Trouble with Serial Communication between Two Arduino Megas

Projects Programming
1

I'm attempting to transfer sensor data from one Mega to another Mega that will be used to interpret it. My master code is:

#include <SoftwareSerial.h>
#include "Adafruit_ADS1X15.h"
SoftwareSerial mySerial(17, 16); //Rx,Tx
float diametermm = 0;
float diameterin = 0;
float voltage = 0;
char text[20];
char charVal[6];
Adafruit_ADS1115 ads1115;
void setup() {

  pinMode(17, INPUT);
  pinMode(16, OUTPUT);
  mySerial.begin(9600);
  Serial.begin(9600);
  ads1115.begin();

}

void loop() {
  int16_t adc0;
  adc0 = ads1115.readADC_SingleEnded(0);
  voltage = (adc0 * .1875) / 1000;
  //strcat(text, "DIA is: ");
  diametermm = (voltage * 7.8587) - .5242;
  diameterin = diametermm * 0.0394;
  //Serial.println(diameterin, 4);
  //dtostrf(diameterin,5,1,charVal);
  //strcat(text, charVal);
  /// text[16] = 0;
  //strcat(text,"in");
  //Serial.println(text);
  Serial.println(diameterin,4);
}

And my Slave code is slave code is:

#include <SoftwareSerial.h>
SoftwareSerial mySerial(17, 16);

void setup() {
   pinMode(17,INPUT);
   pinMode(16,OUTPUT);

  Serial.begin(9600);

}

void loop() {
  if (mySerial.available()){
    int diameter = Serial.read();
    Serial.println(diameter);
  }
}
I'm trying to figure out how to collect the data on the second mega if anyone can help me.
2

Bring the following changes in your sketches and then re-run them.

Master Sketch:

//#include <SoftwareSerial.h>
#include "Adafruit_ADS1X15.h"
//SoftwareSerial mySerial(17, 16); //Rx,Tx
float diametermm = 0;
float diameterin = 0;
float voltage = 0;
char text[20];
char charVal[6];
Adafruit_ADS1115 ads1115;
void setup() {

  //pinMode(17, INPUT);
 // pinMode(16, OUTPUT);
  //my
  Serial2.begin(9600);
  Serial.begin(9600);
  ads1115.begin();

}

void loop() {
  int16_t adc0;
  adc0 = ads1115.readADC_SingleEnded(0);
  voltage = (adc0 * .1875) / 1000;
  //strcat(text, "DIA is: ");
  diametermm = (voltage * 7.8587) - .5242;
  diameterin = diametermm * 0.0394;
  //Serial.println(diameterin, 4);
  //dtostrf(diameterin,5,1,charVal);
  //strcat(text, charVal);
  /// text[16] = 0;
  //strcat(text,"in");
  //Serial.println(text);
  Serial.println(diameterin, 4);
  Serial2.print(diameterin, 4);
  Serial2.print('\n');    //Newline character as end mark
  delay(1000);  //1-sec test interval
}

Slave Sketch:

//#include <SoftwareSerial.h>
//SoftwareSerial mySerial(17, 16);
float diameterin;
char myData[5] = {0};

void setup() 
{
   //pinMode(17,INPUT);
  // pinMode(16,OUTPUT);

  Serial.begin(9600); 
  Serial2.begin(9600);
}

void loop() 
{
  if (Serial2.available() >0 )
  {
      byte m = Serial2.readBytesUntil('\n', myData, 10);
      myData[m] = '\0';  //insert null-character
      diameterin = atof(myData);
      Serial.println(diameterin);
      memset(myData, 0, 10) //array clear
  }
}
1 Like
3

Thank you very much it is working. I totally forgot about the various numbered serial ports on the mega.

1 Like
4

F.Y.I.: Don't use pinMode() on the pins that SoftwareSerial is using.

F.Y.I: Same here, plus you forgot mySerial.begin(9600); on the slave side.

5

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