PIC18LF4680 y usb ttl para la comunicación usart / serial

Quiero saber si es posible conectar un dispositivo ttl directamente a mi PIC18LF4680 para comunicación en serie a través de USART. Puedo conectar el dispositivo ttl directamente a mi Arduino Uno sin problemas. Este es mi hardware:

Eldispositivottltiene6pines.(dtr,rxd,txd,vcc(3.3vo5v),cts,gnd).

TengodosfragmentosdecódigodiferentesacontinuaciónquerealizanlacomunicaciónUSART.

Laversiónuno(I)utilizalabibliotecadeperiféricos"usart.h". La versión dos (II) utiliza "TXREG" y "RCREG" para enviar y recibir datos.

Ambas versiones funcionan bien en mi entorno virtual (proteus 8 professional), Pero no en el entorno del mundo real. ¿Me estoy perdiendo un paso? Necesito un especial ¿biblioteca? ¿O no es posible con este chip?

Versión I ---------------------------------------

#include "fuses.h"
#include <p18lf4680.h>
#include <stdio.h>
#include <stdlib.h>
#include <plib/usart.h>


void main(void) {

    TRISB = 0x00;
    OSCCON = 0x76;          // 8mhz (0111 0110)

     LATBbits.LATB4 = 0; 
    LATBbits.LATB1 = 0; 
    LATBbits.LATB0 = 0; 

    unsigned char txt1[] = "Hello World \r\n";
    unsigned char txt2[] = "Enter a number.... \r\n";

    CloseUSART();

    OpenUSART(USART_TX_INT_OFF &
            USART_RX_INT_OFF &
            USART_ASYNCH_MODE &
            USART_EIGHT_BIT &
            USART_CONT_RX &
            USART_BRGH_HIGH &
            USART_ADDEN_OFF ,
            52);


    for(int x=0;x<=20;x++){__delay_ms(50);}

    // write/send intro to PC

    while(BusyUSART());
    putsUSART((char *)txt1);

    for(int x=0;x<20;x++){__delay_ms(50);}

    while(BusyUSART());
    putsUSART((char *)txt2);

    for(int x=0;x<20;x++){__delay_ms(50);}


    while(1){
        sdata = ReadUSART();

        switch(sdata){
            case '1':
                LATBbits.LATB4 = 1; 
                LATBbits.LATB1 = 0; 
                LATBbits.LATB0 = 0;

            break;

            case '2':
                LATBbits.LATB4 = 0;
                LATBbits.LATB1 = 1; 
                LATBbits.LATB0 = 0; 

            break;

            case '3':
                LATBbits.LATB4 = 0; 
                LATBbits.LATB1 = 0; 
                LATBbits.LATB0 = 1; 

            break;


            default:
                LATBbits.LATB4 = 0;
                LATBbits.LATB1 = 0;
                LATBbits.LATB0 = 0; 


            break;
        }
    }

}

-------------------------------------------- --------- Versión II --------------------------------------------

#include "fuses.h"
#include <p18lf4680.h>
#include <stdio.h>
#include <stdlib.h>

#define STRLEN 12

volatile unsigned char t;
volatile unsigned char rcindex;
volatile unsigned char rcbuf[STRLEN];

void USART_init(void){

    TXSTAbits.TXEN = 1;     // enable transmitter
    TXSTAbits.BRGH = 1;     // high baud rate mode
    RCSTAbits.CREN = 1;     // enable continous receiving

    // configure I/O pins
    TRISCbits.TRISC7 = 1;     // RX pin is input
    TRISCbits.TRISC6 = 1;     // TX pin is input (automatically configured)

    SPBRG = 52;            

    PIE1bits.RCIE = 1;      // enable USART receive interrupt
    RCSTAbits.SPEN = 1;     // enable USART


}

void USART_putc(unsigned char c)
{
    while (!TXSTAbits.TRMT); // wait until transmit shift register is empty
    TXREG = c;               // write character to TXREG and start transmission
}

void USART_puts(unsigned char *s)
{
    while (*s)
    {
        USART_putc(*s);     // send character pointed to by s
        s++;                // increase pointer location to the next character
    }
}

void main(void) {

    OSCCON = 0x76;          // 8mhz (0111 0110)

    USART_init();

    USART_puts("Init complete! \n");

    INTCONbits.PEIE = 1;    // enable peripheral interrupts
    INTCONbits.GIE = 1;     // enable interrupts

    while(1)
    {

    }

}

void interrupt ISR(void)
{
    if (PIR1bits.RCIF)  // check if receive interrupt has fired
    {
        t = RCREG;      // read received character to buffer

        // check if received character is not new line character
        // and that maximum string length has not been reached
        if ( (t != '\n') && (rcindex < STRLEN) )
        {
            rcbuf[rcindex] = t; // append received character to string
            rcindex++;          // increment string index
        }
        else
        {
            rcindex = 0;        // reset string index
            USART_puts(rcbuf);  // echo received string
        }

        PIR1bits.RCIF = 0;      // reset receive interrupt flag
    }
}

Toda la ayuda es apreciada. Gracias!