RCREG data, PIC 18f4550 not displaying value - pic

Question

I interfaced RFID with PIC 18f4550, I tried displaying values of RCREG on LCD, but only got a box displayed. What could be the problem?
I am using MPLAB X with the XC8 compiler
// Program to interface RFID module using EUSART in PIC18F2550
#include <p18f4550.h>
#include <stdio.h>
/* _CPUDIV_OSC1_PLL2_1L, // Divide clock by 2
_FOSC_HS_1H, // Select High Speed (HS) oscillator
_WDT_OFF_2H, // Watchdog Timer off
MCLRE_ON_3H // Master Clear on
*/
// CONFIG1L
#pragma config PLLDIV = 1 // PLL Prescaler Selection bits (No prescale (4 MHz oscillator input drives PLL directly))
#pragma config CPUDIV = OSC1_PLL2// System Clock Postscaler Selection bits ([Primary Oscillator Src: /1][96 MHz PLL Src: /2])
#pragma config USBDIV = 1 // USB Clock Selection bit (used in Full-Speed USB mode only; UCFG:FSEN = 1) (USB clock source comes directly from the primary oscillator block with no postscale)
// CONFIG1H
#pragma config FOSC = INTOSC_HS // Oscillator Selection bits (Internal oscillator, HS oscillator used by USB (INTHS))
#pragma config FCMEN = OFF // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled)
#pragma config IESO = OFF // Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled)
// CONFIG2L
#pragma config PWRT = OFF // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOR = ON // Brown-out Reset Enable bits (Brown-out Reset enabled in hardware only (SBOREN is disabled))
#pragma config BORV = 3 // Brown-out Reset Voltage bits (Minimum setting)
#pragma config VREGEN = OFF // USB Voltage Regulator Enable bit (USB voltage regulator disabled)
// CONFIG2H
#pragma config WDT = ON // Watchdog Timer Enable bit (WDT enabled)
#pragma config WDTPS = 32768 // Watchdog Timer Postscale Select bits (1:32768)
// CONFIG3H
//#pragma config CCP2MX = ON // CCP2 MUX bit (CCP2 input/output is multiplexed with RC1)
#pragma config PBADEN = ON // PORTB A/D Enable bit (PORTB<4:0> pins are configured as analog input channels on Reset)
#pragma config LPT1OSC = OFF // Low-Power Timer 1 Oscillator Enable bit (Timer1 configured for higher power operation)
#pragma config MCLRE = ON // MCLR Pin Enable bit (MCLR pin enabled; RE3 input pin disabled)
// CONFIG4L
#pragma config STVREN = ON // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config LVP = ON // Single-Supply ICSP Enable bit (Single-Supply ICSP enabled)
#pragma config ICPRT = OFF // Dedicated In-Circuit Debug/Programming Port (ICPORT) Enable bit (ICPORT disabled)
// #pragma config XINST = OFF // Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode))
// CONFIG5L
#pragma config CP0 = OFF // Code Protection bit (Block 0 (000800-001FFFh) is not code-protected)
#pragma config CP1 = OFF // Code Protection bit (Block 1 (002000-003FFFh) is not code-protected)
//#pragma config CP2 = OFF // Code Protection bit (Block 2 (004000-005FFFh) is not code-protected)
//#pragma config CP3 = OFF // Code Protection bit (Block 3 (006000-007FFFh) is not code-protected)
// CONFIG5H
#pragma config CPB = OFF // Boot Block Code Protection bit (Boot block (000000-0007FFh) is not code-protected)
//#pragma config CPD = OFF // Data EEPROM Code Protection bit (Data EEPROM is not code-protected)
// CONFIG6L
#pragma config WRT0 = OFF // Write Protection bit (Block 0 (000800-001FFFh) is not write-protected)
#pragma config WRT1 = OFF // Write Protection bit (Block 1 (002000-003FFFh) is not write-protected)
//#pragma config WRT2 = OFF // Write Protection bit (Block 2 (004000-005FFFh) is not write-protected)
//#pragma config WRT3 = OFF // Write Protection bit (Block 3 (006000-007FFFh) is not write-protected)
// CONFIG6H
#pragma config WRTC = OFF // Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) are not write-protected)
#pragma config WRTB = OFF // Boot Block Write Protection bit (Boot block (000000-0007FFh) is not write-protected)
//#pragma config WRTD = OFF // Data EEPROM Write Protection bit (Data EEPROM is not write-protected)
// CONFIG7L
