rfreader

k, but I am receiving characters in the interrupt handler, how to use those characters in main?

k, but I am receiving characters in the interrupt handler, how to use those characters in main?

Was there something wrong with the solution I have already described?

#include<reg51.h>
#include<string.h>
#include"_LCD_R8C.c"
void serial_int (void) interrupt 4
{
        static unsigned char chr='\0';
        unsigned char str1[]="$0016221826";
        unsigned char str2[]="$0123456789";
        unsigned char c[11],str[11],i,j,str0[11];


        if (RI==1)                      /* it was a receive interrupt */
        {
                RI = 0;                 /* clear the received interrupt flag */
//              TI = 0;                /* signal that there's a new character to send */
                chr = SBUF;             /* read the character into our local buffer */
                c[11]=chr;
                lcd_command(0x10);
                lcd_print_b(chr);
                for(j=0;j<1;j++)
                {
                        for (i = 0; i < 11; i++)
                        {
                                 str[i] = c[i] ;
                        }
                        str[11]='\0';
                 }
                strcpy(str0,str);               /*this step is not necessary*/
                j=strcmp(str0,str1);
                if(j==0)
                {
                        lcd_printxy(1,1,"YES");
                }
                else
                {
                        j=strcmp(str0,str2);
                                if(j==0)
                                {
                                        //open_door();
                                        lcd_printxy(1,1,"YES");
                                }
                                else
                                {
                                        //close_door();
                                        lcd_printxy(2,5,"NO");
                                 }
                 }

        }
}
//      else if(TI == 1)
//              {
//                      TI = 0;
//                      if (chr != '\0')
//                      {
//                              if (chr == '\r') chr = '\n';
//                              SBUF = chr;
//                              chr = '\0';
//                      }
//              }
int main()
{

    lcd_init();
    lcd_clear();
    SCON = 0x50;
    TMOD = 0x20;
    TH1  = 0xFD;
    ET0  = 0;
    TR1  = 1;
//  RI   = 1;
    ES   = 1;
    EA   = 1;
}

here in this method using string comparison the program will be too long to compare 250 no. what to do?
I have blocked TI interrupt because I am not sending any data.
please tell me any mistakes if i have done

My eyes are bleeding.

An ISR should end quickly.
Your ISR should just pick up characters and either place them in a ring buffer for main to pick up and process. Or maybe support the knowledge of the length of keys and that they start with '@' and end with '\n' and fill an array with a single ID and then inform main() when the ID is ready to compare.

Was there anywhere in the answers you got any text that could be seen as us recommending you to move all your code into the ISR?

Your program haven't even a loop anymore - so what do you think happen when main() reaches the final "}"?

c[11]=chr;

You always assign at index 11 - which is outside of an array of 11 elements (0 to 10).
When do you assign the first character to position 0?
When do you assign the second character to position 1?
...

for (i = 0; i < 11; i++)
{
    str[i] = c[i] ;
}
str[11]='\0';

What advantage do you see in (for every received character) copy a character array of 11 characters into a string? Especially since a string in C is also an array of characters, but with a character '\0' as terminator to tell strlen(), strcmp(), strcpy() etc where to stop.

You have nested if (strcmp()) statements - why? Haven't you realized that C can have arrays of arrays? So you can have an array of strings with known keys, and iterate through this array until you find a match or runs out of keys to check?

By the way - such a loop should obviously not be in the interrupt service handler that is intended to pick up a received character or send a character.

Shouldn't you pick up a book about C programming, and spend some time with it?
Right now, you seem to produce mistakes at a very high speed - enough so that your examples could fill a book about different programming mistakes.

You do not get anywhere by random trial and error. Actually, you can get far with that approach. But genetic methods aren't fast. It takes a huge number of generations/iterations to progress. So please stop throwing dices to decide what random changes to make, and get a basic knowledge about C data structures, control statements, data types etc.

I wonder if Keil is using PHP.

The broken display of this thread seems to be caused by a dollar sign in one of my previous posts, that seems to have trigged a replace operation that resulted in an end of the table cell and table row in the middle of the text - so the remaining part of my post is emitted inside a <table> tag but outside any <tr> or <td> tags.

