomment-613848638

[cmarcante]

Atention: !LoRa.begin(433E6)) ==> 433 MHz !!!!!!!!!!!!!

[Kongduino]

Attention: LoRa.begin(433E6)) ==> 433 MHz !!!!!!!!!!!!!

Well quite obviously: 443e6 is shorthand for 433000000, ie 433 million. Hence 433 MHz///