help in c communication with arduino

[kapustelis]

hello,
iam begginer in c.. and i need some help. Iam trying to send 0x20 from arduino and get the hex in c program on the pc iam using
RS-232 for Linux and Windows lirary for rs232 communication and when i send 0x20 i get 28ef30 i dont know why.. but i want to get 20 integer type value in c program

the code that i use in c is

n = PollComport(cport_nr, buf, 4095);

    if(n > 0)
    {
      buf[n] = 0;   /* always put a "null" at the end of a string! */


      for(i=0; i < n; i++)
      {
        if(buf[i] < 32)  /* replace unreadable control-codes by dots */
        {
          buf[i] = '.';
        }
      }

[Salem]

And how did you print it?

Additionally, what is the code you used to do the sending?

Because getting something like 28ef30 looks a lot like you sent an address, rather than some data.

[kapustelis]

i found out that you can print it but i want to do somthing like if buf == 20 do that.. this was printed i think using %x

[Salem]

Well that really helps to clear things up for us.

> when i send 0x20 i get 28ef30 i dont know why.. but i want to get 20 integer type value in c program
OK, do you send
- A single space character, which as a single char is decimal 32, or hexadecimal 0x20
- A string of 4 characters "0x20" which you then parse.

What does "20 integer type" mean?

How To Ask Questions The Smart Way

[Click_here]

I'm guessing that you are using the sample program from the website, so I doubt if there is anything wrong with that code. I don't know if this is still a problem with the Arduino, but when serial communication is established, the program on the Arduino used to reset.

What are you doing with the Arduino code?

[edit]
Try running this code from the Arduino
http://arduino.cc/en/Tutorial/ArduinoSoftwareRS232

Have you set up any hardware (MAX232) for the comms? Are you using some sort of breakout board?
[/edit]

[kapustelis]

on arduino there is just 1 line of code Serial.println(0x20, HEX); and it is connected to my usb port..
and yes iam using default code from the page.
the only thing i want to do is to send int and get the int from arduino to c..
thanks alot for replys

[Salem]

> on arduino there is just 1 line of code Serial.println(0x20, HEX); and it is connected to my usb port..
So it has this specification then -> Arduino - Println
So it seems on the face of it that you're expecting "0x20\r\n" down the wire.


You still haven't shown us what you do with 'buf' (see post #1) to print it.


Arduino - Serial

You can use the Arduino environment's built-in serial monitor to communicate with an Arduino board. Click the serial monitor button in the toolbar and select the same baud rate used in the call to begin().

Have you done this?
Does it work?
If it does, the problem is entirely in your 'C' code running on the host.

[kapustelis]

when i use &x to print it i get 28ef30, when i use some other i think &s i get 20.. cant rly say because now i dont have the arduino right now and cant tell you 100%. And iam sure that arduino code is okei because i did alot of arduino projects.. and the code in arduino is just for testing c and thats why its just 1 line

[Salem]

> when i use &x to print it i get 28ef30, when i use some other i think &s i get 20..
Why does it seem like you're printing the ADDRESS of a variable?
You seem to be spraying & though your printf calls (you're mistaking them for scanf calls) like there is no tomorrow - and it's just plain wrong.

int x = 20;
int y = 0x20;
printf("X: Dec=%d, hex=%x, address=%p\n", x, x, &x );
printf("Y: Dec=%d, hex=%x, address=%p\n", y, y, &y );

Next time, SHOW YOUR CODE FFS.