Arduino to arduino Serial

Using Arduino Networking, Protocols, and Devices
9

OK. Thanks Power_Broker.
Your info was very helpful. I could establish a connection between my Nano and my Mega using following sketches.

Nano

#include "SerialTransfer.h"
SerialTransfer myTransfer;
void setup()
{
  Serial.begin(1200);
 // Serial1.begin(115200);
  myTransfer.begin(Serial);
}
void loop()
{
  myTransfer.txBuff[0] = 'h';
  myTransfer.txBuff[1] = 'i';
  myTransfer.txBuff[2] = '\n';
  
  myTransfer.sendData(3);
  delay(100);
}

As you see I didn't use serial1 because the Nano only has 1 Serial port (0). It implies that I have to disconnect the serial wires while uploading a sketch. Maybe later I'll try to use SoftwareSerial to avoid this.
I lowered the bitrate to 1200 because (for test purposes), I used just simple (unscreened) wires for Rx, Tx and GND and also because speed is not important for me now.

Mega :

#include "SerialTransfer.h"
SerialTransfer myTransfer;

void setup()
{
  Serial.begin(1200);
  Serial3.begin(1200);
  myTransfer.begin(Serial3);
}
void loop()
{
  if(myTransfer.available())
  {
    Serial.println("New Data");
    for(byte i = 0; i < myTransfer.bytesRead; i++)
      Serial.write(myTransfer.rxBuff[i]);
   // Serial.println();
  }
  else
  {
    Serial.print("ERROR: ");
    Serial.println(myTransfer.status);
  }
  delay(500);
}

The final delay(500) is used to mimic the time that the complete program will need before it gets back to collecting serial data. I used a bitrate of 1200 to print to the Serial Monitor because I've read that using different baud rates on different serials can cause problems.

The result that I see on the Serial monitor (connected to the Mega) is rather weird. It works, but now and then I get error messages... (Same errors when using different baud rates)
Here's what I see on the Serial Monitor of the Mega :

...
New Data
hi
New Data
hi
New Data
hi
New Data
hi
New Data
hi
New Data
hi
ERROR: -1
New Data
hi
ERROR: -1
New Data
hi
New Data
hi
New Data
hi
New Data
hi
New Data
hi
ERROR: 2
ERROR: 2
ERROR: -1
New Data
hi
New Data
hi
New Data
hi
etc ...

Here and there also an ERROR -3 appears ... Maybe the errors appear because the nano is trying to send while the Mega is still reading ? But then why is it always a different error code ?

Anyhow... :slight_smile: I think that (thanks to your info) I am on a good road, but there's still a few "pot holes" ...

So... things BEGIN to work... !!YES!!
Do you have any ideas to smooth out those "pot holes" so that I can go on (and maybe have to ask more questions :slight_smile: )
Again, in advance : I thank you for your "cooperation" :wink:

PS. Nano and Mega are connected to the same PC, but each on their own arduino.exe