Holding sending data while waiting for data

Using Arduino Programming Questions
1

Hi guys;

I am trying to send data from an Ardiuno ( reading a analog pin ) to a PC and from the PC to the Arduino ( LCD display ).

So far, I did send, received and display the data, but how can I wait for the incomming data without keep sending serial out.

My code just do that at the moment. I send the data like : < 345>< 678>< 234>.... can not hold yet... In the Serial Sending Box : I type : 2.365> and it display on the LCD --> V : 2.365 Volt I leat I got that working, but I want to hold or wait for the incomming data. I did that ---> the comment section but it do : < 567> I type : 2.356 I received : 2 and it send < 789>< 675>

Here my code. Any tips and help will be nice. Programming is not my strong point here. About the values being send, I simply read an open analog pin at the moment.

#include <LiquidCrystal.h>

LiquidCrystal lcd(12,11,10,9,8,7);

const byte anapin = 2;

unsigned int my_value;

unsigned char incom[8];

int j;

boolean state;

void setup()
{
  analogReference(DEFAULT);
  Serial.begin(9600);
  lcd.begin(16,2);
  lcd.clear();
  lcd.print("V : ");
  lcd.setCursor(11,0);
  lcd.print(" Volt");
  for (int i=0;i<8;i++)
  {
     incom[i]=0x20; 
  }  
}

void loop()
{
   my_value = analogRead(anapin);
   Serial.print("<");
   if ( my_value < 999 )
   {
     Serial.print(" "); 
   }  
   Serial.print(my_value, DEC);
   Serial.print(">");
   delay(1000);
 /*  
   state=1;
   if (Serial.available() >0) state=0;
   else state=1;
   while (state==1)
   {
     if (Serial.available() >0) state=0;
     else state=1;
   }
*/   
   j=0;
   while ( Serial.available() > 0 )
   {
       incom[j] = Serial.read();
       if (incom[j]=='>' ) break;
       j++;
       if (j==8) break;
   }
   for (int i=0;i<8;i++)
   {  
     if (incom[i]=='>') break;
     lcd.setCursor((4+i),0);
     lcd.write(incom[i]);
   }
   delay(1000);
   
}
2

Try something like this?

if(Serial.available())
     {
       //Send and display data here, will only run once when data is received
       while(Serial.available()) 
         {
           //process incoming serial data, will do this until serial is out of characters
         }
     }
3

@mweisz481

Thank for the tip. But that code will work for the Processing - PC side. Because it is waiting for data and process it and send data.

In my case, I am sending data first... waiting for a responce / data back and display it. So I have to code in a way that after sending its data, wait for incomming data and display it.

Thank for the effort.

4

Put the data into two arrays, when one is receved, send the other, then update your array pointer.

5

@CrossRoads

Put the data into two arrays, when one is receved, send the other, then update your array pointer.

I think I understand what you are trying to say. That is the PC side... I want to do : send data, wait for incomming data, send the next set, wait for the new set, ....repeat.

I was thinking about the problem, and I was think about the post office. I send a package, I received an acknowledge of sending the package, And I wait for package, and I received an acknowledge of receiving the package. In that context, I can use a state. I init the state, check the state, I send data depending of the state, I updated a new state after being send, I received the data, I updated the state, repeat...

I re-code the program and it it now working. Send data, wait the data, repeat.... well you know the story...

Time to do a Processing code.

Here the new code.

#include <LiquidCrystal.h>

LiquidCrystal lcd(12,11,10,9,8,7);

const byte anapin = 2;

unsigned int my_value;

unsigned char incom[8];

int j;

boolean state;

void setup()
{
  analogReference(DEFAULT);
  Serial.begin(9600);
  lcd.begin(16,2);
  lcd.clear();
  lcd.print("V : ");
  lcd.setCursor(11,0);
  lcd.print(" Volt");
  for (int i=0;i<8;i++)
  {
     incom[i]=0x20; 
  }
  state=0;  
}

void loop()
{
   if (state==0)
   {
     my_value = analogRead(anapin);
     Serial.print("<");
     if ( my_value < 999 )
     {
       Serial.print(" "); 
     }  
     Serial.print(my_value, DEC);
     Serial.print(">");
     state=1;
   }
   delay(1000); 
   j=0;
   while ( Serial.available() )
   {
       incom[j] = Serial.read();
       if (incom[j]=='>' )
       {
         state=0;
         break;
       }  
       j++;
       if (j==8) break;
   }
   for (int i=0;i<8;i++)
   {  
     if (incom[i]=='>') break;
     lcd.setCursor((4+i),0);
     lcd.write(incom[i]);
   }
   delay(1000);
}
6 
 j=0;

while ( Serial.available() )
  {
      incom[j] = Serial.read();
      if (incom[j]=='>' )
      {
        state=0;
        break;
      }  
      j++;
      if (j==8) break;
  }

This is pretty reliant on all 8 bytes coming at once. Why not buffer it up in loop() and act when you get the lot, whenever that is?

(edit) Then you don't need the big delay.

7

@Nick Gammon

Thank for the link and tips. I will look into it and study the code.

I was doing my best to code it. I did test my code, using the serial monitor, and it work "fine" <-- so far... but not to well with the PC side. Processing code.

