if (Serial.available() != 0) ----

Ares111111111 · June 1, 2019, 6:16pm

Greetings to you all,

Could you please help me out with the fallowing code .
The main idea is that i want the loop to keep moving until i send a new input from my keyboard
The code bellow works but after 1 iteration , c loses it’s value and when i print it i does not return any value .
Hope you can help . :o
Thank you!

#include<Servo.h>
#include <SimpleDHT.h>

int motor = 13 ;// 

char c;
char x;


void setup() { 
  Serial.begin(9600);
  pinMode(motor, OUTPUT);
// <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>loop
}
void loop ()
{
  Serial.print( "before  serial ::::    ");

Serial.println( );
Serial.println( c);//
Serial.println( );
Serial.println( );

 :D 
  {
     x = Serial.read();
     c =  x ;
     
   }

    Serial.print( "after serial ::::    ");
     Serial.println( );
    Serial.print(c);
     Serial.println( );

 if(c == 'a'){
  
    digitalWrite(motor, HIGH);
    Serial.print("if statement    ");
   Serial.println( );
    Serial.print(c);
    Serial.println( );
    Serial.println( );
    Serial.println( );
    Serial.print( "----------------------------------------------------------------");
  }
  else if(c == 'b'){
    digitalWrite(motor, LOW);
  }
   delay (2000);

  }

system · June 1, 2019, 6:24pm

:D Uh-oh.

Why not check that there is something to read, before reading it?

Ares111111111 · June 1, 2019, 6:27pm

funny how that got there
here is the code … compiled and shorter

#include<Servo.h>
#include <SimpleDHT.h>

int motor = 13 ;// 

char c;
char x;


void setup() { 
  Serial.begin(9600);
  pinMode(motor, OUTPUT);

}
void loop ()
{
  

if (Serial.available() != 0)
  {
     x = Serial.read();
     c =  x ;
     
   }

 if(c == 'a'){
  
    digitalWrite(motor, HIGH);
    
  }
  else if(c == 'b'){
    digitalWrite(motor, LOW);
  }
   delay (2000);

  }

LarryD · June 1, 2019, 6:41pm

Nothing appears to be wrong.

What are you seeing ‘exactly’ ?

You do not need these 3 lines:
#include<Servo.h>
#include <SimpleDHT.h>
. . .
delay (2000);

system · June 1, 2019, 6:44pm

The code in reply #2 bears very little resemblance to the original code.

funny how that got there

You have a very strange sense of humour.

Ares111111111 · June 1, 2019, 6:58pm

AWOL:
The code in reply #2 bears very little resemblance to the original code.
You have a very strange sense of humour.

regargin the code … i just removed all my prints

larryd:
Nothing appears to be wrong.

What are you seeing ‘exactly’ ?

You do not need these 3 lines:
#include<Servo.h>
#include <SimpleDHT.h>
. . .
delay (2000);

the program is bigger and ai strippet the code a little

the problem i have is that if ( c==‘a’ ) i want it to execute an entire function and keep on going till a new value is inputed from the keyboard .

my program runs good but a the 2nd run of void loop it’s value changes even tho i don’t input anything …

LarryD · June 1, 2019, 7:00pm

the program is bigger and ai strippet the code i'm having problmes

Show us the complete sketch.

system · June 1, 2019, 7:02pm

regargin the code

I have no idea what that means

Ares111111111 · June 1, 2019, 7:28pm

larryd:
Show us the complete sketch.

i’m sorry but i can’t post it all because it will be screened at a later date to check for fraud /cheating .

i will try to make it a little clear .

i want this to run forever , till i enter lets say ‘u’ from keyboard.

if(c == 'a'){
  
    digitalWrite(motor, HIGH);
 

Serial.print(  " print this until c changes value    ");
     
/

Source code :

#include<Servo.h>
#include <SimpleDHT.h>

int motor = 13 ;// 

char c;
char x;


void setup() { 
  Serial.begin(9600);
  pinMode(motor, OUTPUT);

}
void loop ()
{
  

if (Serial.available() != 0)
  {
     x = Serial.read();
     c =  x ;
     
   }

 if(c == 'a'){
  
    digitalWrite(motor, HIGH);
 

Serial.print(  " print this until c changes value    ");
     
    
  }
  else if(c == 'b'){
    digitalWrite(motor, LOW);
  }
   delay (2000);

  }

[/quote]

system · June 1, 2019, 7:36pm

Are you using the serial monitor?
(I'm sorry I can't post all of my answer)

Coding_Badly · June 1, 2019, 7:36pm

Ares111111111:
i'm sorry but i can't post it all because it will be screened at a later date to check for fraud /cheating .