Note to web designers - do care about search/replace with user-supplied data and proper handling of break characters. In this case it is broken html output. In many cases, it is database implementations that allows SQL injection hijacking or killing services.

#include<reg51.h>
#include<string.h>
#include"_LCD_R8C.c"
unsigned char chr;
unsigned char c[11];
void serial_int (void) interrupt 4
{
   if (RI==1)
  {
   RI = 0;
   TI = 0;
   chr = SBUF;
   }
}
int main()
{
unsigned char a[2][11]={"$0016221826","$0123456789"};
    int i,j;
    lcd_init();
    lcd_clear();
    SCON = 0x50;
    TMOD = 0x20;
    TH1  = 0xFD;
    ET0  = 0;
    TR1  = 1;
    RI   = 1;
    ES   = 1;
    EA   = 1;
    for(j=0;j<1;j++)
     {
       for(i=0;i<=10;i++)
        {
          c[i]=chr;
        }
       c[11]='\0';
     }
    for(i=0;i<=1;i++)
   {
       j=strcmp(a,c);
        if(j==0)
         {
             lcd_printxy(1,1,"yes");
         }
        else
          {
            lcd_printxy(1,6,"no");
           }
   }
}

you have told me to use array of strings
the compiler is giving warning in line strcmp(a,c),(BOLD): pointer to different objects.
please help me.

You are continuing your programming by introduction of random changes.
Genetic programming really is not a fast route.

You have arrays of type unsigned char - what did the manual say that strcmp() expects? So why did you make your decision to use unsigned char arrays?

You still don't process received data character-by-character, to get a $ followed by 10 digits before you terminate the string with a '\0' and start comparing with your reference keys.

And you have zero synchronization between your interrupt handler and your main loop.

Your programs are never even close to function, because you are constantly ignoring the information you get about existing errors in the code. Moving the code will not remove the bugs in the code. Or will not automagically include extra code lines to perform the actions that your code do not make.

Why are you even using an interrupt handler for serial communication, if you haven't implemented any buffered solution so that the interrupt handler can operate independently of the main loop? You take the disadvantages with an interrupt-based solution while gaining none of the advantages...

When will you finally consider to spend some time with a good book about C programming?

When will you finally consider to spend some time with a good book about C programming?

newsflash
today pradeepkumar read a C book
today pradeepkumar followed the suggestions in this thread
in other news: today hell froze over

It has happened before, you know.
www.podcastingnews.com/.../hell-freezes-over-350.jpg

ya, for sure I will study c textbook. Will you suggest me any good c book to study..?(online/which is available on internet) I will study for some days, i will correct the mistakes and then i will post my code.

Suggestions here: blog.antronics.co.uk/.../

"online/which is available on internet"

Why not go to a real bookstore, and buy a real book?

Have you considered taking a class?

#include <reg51.h>
#include <string.h>

#include "_LCD_R8C.c"

#define INPUT_LENGTH 12
#define ACCEPTABLE_INPUT_COUNT 2

char input[INPUT_LENGTH];  /* The input from the serial port */
int  input_pos  = 0;       /* Current position to write in the input buffer */
int  input_done = 0;       /* 0 = not done yet, 1 = all input read */

void serial_int (void) interrupt 4
{
    if (!input_done && RI == 1)
    {
        /* Put the input at next position in the input buffer */
        /* Then increase the position */
        input[input_pos++] = SBUF;
//              lcd_command(0xC6);
//              lcd_print_b(SBUF);
//              lcd_command(0xC0);
//              lcd_print_b(input[input_pos]);

                RI = 0;
                SBUF=0;

        /* Check if we have received all input yet */
        if (input_pos >= INPUT_LENGTH)
            input_done = 1;
    }
}

int main()
{
        int i;
    /* Array of data that this programs thinks is acceptable */
    char acceptable_inputs[ACCEPTABLE_INPUT_COUNT][INPUT_LENGTH] = {
        "$0016221826", "$0123456789"
    };

    int acceptable_found = 0;  /* Acceptable input found? */

    /* Initialization */
    lcd_init();
    lcd_clear();
    SCON = 0x50;
    TMOD = 0x20;
    TH1  = 0xFD;
    ET0  = 0;
    TR1  = 1;
    RI   = 1;
    ES   = 1;
    EA   = 1;

