Problem with XC8, RX interrupt [PIC18F4550]

Question

I have a problem with my interrupt and I don't know why. I want to use an interruption each time I receive a data from my RX port. So, I used the interrupt on the port RX of my microcontroller. My problem is, I can detect an interruption but I am locked into the interruption. I'm locked into like a while(1). Any idea?

This is my test code:

//Functions//

void interrupt SerialRxPinInterrupt(void);


int main(int argc, char** argv) 
{
    //Variables//
    unsigned char UARTConfig = 0, baud = 0;


    //Toggle led//
    TRISAbits.RA1=0; //output

    //Configuration internal clock to 8Mhz//
    OSCCONbits.IRCF0 = 1;
    OSCCONbits.IRCF1 = 1;
    OSCCONbits.IRCF2 = 1;

    /*UART PINS*/
    TRISCbits.RC6 = 0; //TX pin set as output
    TRISCbits.RC7 = 1; //RX pin set as input

    //UART Configuration//
    UARTConfig = USART_TX_INT_OFF & USART_RX_INT_ON & USART_ASYNCH_MODE & USART_EIGHT_BIT & USART_BRGH_HIGH ;
    baud=51; //Formula 16(X+1) = Fosc/Baud Rate
    OpenUSART(UARTConfig,baud);

    //Interrupt configuration//
    RCIF = 0; //reset RX pin flag
    RCIP = 0; //Not high priority
    RCIE = 1; //Enable RX interrupt
    PEIE = 1; //Enable pheripheral interrupt (serial port is a pheripheral)
    ei();   //(INTCONbits.GIE = 1)


    while(1)
    {
        LED=1;
    }

    return (EXIT_SUCCESS);
}

    void interrupt SerialRxPinInterrupt(void)
    {
        LED=0;
        //check if the interrupt is caused by RX pin
        if(PIR1bits.RCIF == 1)
        {
            RCIF = 0; // clear rx flag
        }
    }

Answer 1

The UART receive flag is sticky meaning that until the condition that triggered the interrupt is removed, clearing the flag in software will not clear it in hardware. You must read the receive register to clear the flag or before the flag can be cleared.

The following snipet is from the data sheet, interrupt section.

RCIF: EUSART Receive Interrupt Flag bit

1 = The EUSART receive buffer, RCREG, is full (cleared when RCREG is read)

0 = The EUSART receive buffer is empty

Answer 2

You have to clear your buffer .

 void interrupt SerialRxPinInterrupt(void)
{
    LED=0;
    //check if the interrupt is caused by RX pin
    if(PIR1bits.RCIF == 1) && (PIE1bits.RCIE == 1)
    {
        RCIF = 0; // clear rx flag
        data=RCREG;
        CommReceiveFin:      
    }  
}