Displaying multiple serial data items via processing

jimbojohn

Hi everyone,

I have an Arduino Mega which is sending some predefined data to an Arduino Uno. Namely "Air temperature", "Oil temperature" and "Battery voltage". Consider also that I have checked the incoming serial data into the Uno and confirmed that the correct data is received. Now my problem is that I can not get these data displayed properly using processing. I am trying to display each of the three data items in a separate line. "Air temperature" should read a value of "2266". "Oil temperature" should read a value of "2159" and "Battery voltage" should read a value "531". So I am looking for an output on the screen that looks something like:

Air temp is: 2266 Oil temp is: 2159 Battey voltage is: 531

I would appreciate it if you have a look at my code and let me know where I am going wrong.

Here's my Code on Arduino IDE which is being compiled on Uno:

unsigned char buff[14];
void setup()  
{
  // Open serial communications and wait for port to open:
  Serial.begin(9600); //talk to laptop
}

void loop() // run over and over
{  
  if (Serial.available() == 14) // I'm sending 14 bytes and want to check that some bytes are read, before filling the buff

  {
    if (Serial.read() == 0x82)
    {
      if (Serial.read() == 0x81)
      {
        if (Serial.read() == 0x80)
        {
          buff[0] = 0x82;
          buff[1] = 0x81;
          buff[2] = 0x80;
          for (int i = 3; i<14; i++)
          {
            buff[i] = Serial.read();
          }

          /*for(int k = 0; k<14;k++)  // supposed to empty the buffer or reset it
           {
           Serial.read();
           }*/
        }
      }
    }
  } 
  if (buff[0] == 0x82 && buff[1] == 0x81 && buff[2] == 0x80)
  {

    int c = ((buff[4] << 8) + buff[5])/10;

    Serial.print("Air temp is: ");
    Serial.println(c);
    Serial.print('F');

    int d = ((buff[6] << 8) + buff[7])/10;
    Serial.print("Oil temp is: ");
    Serial.println(d);
    Serial.print('J');

    int e = ((buff[8] << 8) + buff[9])/10;
    Serial.print("Battey voltage is: ");
    Serial.println(e);
    Serial.print('N');
    //Serial.println(freeRam());
  }
}

Here's the code that I run on processing for Uno:

import processing.serial.*;
Serial myPort;
String Air_temp="";
String Oil_temp="";
String Battey_voltage="";
PFont font;
int lf = 10;


void setup() {
  size(500, 500);
  myPort = new Serial(this, "COM24", 9600);
  myPort.bufferUntil('N');
  font = createFont(PFont.list()[2], 32);
  textFont(font);
}

void draw() {
  //The serialEvent controls the display
}  

void serialEvent (Serial myPort) {

  Air_temp = myPort.readStringUntil('F');
  //Oil_temp = myPort.readStringUntil('J');
  //Battey_voltage = myPort.readStringUntil('N');
  /*  if(Air_temp != null){
   Air_temp=trim(Air_temp);
   }*/

  text(Air_temp, 1, 60);
  //text(Oil_temp,width/10,height/20);
  // text(Battey_voltage,10,40);
}


void writeText(String textToWrite) {

  background(255);
  fill(0);
  text(textToWrite, width/20, height/2);
}

Here's the result that I get from processing:

arthurrep

Serial.print("Air temp is: ");   
Serial.println(c);      println comes too early
Serial.print('F');

marcometro

I am curious why you would want to send the presentation layer stuff ("Air temp is: ") through the serial port. I would think it would be more efficient to just pass the data and allow the Processing sketch to label it. I have seen some serialEvent() code that may do this better for you:

void serialEvent(Serial g_serial_port) {
/*Listens on the serial port and assigns values to global 
  variables. d_first_char is used for deciding what kind of 
  input is being rec'd.
  */
  //-- constructor --
    String d_sensor_str = new String(g_serial_port.readBytesUntil('\n'));
  //-- process sensor input to global vars --
    g_sensor_str = trim(d_sensor_str); // dump the carriage return
    char d_first_char = g_sensor_str.charAt(0);
  //
  //master if
  //
  if (d_first_char == 'c') {
     g_sensor_counter    = int(g_sensor_str.substring(1));
  } else if (d_first_char == 'p') {
     g_sensor_momnt_int  = int(g_sensor_str.substring(1));
  } else if (d_first_char == 't') {
     g_sensor_thermo_int = int(g_sensor_str.substring(1));
  }//else if
}//serialEvent

You can use bufferUntil() to detect a character like newline to fire off the serialEvent. In the code above, vars with "g_" in the name are the global vars to be set.