#pragma config EBTR0 = OFF // Table Read Protection bit (Block 0 (000800-001FFFh) is not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF // Table Read Protection bit (Block 1 (002000-003FFFh) is not protected from table reads executed in other blocks)
//#pragma config EBTR2 = OFF // Table Read Protection bit (Block 2 (004000-005FFFh) is not protected from table reads executed in other blocks)
//#pragma config EBTR3 = OFF // Table Read Protection bit (Block 3 (006000-007FFFh) is not protected from table reads executed in other blocks)
// CONFIG7H
#pragma config EBTRB = OFF
// Program to interface RFID module using EUSART in PIC18F4550
// Configuration bits
/* _CPUDIV_OSC1_PLL2_1L, // Divide clock by 2
_FOSC_HS_1H, // Select High Speed (HS) oscillator
_WDT_OFF_2H, // Watchdog Timer off
MCLRE_ON_3H // Master Clear on
*/
#define FREQ 20000000
#define baud 9600
#define spbrg_value 19
#define rs LATAbits.LATA0
#define rw LATAbits.LATA1
#define en LATAbits.LATA2
#define lcdport LATB
unsigned char rx_data();
void lcd_ini();
void lcdcmd(unsigned char);
void lcddata(unsigned char);
unsigned char data[]="Unique ID No.";
unsigned char card_id[12];
unsigned int i=0,j=0,pos;
void Delay_ms(int t)
{
int i;
int j;
for (i=0;i<t;i++)
for(j=0;j<100;j++);
}
void main()
{
TRISB=0; // Set Port B as output port
LATB=0;
TRISA=0;
LATA=0;
SPBRG=spbrg_value; // Fill SPBRG register to set the baud rate
RCSTAbits.SPEN=1; // To activate serial port (Tx and Rx pins)
RCSTAbits.CREN=1; // To enable continuous reception
PIE1bits.RCIE=1; // To enable the Reception (Rx) Interrupt
INTCONbits.GIE=1;
INTCONbits.PEIE=1;
lcd_ini(); // LCD initialization
while(data[i]!='\0')
{
//lcddata(data[i]); // To send characters one by one from 'data' array
i++;
}
while(1)
{
i=0;
while(PIR1bits.RCIF ==0);
}
}
void interrupt ISR()
{
i=0;
unsigned char c = 'P';
lcddata(c);
while(i<12)
{
card_id[i]=RCREG;
lcddata(card_id[i]);
i++;
}
card_id[11]='\0';
/*while(i<12)
{
char cc=card_id[i];
lcddata(cc);
i++;// Print the 12 byte received
}}
while(data[i]!='\0'){
lcddata(data[i]);
i++;
}*/
}
void lcd_ini()
{
lcdcmd(0x38); // Configure the LCD in 8-bit mode, 2 line and 5x7 font
lcdcmd(0x0C); // Display On and Cursor Off
lcdcmd(0x01); // Clear display screen
lcdcmd(0x06); // Increment cursor
lcdcmd(0x80); // Set cursor position to 1st line, 1st column
}
void lcdcmd(unsigned char cmdout)
{
lcdport=cmdout; //Send command to lcdport=PORTB
rs=0;
rw=0;
en=1;
Delay_ms(10);
en=0;
}
void lcddata(unsigned char dataout)
{
lcdport=dataout; //Send data to lcdport=PORTB
rs=1;
rw=0;
en=1;
Delay_ms(10);
en=0;
}
I keep getting an error saying illegal conversion of pointer to string on the line where i assign card_id[i] the value of RCREG and it seems that RCREG is returning the address

Answer 1

The watchdog timer is enabled #pragma config WDT = ON but never cleared. Periodically call ClrWdt(); or disable it, otherwise the program will reset every time the watchdog timer expires.
Not causing a problem but worth mentioning, with XC8 Microchip recommends using #include <xc.h> which will make including the processor specific header unnecessary.
The character that is in RCREG is being moved into all 12 elements of card_id, was that really intended?
The UART will assert an interrupt and set RCIF each time a character is received. Reading RCREG clears the flag. It's generally not a good idea to do tasks (especially ones with delays) while servicing the interrupt because incoming characters can be missed. Consider establishing a circular queue and doing something like this:
void interrupt ISR()
{
while(PIR1bits.RC1IF){
queue1[q1tail] = RCREG1;
if(++q1tail >= Q_SIZE)
q1tail = 0;
}
}
Then in the main forever loop check the queue. When something comes in (q1tail != q1head) process it as necessary and pop it off the queue (increment q1head).
It's also a good idea to check for overrun and framing errors. It can be done when checking the queue pointers:
if (RCSTA1bits.OERR || RCSTA1bits.FERR)
{
RCSTA1bits.CREN = 0;
Nop();
Nop();
RCSTA1bits.CREN = 1;
}