I was trying to send the data the "wrong" way, maybe right, but it did not work to well in Processing code. I have a "sychronazation" issue. I fix the initial problem, ( keep sending data, no waiting for the data ) using the state/flag methode. I was thinking about CrossRoads idea...so I decide the re-send the data one byte at the time, just I received one byte at a time. So I extract the numbers of an integer like : 1023 - take the BCD out, convert them in ASCII and send it. AT the receiving end, one byte at a time, convert ASCII to integer, and calculate the full integer data. And do the calculation ( find the voltage ) and convert to an integer and set the decimal point to 0.000. After that, extract the BCD numbers and send the data one byte at a time.

During testing, it work but, sometime, it have a few issues with a possible synchronization problem ?

Any second opinion will be nice. I will look into Nick Gammon link's.

Here the Arduino Code :

/*
   Size : 3566 bytes
   
   Serial data out and data in.
   
   Version 2.0
   
   Setup: a LCD 16 X 2 connect the the Arduino
   
   Author setup : Using a DIY LCD Sheild
   
   Analog pin 2 connected to nothing.   
      
   By Serge J Desjardins
   aka techone / tech37
   
   Toronto, Ontario, Canada
   
   Compile and Tested 

*/


#include <LiquidCrystal.h>

LiquidCrystal lcd(12,11,10,9,8,7);

const byte anapin = 2;

unsigned int my_value;

unsigned char incom[8];
int outdata[4];

int j;

boolean state;

void setup()
{
  analogReference(DEFAULT);
  Serial.begin(9600);
  lcd.begin(16,2);
  lcd.clear();
  lcd.print("V : ");
  lcd.setCursor(11,0);
  lcd.print(" Volt");
  for (int i=0;i<8;i++)
  {
     incom[i]=0x20; 
  }
  state=0;  
}

void loop()
{
   if (state==0)
   {
     my_value = analogRead( anapin );
     outdata[0] = my_value / 1000;
     my_value = my_value -( outdata[0] * 1000 );
     outdata[1] = my_value / 100;
     my_value = my_value -( outdata[1] * 100 );
     outdata[2] = my_value / 10;
     outdata[3]= my_value % 10;
     for (int i=0;i<4;i++)
     {
       Serial.write((outdata[i]+48));
     }
     Serial.print(">");
     state=1;
   }
   delay(100); 
   j=0;
   while ( Serial.available() )
   {
       incom[j] = Serial.read();
       if (incom[j]=='>' )
       {
         state=0;
         break;
       }  
       j++;
       if (j==8)
       {
          state=0;  
          break;
       }   
   }
   lcd.setCursor(4,0);
   lcd.print("        ");
   for (int i=0;i<7;i++)
   {  
     if (incom[i]=='>') break;
     lcd.setCursor((4+i),0);
     lcd.write(incom[i]);
   }
   delay(1000);
}

Here the Processing code.

/*
   The PC section. It received data , process it and send data

*/

import processing.serial.*;

Serial myPort;  

int[] inbyte = new int[5];
int[] outbyte = new int[4]; 
int j;

float voltage;

int answer;
int sendinfo;

boolean state;

void setup()
{
   println(Serial.list());
   myPort = new Serial(this, Serial.list()[3], 9600);
  //state=0;
  
}

void draw() 
{
    
  if ( myPort.available() > 0 )
  {
    j=0;    
    while ( myPort.available() >0 )
    {
      inbyte[j] = myPort.read();
      if (inbyte[j]=='>') break;
      j++;
      if (j==4) break;
    }
    
    answer=(inbyte[0]-48)*1000;
    answer=((inbyte[1]-48)*100)+answer;
    answer=((inbyte[3]-48)*10)+answer;
    answer=(inbyte[3]-48)+answer;
    
    voltage= float(answer)*(5.0/1023.0);
    voltage = voltage * 1000.0;
    sendinfo = int(voltage);
       
     outbyte[0] = sendinfo / 1000;
     sendinfo = sendinfo -( outbyte[0] * 1000 );
     outbyte[1] = sendinfo / 100;
     sendinfo = sendinfo -( outbyte[1] * 100 );
     outbyte[2] = sendinfo / 10;
     outbyte[3]=  sendinfo % 10;
    
     myPort.write((outbyte[0]+48));
     myPort.write(".");
     myPort.write((outbyte[1]+48));
     myPort.write((outbyte[2]+48));
     myPort.write((outbyte[3]+48));
     myPort.write(">");
      
  }  
}
8

Updated:

I test the Ardiuno code and the Processing code. It work about 90 % of the time. The raison I was doing it is : Programing exercise and test my opto-coupler linker project. Here the link : http://arduino.cc/forum/index.php/topic,92665.0.html

Good news : The linker work just fine. It send the data properly and display the data <-- kind of :roll_eyes:

Bad news : The voltage reading is a bit off, and it display is like : 2.456 and .456 <-- that shift to the left.

To monitor data : At the Processing side, I can monitor the data in and out. But at the Ardiuno side, I can not monitor the serial data... for now, but with another opto linker, I can monitor the data and it will use an another USB port. I will do it later after I build 2 opto linker.

At the Processing side, I did monitor the data and it is correct data in and out. I have to check the Arduino side.

Thank guys for the tips.