Does that mean you are cheating and are hoping to not get caught?

Robin2 · June 1, 2019, 7:50pm

Ares111111111:
i'm sorry but i can't post it all because it will be screened at a later date to check for fraud /cheating .

So you just want us to help you cheat in a way that won't get you caught ?

...R

Ares111111111 · June 1, 2019, 8:00pm

AWOL:
Are you using the serial monitor?
(I'm sorry I can't post all of my answer)

yes .
if i define global variable c ='h' it will hod value in all stages of the program
but if i input from keyboard lets say 'h' the value will not be retained in c and will not go in that IF for the second time .

In a later stage i will have an App on my Android phone ( receive data from different senors and control parts of a system.

you sir are not helping .
i'm not trying to get something that is already done , i'm stuck at this point and don't have a clue to work around it.
if it make you any happier i will explain , if i post all the code here , and by a change they find it , it will be considered that i got it from here ( even tho i'm the source ) and dismiss my paper

Robin2:
So you just want us to help you cheat in a way that won't get you caught ?

...R

Coding_Badly · June 1, 2019, 8:09pm

Ares111111111:
if i post all the code here , and by a change they find it , it will be considered that i got it from here ( even tho i’m the source ) and dismiss my paper

That would make the people responsible for such decisions unreasonable and incompetent. That seems unlikely.

Was “no outside help” included in your assignment?

Ares111111111 · June 1, 2019, 8:19pm

you can get all the help in the world ... but they check your paper with a computer program ... and if that program finds your paper like ... let's say 60 % similar to other projects ... then that is considered cheating ..

by posting all of my code here i open up to that and after all my work i'm not happy or willing to do it .

now that you know it all ... could someone shine a lite upon my "little" problem ... please ?????

i turn to this forum as a last resort ( i spend half a day writing different codes to make it work with no luck )

system · June 1, 2019, 8:29pm

Just start answering the questions.

Or stop wasting time.

UKHeliBob · June 1, 2019, 9:11pm

What have you got the line ending set to in the Serial monitor ?
Consider what will happen in your program if more than one character is in the input buffer

Geek_Emeritus · June 1, 2019, 9:17pm

I made a few changes: I substituted the built in LED for the motor, and I have it print the value of c. it toggles the LED - we don't all have a servo laying about. a = on, b = off. it runs continuously. I wonder if you are hitting enter after you type a or b?

int LED = 13 ;//

char c;
char x;

void setup() 
{
  Serial.begin(9600);
  pinMode(LED, OUTPUT);
}

void loop ()
{
 

  if (Serial.available() != 0)
    {
     x = Serial.read();
     c =  x ;
    }

  if(c == 'a')
    {
     digitalWrite(LED, HIGH);
    }

  else if(c == 'b')
   {
    digitalWrite(LED, LOW);
   }
  Serial.println(c);
  delay (2000);
}

GolamMostafa · June 2, 2019, 12:38am

Ares111111111:
i want this to run forever , till i enter lets say 'u' from keyboard.
#include<Servo.h>

#include <SimpleDHT.h>

int motor = 13 ;//

char c;
char x;

void setup()
{
Serial.begin(9600);
pinMode(motor, OUTPUT);
}

void loop ()
{
if (Serial.available() != 0)
{
x = Serial.read();
c = x ;
}

if(c == 'a')
{
digitalWrite(motor, HIGH);
Serial.print( " print this until c changes value ");
}
else
if(c == 'b')
{
digitalWrite(motor, LOW);
}
delay (2000);

}

Currently, your above sketch is behaving like these:
1. You enter 'a' from the InputBox (with Line ending tab at No line ending option), the L (built-in LED of UNO) becomes ON and the Serial Monitor keeps showing this message " print this until c changes value " in its OutputBox.

2. You enter 'b' from the InputBox, the L and the message " print this until c changes value " go OFF.

3. You enter 'a' from the InputBox, the process of Step-1 repeats.

4. You enter 'u' from the InputBox, the L remains ON; but, the message gets stopped printing.

Under the above circumstances, what you want exactly? Your statement "i want this to run forever , till i enter lets say 'u' from keyboard" is not clear to me. What is 'this' that will keep running until you enter 'h' from the InputBox/keyboard.

Ares111111111 · June 2, 2019, 6:56am

Thank you all .
I made the changes and everything works like a charm .

Have a good day !