    /* Wait until we have received all input */
//    while (!input_done)
//        ;  /* Do nothing */

    /* Check the received input for something we accept */
    for (i = 0; i < ACCEPTABLE_INPUT_COUNT; i++)
    {
        if (memcmp(acceptable_inputs[i], input, INPUT_LENGTH) == 0)
        {
            /* Yes, the data received is acceptable */
            acceptable_found = 1;
            break;  /* Don't have to check any more */
        }
    }

    if (acceptable_found)
        lcd_printxy(1, 1, "Yes");
    else
        lcd_printxy(1, 1, "No");

    return 0;
}

how about this code? please tell me if there is any mistake

I thought you said you were going to take some time to do some study?

I think that would be a far better way to spend your time rather than randomly throwing code around...

Be sure to look-up the use of the volatile qualifier...

There are several errors. But don't you find them when you test your code? You are realizing the existence of a debugger?

1) Your ISR don't do anything in case the input buffer already is filled.
2) You let the ISR pick up 12 characters. Are you sure the 12th character of input[] would match the 12th character of your reference keys?
3) How do you get your ISR to synchronize the input, in case you miss one character or there is one character too much? Consider what happens if you disconnect/reconnect the serial cable while data is transmitting? Wouldn't it be good to consider '$' or '\r' or '\n' as synchronization characters?
4) Why do you send back null characters?

SBUF=0;

Or do you happen to believe that writing 0 to SBUF is clearing the just received character?
5) Do you really think it's safe to ignore the input_done check in main()? How fast can the ISR find 12 characters? How fast can main() start calling memcmp()?
6) Haven't we already discussed the bad idea of having the program run out of main()?
7) Do you happen to think that the 8051 processor works best when it has 16-bit integers to operate on - or you think it needs the "int" data type to fit the values 0 and 1 (or the input position)?

int  input_done = 0;       /* 0 = not done yet, 1 = all input read */

There are several errors. But don't you find them when you test your code? You are realizing the existence of a debugger?

1) Your ISR don't do anything in case the input buffer already is filled.
2) You let the ISR pick up 12 characters. Are you sure the 12th character of input[] would match the 12th character of your reference keys?
3) How do you get your ISR to synchronize the input, in case you miss one character or there is one character too much? Consider what happens if you disconnect/reconnect the serial cable while data is transmitting? Wouldn't it be good to consider the dollar or '\r' or '\n' as synchronization characters?
4) Why do you send back null characters?

SBUF=0;

Or do you happen to believe that writing 0 to SBUF is clearing the just received character?
5) Do you really think it's safe to ignore the input_done check in main()? How fast can the ISR find 12 characters? How fast can main() start calling memcmp()?
6) Haven't we already discussed the bad idea of having the program run out of main()?
7) Do you happen to think that the 8051 processor works best when it has 16-bit integers to operate on - or you think it needs the "int" data type to fit the values 0 and 1 (or the input position)?

int  input_done = 0;       /* 0 = not done yet, 1 = all input read */

#include<reg51.h>
#include "_LCD_R8C.c"

#define INPUT_LENGTH 11
char input[INPUT_LENGTH];  /* The input from the serial port */
int  input_pos  = 0;       /* Current position to write in the input buffer */
char getCharacter (void);        /* read a character from the serial port */

int main()
{
int i;

lcd_init();
lcd_clear();
SCON = 0x50;
TMOD = 0x20;
TH1  = 0xFD;
TR1  = 1;
TI   = 1;
RI   = 1;

while(1==1)
        {

               /* read the next character from the serial port */
                        input[input_pos++] = getCharacter ();

                        for(i=0;i<=input_pos;i++)
                        {
                            lcd_print_b(input[i]);
                        }
        }
}
char getCharacter (void)
{
      char chr[INPUT_LENGTH];           /* variable to hold the new character */
        while (RI != 1) {;}
        chr[input_pos++] = SBUF;
        RI = 0;
        return(chr);
}

first I tried displaying on the hyper terminal. I am getting correct value on the hyper terminal then I tried displaying the received number on the display, but I am getting the wrong value 002100 instead of $0016221826..