RFID tag ID display problem *need help*

[Jasper Nunisa]

Hey guys, Ive been working on displaying the RFID tag ID on a LCD using 8051 microcontroller. I used the simple-to-use RFID module from Positron Technologies and interfaced it to 8051 using Max232. But everytime I scan the tag, it shows some weird characters instead of numbers with checksum value. I connected the module separately by RS232 to the pc using hyperterminal and the tag works just fine but on the LCD it just shows some garbage. Can anybody help me out, please??

 

Here’s the program

//Program to interface RFID with 8051 microcontroller (AT89C51) 

#include<reg51.h>

unsigned int data_out,command=0x80,temp;

sfr lcd_data_pin=0x90; //port 1 

sbit rs=P0^0;        //Register select 

sbit rw=P0^1;        //Read/Write 

sbit en=P0^2;        //Enable pin

unsigned char card_id[12];

 

void delay(unsigned int count)    //Function to provide delay

{

    int i,j;

     for(i=0;i<count;i++)

     for(j=0;j<1275;j++);

}

 

void lcd_command(unsigned char comm)   //Lcd command funtion

{

     lcd_data_pin=comm;

     en=1;

     rs=0;

     rw=0;

     delay(1);

     en=0;

}

 

void lcd_data(unsigned char disp)  //Lcd data function

{

     lcd_data_pin=disp;

     en=1;

     rs=1;

     rw=0;

     delay(1);

     en=0;

}

 

lcd_string(unsigned char *disp)     //Function to send string 

{

     int x;

     for(x=0;disp[x]!=’’;x++)

    {

         lcd_data(disp[x]);

    }

}

void lcd_ini()                  //Function to initialize the LCD

{

    lcd_command(0x38);          

    delay(5);

    lcd_command(0x0F);        

    delay(5);

    lcd_command(0x80);

    delay(5);

} 

 

void recieve()     //Function to recieve data serialy from RS232 

{

    unsigned char k;

     for(k=0;k<12;k++)

     { 

         while(RI==0); 

          card_id[k]=SBUF;

          RI=0;

    }

}

 

void main()

{

    int l;

    TMOD=0x20;            //Enable Timer 1

    TH1=0XFD;

    SCON=0x50;

    TR1=1;                // Triggering Timer 1

    lcd_ini();

    lcd_command(0x81);        //Place cursor to second position of first line 

    lcd_string(“UNIQUE CARD ID:”);

    delay(200);

    while(1)

    {

         recieve();

         lcd_command(0xC1);        //Place cursor to second position of second line

         for(l=0;l<12;l++)

         { 

              lcd_data(card_id[l]);

          }

      }

}

 

[AJISH ALFRED]

Hi Jasper,

 

Try increasing the delay in your code, 

 

void lcd_command(unsigned char comm)   //Lcd command funtion

{

     lcd_data_pin=comm;

     en=1;

     rs=0;

     rw=0;

     delay(1);

     en=0;

}

 

put one more delay after en = 0;

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