PIC18 firmware for RGB LED driver

rgb-led-fw.c

#define ST_CHAR 0xFE
#define ESC_CHAR 0xFD
#define MSG_LEN 6

unsigned char rxCounter = 0, escaped = 0, in_msg = 0, rxBuffer[MSG_LEN];

void parseSerialMsg(void) {
    static unsigned char byte, status;

    if (DataRdyUSART()) {
        byte = getcUSART();

        if ( (!in_msg) && (byte != ST_CHAR) ) {
            status = 'n';
            in_msg = 0;

        } else if ( byte == ST_CHAR ) {

            if (escaped) {
                status = 'd';

                rxBuffer[rxCounter++] = byte;
                escaped = 0;
            } else {
                status = 's';

                rxCounter = 0;
                in_msg = 1;
                escaped = 0;
            }
        } else if ( byte == ESC_CHAR ) {
            if (escaped) {
                status = 'd';

                rxBuffer[rxCounter++] = byte;
                escaped = 0;
            } else {
                status = 'e';

                escaped = 1;
            }

        } else {
            status = 'd';

            rxBuffer[rxCounter++] = byte;
            escaped = 0;

        }

        if ( rxCounter == MSG_LEN ) {
            status = 'k';

            rxCounter = 0;
            escaped = 0;
            in_msg = 0;
            paintLED(rxBuffer);
        }

        while(BusyUSART());
        putcUSART(status);
    }
}

void paintLED(char* colors) {
    static unsigned char i,j;

    // Set colors of LED0
    for (i=0; i<6; i++) {
        ledDriverMsg[27-i] = colors[i];
    }

    // Stream data
    PORTBbits.RB1 = 1;
    for(i=0; i<28; i++) {
        for(j=8; j>0; j--){
            PORTBbits.RB1 = 0;
            PORTBbits.RB0 = ( ledDriverMsg[i]>>(j-1) ) & 0x01;
            PORTBbits.RB1 = 1;
        }
    }
    PORTBbits.RB0 = 0;
    PORTBbits.RB1 = 0;
}

void highISR(void);

#pragma code HIGH_INTERRUPT_VECTOR = 0x8
/* High-priority service */
void high_ISR(void) {
    _asm
        goto highISR
    _endasm
}
#pragma code

#pragma interrupt highISR
/* High-priority service */
void highISR(void) {

    if(PIR1bits.RCIF) {
        PIE1bits.RCIE = 0;

        // Real function to execute
        parseSerialMsg();

        // Clear Interrupt Flag
        PIR1bits.RCIF = 0;
        PIE1bits.RCIE = 1;
    }
}