Bit Banging

[sanket joshi]

i want to interface rf-id module using any two pins of 8051(Bit Banging)…

i have written following code..

 

<code>

include<reg51f.h>

#include<string.h>



#define _XTAL_FREQ   11059200

#define Baudrate     9600

#define OneBitDelay  (100000000/Baudrate)



#define port P0

#define lcdport P1  //14,13,12,11 pins of lcd and 1.7,1.6,1.5,1.4 of controller



sbit rs=port^0;        //Register select

sbit rw=port^1;        //Read/Write

sbit en=port^2;        //Enable pin



sbit  UART_RX=P2^0;

sbit  UART_TX=P2^1;



unsigned char d[12]=0,i,l;

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<1100;j++);

}



void lcdcmd(char cmdout)

{

lcdport=cmdout;

rs=0;

rw=0;

en=1;

delay(10);

en=0;

}



void lcddata(char dataout)

{

lcdport=dataout;

rs=1;

rw=0;

en=1;

delay(10);

en=0;

}



void dis_cmd(char cmd_value)

{

char cmd_value1;



cmd_value1 = cmd_value & 0xF0;		//mask lower nibble because PA4-PA7 pins are used.

lcdcmd(cmd_value1);			// send to LCD



cmd_value1 = ((cmd_value<<4) & 0xF0);	//shift 4-bit and mask

lcdcmd(cmd_value1);			// send to LCD

}





void dis_data(char data_value)

{

char data_value1;



data_value1=data_value&0xF0;

lcddata(data_value1);



data_value1=((data_value<<4)&0xF0);

lcddata(data_value1);

}

void __delay_us(unsigned int d)

{

unsigned int i, limit;

limit = d/15;



for(i=0;i<limit;i++);

}





void lcd_init()	// fuction for intialize

{

dis_cmd(0x02);		// to initialize LCD in 4-bit mode.

dis_cmd(0x28);		//to initialize LCD in 2 lines, 5X7 dots and 4bit mode.

dis_cmd(0x0C);

dis_cmd(0x06);

dis_cmd(0x80);

}



void initialize_serialcommunication(void)

{

SCON  = 0x50;

TMOD  = 0x20;

TH1   = 0xFD;

TL1   = 0xFD;

TR1   = 1;

TI    = 1;

}



void init(void)

{

UART_RX = 1;  //set as i/p

UART_TX = 0;  //set as o/p

}



unsigned char receive(void)

{

unsigned char DataValue = 0,i;



//wait for start bit

while(UART_RX==1);



__delay_us(OneBitDelay);

__delay_us(OneBitDelay/2);   // Take sample value in the mid of bit duration



for (  i = 0; i < 8; i++ )

{

if ( UART_RX == 1 )   //if received bit is high

{

DataValue += (1<<i);

}



__delay_us(OneBitDelay);

}



// Check for stop bit

if ( UART_RX == 1 )       //Stop bit should be high

{

__delay_us(OneBitDelay/2);



return DataValue;

}

else                      //some error occurred !

{

__delay_us(OneBitDelay/2);

return 0x000;

}

}



void rfid_data(void)

{

for(i=0;i<12;i++)

{

card_id=receive();



}

}



void main(void)

{

//unsigned char ch;

unsigned char data0[]="CARD ID:";

lcdport=0;

init();

//initialize_serialcommunication();

lcd_init();

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

while(data0!='')

{

dis_data(data0);

delay(20);

i++;

}

while(1)

{

rfid_data();

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

for(l=0;l<12;l++)

{

dis_data(card_id[l]);

delay(20);

}

}

}

but i m getting no character on lcd…

can you please figure out the mistake?

kindly help me…its urgent…

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